Keywords: Agriculture
Prairie grower groups fund research projects targeting canola diseases
35513Ian MacKay, Oyen Echo, 2026-03-17 08:56:22.
Three projects intended to deal with the canola disease verticillium stripe stand out among 11 research programs that a prairie growers consortium is funding this year. Leaders of the canola agronomic research program have chosen projects that they feel are “key to advancing canola productivity and mitigating production threats,” a statement said. The organization includes SaskOilseeds and similar Manitoba and Alberta grower groups, which together are spending over $2.4 million. Results Driven Agriculture Research in Alberta is supplying over $1 million and the Western Grains Research Foundation will chip in $495,000 to bring the total planned expenditure to over $4 million. “The genetic improvement and disease risks facing canola production need to be researched to find solutions,” said Laura Reiter of Radisson, who chairs the Western Grains Research Foundation. “As capacity among public research institutions decreases, grower-led investment isn't just an option anymore, it’s critical to the longevity of our industry,” said Cheryl Westman of Vermilion, who chairs Alberta Canola’s research program. A University of Calgary scientist heads a project titled “Discovering the verticillium longisporum genetic determinants of virulence,” a University of Manitoba scientist aims to test “biocontrol-based strategies” to deal with verticillium stripe in canola and another researcher from that university will use “genetic and molecular approaches” to increase canola’s resistance to verticillium stripe.
A distorter–restorer system drives quantitative reproductive isolation in rice
35461Zhang, Y., Yang, Y., Shi, C. et al., Nature Plants, 2026-02-24 10:08:29.
Hybrid sterility and segregation distortion are the major forms of postzygotic reproductive isolation in rice, yet the molecular basis of their quantitative variation remains unclear. Here we identify S44, a natural distorter–restorer system in Oryza longistaminata/Asian cultivated rice hybrids, comprising four tightly linked elements—Reproductive Isolation Distorter (RID), Reproductive Isolation Restorer (RIR), Reproductive Isolation Activator (RIA) and Reproductive Isolation Suppressor (RIS)—which collectively regulate hybrid male sterility and segregation distortion. The distorter RID triggers the elimination of O. sativa cultivar RD23 pollen, whereas the restorer RIR selectively safeguards O. longistaminata gametes, thereby preferentially transmitting its allele into the progeny. RIS and RIA fine-tune segregation distortion. We further demonstrate that the allelic conflicts at the S44 locus drive quantitative reproductive isolation between O. longistaminata and other rice lineages, and CRISPR-engineered RID knockout can universally overcome S44-mediated reproductive barriers in the AA genome, enabling revolutionary cross-species breeding. This distorter–restorer system provides a unique genetic module for deciphering speciation mechanisms and advancing crop breeding strategies.
Biocontrol practitioners’ perspectives on emerging genetic-based technologies for weed management
35412Rafter, M.A., Kumaran, N., Brookes, D.R. et al., BioControl, 2026-01-31 16:43:25.
Weed biocontrol researchers have been at the forefront of developing management solutions for invasive weeds for over 100 years and have a unique perspective to offer on the emerging field of genetic-based technologies such as gene drive and RNAi. As part of the XVI International Symposium on Biological Control of Weeds in May 2023 we conducted a focus group discussion workshop to explore biocontrol practitioners’ perspectives related to: (1) Genetic-based control technologies, and the factors influencing support (or not) for their application to weed management, especially weed biocontrol, (2) perceived opportunities to apply genetic-based control tools to enhance or complement weed biocontrol, focusing on whether/how genetic tools can be applied to fundamentally change the practice of weed biocontrol, and (3) genetic-based control in weed management and how it can operate within the Access and Benefit Sharing regulatory landscape. We analyse the perspectives of biocontrol scientists from the workshop and discuss the prospects and challenges of integrating novel genetic-based control tools with weed biocontrol.
Identification and evaluation of two testis-specific serine/threonine kinase genes from multi-tissue transcriptomes as potential genetic targets of sterile insect technique in Zeugodacus tau
35439Weijun Li, Cuikang Xu, Hongshi Chen, et al., Pest Management Science, 2026-01-15 18:32:40.
Zeugodacus tau (Walker) is a notorious agricultural pest causing significant economic losses in vegetable production for many years. Sterile insect technique (SIT) has emerged as an environmentally sustainable pest management strategy. However, discovery of molecular targets applicable for SIT implementation in Z. tau still constitutes a significant research gap. We conducted comparative transcriptome analysis of four male tissues (midgut, Malpighian tubules, fat body, and testis), identifying 9653 differentially expressed genes (DEGs) with predominant testis enrichment. Bioinformatics screening revealed 3020 testis-specific highly expressed genes showing significant functional enrichment in cytoplasmic translation, cytosolic ribosome assembly, and oxidoreductase activity. Quantitative real-time PCR (qRT-PCR) assay was utilized to confirm 10 testis-specific genes, including two serine/threonine kinases (ZtTSSK1 and ZtTSSK3) which were significantly enriched in spermatid development. Fluorescence in situ hybridization (FISH) localized the two genes specifically to the transformation zone of Z. tau testis. Functional characterization via RNAi bioassay demonstrated that suppression of ZtTSSKs expression levels reduced spermatozoa number and impaired male fertility. These results establish ZtTSSKs as crucial regulators of male fertility in Z. tau and identify them as potential molecular targets for developing SIT-based interventions against this economically significant pest.
Sterile insect technique reduces cabbage maggot (Diptera: Anthomyiidae) infestation in root crucifers in Canada
35337Anne-Marie Fortier, Allen Bush-Beaupré, Jade Savage, et al., Journal of Economic Entomology, 118:2710–2717. 2026-01-07 11:20:58.
The cabbage maggot (Delia radicum (L.)) is a major pest of brassica vegetables in Canada that has traditionally been managed with soil-applied insecticides. However, recent regulatory restrictions on key products such as chlorpyrifos have created a pressing need for alternative solutions. This study evaluates the sterile insect technique (SIT) as a control method for the cabbage maggot in root crucifers. Large-scale field trials conducted from 2019 to 2022 in Quebec (Canada) demonstrated significant reductions in D. radicum infestations in radish and daikon crops. Quality control measures confirmed the effectiveness of sterilization on cabbage maggot, with minimal impact on male performance. The results suggest that the SIT is a promising, environmentally friendly alternative to chemical control for cabbage maggot management. The study further highlights the importance of optimizing release strategies and improving predictive models to guide deployment. Overall, the SIT offers growers a viable option to reduce reliance on insecticides while maintaining crop health and yield.
Homing gene drive strains for genetic suppression of agricultural insect pests
35331Yadav, Amarish K.; Tarrand, Ariel E.; Scott, Maxwell J., Entomologia Generalis, 45:1577 - 1590. 2025-12-04 14:52:03.
Agricultural insect pests cause substantial losses in crop productivity each year. Genetic-based strategies provide economical and environmentally friendly ways to limit pests that reproduce sexually. In contrast to conventional genetic methods (e.g. SIT), homing gene drives (HGDs) are potentially capable of suppressing or modifying an entire pest population in a short period of time after releasing a small number of HGD insects. The advent of CRISPR/Cas gene editing tools has simplified the engineering of gene drives, and the progress made on HGDs in various insects in the recent past is encouraging. However, to date HGDs have been developed and evaluated in only a few agricultural pest species. These drives have been designed to suppress populations by targeting genes essential for female development or fertility. Homing gene drive relies on homology directed repair (HDR) of the Cas9-mediated double-stranded DNA break in germ cells. Consequently, the use of other DNA repair pathways such as non-homologous end joining (NHEJ) and micro-homology mediated end joining (MMEJ) can retard homing. Further, establishment of functional resistant alleles through these end-joining pathways is one of the major challenges associated with HGDs. Development of HGDs in some pest species is challenging due to the technical difficulties of making transgenics. Identification and characterization of germline-specific promoters and other regulatory elements to achieve precise HDR (in early meiosis) can facilitate efficient homing. In this review, we highlight the recent progress made towards developing HGDs in agricultural insect pests with insights gained from studies in model organisms (e.g. Drosophila melanogaster).
Cattle Q&A with Brinda Dass, GeneConvene Global Collaborative
35243Tyrell Marchant, Progressive Cattle, 2025-10-15 08:41:35.
What factors have led to the northward spread of New World screwworm (NWS) over the past year after so many decades of successful eradication in Mexico and the U.S.? DASS: The northward spread of NWS after decades of eradication reflects a convergence of biological, environmental and programmatic factors. Climate change and increasing temperatures have created favorable conditions for pupal survival and year-round reproduction, enabling rapid reinvasion from subtropical regions. NWS biology – especially females’ ability to lay multiple waves of eggs in wounds – allows populations to surge quickly even from small footholds. High-density livestock practices and insufficient inspection of animal trade further accelerate spread, with smuggling through the Darién Gap undermining surveillance. Wildlife, pets and humans act as reservoirs, compounding detection challenges. Sterile insect technique (SIT), historically successful, has been overwhelmed: Production of sterile flies cannot match population growth, forcing control lines northward. Budget constraints, political disputes and reduced funding have further weakened monitoring and response systems. Together, these dynamics explain how a long-maintained eradication barrier collapsed, allowing NWS to expand northward at alarming speed.
Exploring experts’ uncertainties about gene drive technology for agricultural pest control in the U.S.: a qualitative study to inform innovation and decision-making
35241Barry, N., Barnhill, S.K. & Johnson, B.B., Environment Systems and Decisions, 45. 2025-10-15 08:34:10.
As experts consider what it might look like for gene drives to manage agricultural pests, there remain several uncertainties across a broad range of issues, including technical, ecological, regulatory, and social implications. Drawing on 25 expert interviews, we parse out these uncertainties and the potential for Adaptive Management to help guide development, deployment, and governance of gene drives for invasive agricultural pest management. Adaptive Management emerged specifically to attend to uncertainties in complex social-ecological systems, prescribing collective learning and responsiveness to stakeholder feedback to effectively reach management goals. Thus, Adaptive Management provides clear direction on how to account for and make decisions in the face of considerable uncertainties surrounding these gene drive tools. We also give some attention to the ways in which the uncertainties that are specific to agricultural applications are somewhat distinct from or consistent with global discourse around gene drive development across sectors.
Fruit fly tests in Greece target invasive species threat
35161Vassilis Kyriakoulis, Phys.org, 2025-09-15 15:24:50.
In a small persimmon orchard in northern Greece, scientists carefully open paper bags to release thousands of flies, in an experiment aimed at blunting the destructive impact of invasive new species. The insects are sterile male Mediterranean fruit flies (Ceratitis capitata), a pest that annually causes significant damage to crops in Naousa, where a large proportion of Greece's prominent export, the peach, is produced. But the project is ultimately aimed at curbing an even greater threat: fruit fly species from Asia, which have begun to make their appearance in southeastern Europe as climate change increases local temperatures. The four-year, EU-funded project titled REACT brings together researchers from 12 different countries including the UK, Israel and South Africa. The program has a budget of 6.65 million euros ($7.8 million). "Our approach is to locally eradicate Mediterranean fruit fly populations and then apply this knowledge to other species of interest, such as the oriental fruit fly and the peach fruit fly," said project participant Nikos Papadopoulos, a professor of Applied Entomology at the University of Thessaly. The male flies are grown at the University of Patras and are fed a bacterial supplement that makes them more active, resilient, and competitive, said George Tsiamis, the university's Laboratory of Microbiology Systems director, during a media tour organized in Naousa by the research team.
The shibirets4 mutation causes temperature sensitive paralytic and lethal phenotypes in the Queensland fruit fly, Bactrocera tryoni
35094Anzu Okada, Mamoru Okamoto, Thu N.M. Nguyen, et al., Insect Science, 2025-09-01 19:43:43.
Bactrocera tryoni, the Queensland fruit fly, is among the most damaging insect pests to the Australian horticultural industry as larvae infest ripening fruits or vegetables prior to harvest. Genetic biocontrol using Sterile Insect Technique (SIT) programs have been used to successfully suppress populations, via mass release of factory-reared sterile males that mate with wild females. Bi-sex flies are currently used for releases, although the efficiency of these control programs could be improved through using genetic sexing strains that eliminate females early during development, as they are not required for SIT. Here we used CRISPR/Cas9 mutagenesis to modify two nucleotides in the B. tryoni gene shibire, which created a proline to serine amino acid substitution and produced a temperature sensitive phenotype. Shibire is an essential GTPase required in endocytosis and synaptic vesicle recycling, and classical mutagenic screens in the vinegar fly Drosophila melanogaster previously identified temperature sensitive alleles including shits4 that results in adult paralysis. In B. tryoni, the shits4 mutant strain exhibited similar adult paralytic phenotypes when exposed to high temperatures, as well as temperature dependent lethality at egg, larval and pupal stages when subjected to heat treatment above standard rearing temperatures. These temperature sensitive phenotypes could be adapted to develop a SIT genetic sexing strain for conditional elimination of females prior to sterile releases, to improve efficiency and reduce costs.
Synthetically Assisted Conservation and the Application of Emerging Biological Technologies for the Protection of Biodiversity
34956Jedediah F. Brodie, Amanda Emmel, Blake Wiedenheft, et al., Conservation Letters, 8. 2025-07-08 13:20:29.
New tools of synthetic biology that enable precise manipulation of genomes, metabolic pathways, and ecosystems present new opportunities, risks, ethical dilemmas, and responsibilities for stewards of biodiversity. We argue that the risks and benefits of synthetic biology for use in biodiversity conservation, which we term “synthetically assisted conservation,” can be better understood, evaluated, and regulated by precisely defining the techniques in relation to well-established and regulated conservation frameworks: conservation translocation and integrated pest management. Synthetically assisted conservation translocation could include the release of genetically modified organisms for in situ conservation of genes or restoration of ecological functions, while a synthetically assisted application of integrated pest management could involve using genetic modifications propagated through gene drives to remove invasive species. Contextualizing the range of techniques as expansions of these frameworks clarifies how new approaches may impact conservation, facilitating risk assessment and responsible implementation. Decision-making may be informed by existing policy guidance in accordance with national and international regulations on conservation translocation and integrated pest management. Nevertheless, additional policy and evaluative guidelines are needed to keep pace with rapid technological growth and novel issues such as the release of genes (e.g., in pollen or marine-dispersed gametes) separate from live organisms.
Unlocking Gene Drive in Agriculture
34897Sarah Lee, Number Analytics, 2025-06-06 08:31:38.
Gene drive is a revolutionary genetic engineering technique that has the potential to transform the field of agricultural biotechnology. In this section, we will explore the definition, mechanism, and history of gene drive technology, as well as its potential applications in agriculture. Gene drive is a naturally occurring phenomenon where a particular gene or set of genes is inherited at a higher rate than expected under normal Mendelian inheritance. This is achieved through the use of CRISPR-Cas9 genome editing technology, which enables scientists to selectively modify genes and drive them through a population at an exponential rate. The mechanism of gene drive involves the following steps: Target gene identification: Scientists identify a target gene that they want to drive through a population. CRISPR-Cas9 editing: The CRISPR-Cas9 system is used to edit the target gene and introduce a gene drive element. Gene drive inheritance: The gene drive element is inherited by offspring at a higher rate than expected, leading to the spread of the modified gene through the population.
The Future of Gene Drive in Farming
34895Sarah Lee, Number Analytics, 2025-06-06 08:25:42.
The advent of gene drive technology has opened up new avenues for transforming farming practices, improving crop yields, and promoting sustainability. Gene drive is a genetic engineering technique that allows for the rapid spread of a particular gene or trait through a population, potentially revolutionizing the way we approach crop improvement and pest management. In this article, we will explore the latest advancements in gene drive technology and its potential to shape the future of farming. Gene drive has the potential to significantly improve crop yields and nutritional content by introducing desirable traits such as pest resistance, drought tolerance, and enhanced nutritional profiles. The development of pest-resistant crops, for instance, could reduce the need for pesticides, minimizing the environmental impact of farming practices. Gene drive can be used to introduce genes that confer resistance to pests and diseases, reducing crop losses and improving yields. For example, scientists have used gene drive to develop mosquitoes that are resistant to malaria. Similarly, gene drive can be used to enhance the nutritional content of crops, such as by introducing genes that increase the production of essential micronutrients like vitamin A.
Progress made for blackchin tilapia control in Thailand
34535The Fish Site, 2025-02-21 11:50:45.
Despite tilapia being one of the most widely farmed fish in the global aquaculture industry, invasive populations of the blackchin tilapia - a cichlid native to West Africa - have been devastating the productivity of aquaculture operations throughout Thailand. However, a multi-stakeholder effort led by the country's Department of Fisheries has reported progress towards controlling this invasive species, turning an environmental challenge into a pathway for sustainable development and local economic growth. Forming part of a five-point government strategy to address the ecological challenges posed by invasive species, the Department of Fisheries has developed a specially engineered strain known as Blackchin Tilapia 4n - a genetically modified variant designed to inhibit reproduction. The experimental strain has been released at experimental sites this month to evaluate its effectiveness in reducing the invasive fish population. Simultaneously, another project is specifically geared towards assisting aquaculture producers. The Seabass Fund for Farmers assists farmers in reducing costs by introducing natural predators into aquaculture ponds, effectively managing the blackchin tilapia population. This programme was established by the Phetchaburi Provincial Fisheries Office to support small-scale farmers with revolving funds for purchasing seabass fingerlings, providing a sustainable solution for shrimp, fish, and crab farmers operating in semi-natural systems to control and reduce populations of the invasive cichlid. In addition to direct eradication efforts, the promotion of blackchin tilapia products, such as foods and feeds, is being used to encourage consumption of the fish, driving local economic growth. These initiatives have been implemented by Charoen Pokphand Foods throughout 2024, including the purchase of 2 million kilograms of Blackchin tilapia for fishmeal production. Charoen Pokphand has also extended assistance to fishing activities aimed at blackchin tilapia removal by supplying fishing equipment and necessary materials to participants. If successful, these programmes for the control of blackchin tilapia populations in Thailand could serve as a model for governmental and private-sector cooperation for environmental solutions and local economic development.
Antagonistic kinesin-14s within a single chromosomal drive haplotype
34531Meghan J. Brady, Anjali Gupta, Jonathan I. Gent, et al., bioRxiv, 2025-02-21 10:31:41.
In maize, there are two meiotic drive systems that operate on large tandem repeat arrays called knobs that are found on chromosome arms. One meiotic drive haplotype, Abnormal chromosome 10 (Ab10), encodes two kinesin proteins that interact with two distinct tandem repeat arrays in a sequence-specific manner to confer meiotic drive. The kinesin KINDR associates with knob180 repeats while the kinesin TRKIN associates with TR-1 repeats. Prior data show that meiotic drive is conferred primarily by the KINDR/knob180 system, with the TRKIN/TR-1 system having little or no role. The second meiotic drive haplotype, K10L2, shows low levels of meiotic drive and only encodes the TRKIN/TR-1 system. Here we used long-read sequencing to assemble the K10L2 haplotype and showed that it has strong homology to an internal portion of the Ab10 haplotype. We also carried out CRISPR mutagenesis of Trkin to test the role of Trkin on Ab10 and K10L2. The data indicate that the Trkin gene on Ab10 does not improve drive or fitness but instead has a weak deleterious effect when paired with a normal chromosome 10. The deleterious effect is more severe when Ab10 is paired with K10L2: in this context functional Trkin on either chromosome nearly abolishes Ab10 drive. We modeled the effect of Trkin on Ab10 and found it should not persist in the population. We conclude that Trkin either confers an advantage to Ab10 in untested circumstances or that it is in the process of being purged from the Ab10 population.
Mechanisms, Machinery, and Dynamics of Chromosome Segregation in Zea mays
34244Duffy, Marissa E., Michael Ngaw, Shayna E. Polsky, et al., Genes, 15. 2025-01-12 21:25:37.
Zea mays (maize) is both an agronomically important crop and a powerful genetic model system with an extensive molecular toolkit and genomic resources. With these tools, maize is an optimal system for cytogenetic study, particularly in the investigation of chromosome segregation. Here, we review the advances made in maize chromosome segregation, specifically in the regulation and dynamic assembly of the mitotic and meiotic spindle, the inheritance and mechanisms of the abnormal chromosome variant Ab10, the regulation of chromosome–spindle interactions via the spindle assembly checkpoint, and the function of kinetochore proteins that bridge chromosomes and spindles. In this review, we discuss these processes in a species-specific context including features that are both conserved and unique to Z. mays. Additionally, we highlight new protein structure prediction tools and make use of these tools to identify several novel kinetochore and spindle assembly checkpoint proteins in Z. mays.
Kenya Set to Introduce GMO Maize After Public Consultation Period
34217Martin Olage, Mwakilishi, 2025-01-07 20:44:12.
The National Biosafety Authority (NBA) has completed a month-long public consultation regarding the potential market introduction of Genetically Modified (GM) maize, specifically known as BT Maize. This consultation, initiated in mid-December after an official notice on December 6, 2024, gathered feedback from Kenyan citizens as part of its due diligence process. This initiative follows a licensing request made by the Kenya Agricultural and Livestock Research Organisation (Kalro) and the African Agricultural Technology Foundation (AATF). The organizations aim to bring BT Maize—developed by Bayer Company and licensed to the TELA Maize project—into the market. This genetically modified maize is engineered to resist pests such as stem borers and fall armyworms, potentially decreasing the reliance on chemical insecticides in agriculture. Historically, Kenya has cultivated genetically modified crops for non-food purposes, including BT Cotton. The NBA has been active in conducting field trials with various GM crops: these include water-efficient maize in Makueni, enhanced maize suited for African agricultural conditions in Kitale, and virus-resistant sweet potatoes and cassava in Kakamega and Thika. Current trials are also evaluating GM potatoes in Nakuru and Kiambu, along with the cultivation of purple gypsophilia flowers in Naivasha. Kalro and AATF advocate that BT Maize presents a vital solution for minimizing crop damage caused by pests. They stress that the maize contains specific genes sourced from Bacillus thuringiensis, effectively targeting particular lepidopteran pests.
Selfing Promotes Spread and Introgression of Segregation Distorters in Hermaphroditic Plants
30952Hongru Wang, Léo Planche, Vladimir Shchur, Rasmus Nielsen, Molecular Biology and Evolution, 41. 2024-07-25 19:02:11.
Segregation distorters (SDs) are genetic elements that distort the Mendelian segregation ratio to favor their own transmission and are able to spread even when they incur fitness costs on organisms carrying them. Depending on the biology of the host organisms and the genetic architecture of the SDs, the population dynamics of SDs can be highly variable. Inbreeding is considered an effective mechanism for inhibiting the spread of SDs in populations, and can evolve as a defense mechanism against SDs in some systems. However, we show that inbreeding in the form of selfing in fact promotes the spread of SDs acting as pollen killers in a toxin–antidote system in hermaphroditic plants by two mechanisms: (i) By reducing the effective recombination rate between killer and antidote loci in the two-locus system and (ii) by increasing the proportion of SD alleles in individual flowers, rather than in the general gene-pool. We also show that in rice (Oryza sativa L.), a typical hermaphroditic plant, all molecularly characterized SDs associated with pollen killing were involved in population hybridization and have introgressed across different species. Paradoxically, these loci, which are associated with hybrid incompatibility and can be thought of as Bateson–Dobzhansky–Muller incompatibility loci are expected to reduce gene-flow between species, in fact cross species boundaries more frequently than random loci, and may act as important drivers of introgression.
Chinese researchers make genetic breakthrough that could change the future of agriculture: ‘Powerful and transformative strategy’
30945Jeremiah Budin, The Cool Down, 2024-07-25 18:38:42.
Chinese scientists have reportedly engineered a way to use gene-editing technology to bypass natural plant behavior and force crops to inherit genes that will make them more resilient and easier to grow, according to Interesting Engineering. "The genetic manipulation of wild plant populations has emerged as a potentially powerful and transformative strategy," the researchers said. The technique involves using CRISPR gene-editing technology to bypass traditional Mendelian inheritance — the process by which genes are passed down through generations — to breed plants with "ideal" genes. The system is known as CRISPR-Assisted Inheritance, or CAIN. "This gene drive-based approach thus seeks to balance crop protection and environmental considerations to minimise the loss of biodiversity while optimising productivity," the researchers wrote. "As we venture into this new frontier in genetic engineering, [CAIN] and other gene drive systems could reshape ecological management and agricultural practices."
Gene Drives Shown to Work in Wild Plants. They Could Wipe Out Weeds.
30936Shelly Fan, Singularity Hub, 2024-07-24 15:57:21.
Henry Grabar has had enough battling knotweed. All he wanted was to build a small garden in Brooklyn—a bit of peace amid the cacophony of city life. But a plant with beet-red leaves soon took over his nascent garden. The fastest growing plant he’d ever seen, it could sprout up to 10 feet high and grow thick as a cornfield. Even with herbicide, it was nearly impossible to kill. Invasive plant species and weeds don’t just ruin backyard gardens. Weeds decrease crop yields at an average annual cost of $33 billion, and control measures can rack up $6 billion more. Herbicides are a defense, but they have their own baggage. Weeds rapidly build resistance against the chemicals, and the resulting produce can be a hard sell for many consumers. Weeds often seem to have the upper hand. Can we take it away? Two recent studies say yes. Using a technology called a synthetic gene drive, the teams spliced genetic snippets into a mustard plant popular in lab studies. Previously validated in fruit flies, mosquitoes, and mice, gene drives break the rules of inheritance, allowing “selfish” genes to rapidly spread across entire species. But making gene drives work in plants has been a headache, in part due to the way they repair their DNA. The new studies found a clever workaround, leading to roughly 99 percent propagation of a synthetic genetic payload to subsequent generations, in contrast to nature’s 50 percent. Computer models suggest the gene drives could spread throughout an entire population of the plant in roughly 10 to 30 generations. Overriding natural evolution, gene drives could add genes that make weeds more vulnerable to herbicides or reduce their pollination and numbers. Beneficial genes can also spread across crops—essentially fast-tracking the practice of cross-breeding for desirable traits.
A New CRISPR-Driven Technology for Gene Drive in Plants
30849Lori Dajose, CalTech, 2024-06-28 11:49:31.
Spreading a specific genetic trait through a population, even if that trait does not benefit those who carry it, is the purpose of a "gene drive." Gene drives can be used for many different applications. These are divided into two broad categories: population modification and population suppression. Population modification can make mosquitos immune to, and therefore unable to spread, malaria, or make a crop more heat-tolerant in anticipation of climate change. Population suppression can be used to bring about local reduction or elimination of a weed or invasive species. But any gene editing program needs to have strict built-in controls to keep the modifications localized to a specific area and to prevent other species from accidentally inheriting modified genes. Now, Caltech researchers have developed a new gene drive technology, called ClvR (pronounced "cleaver"), that can be specifically customized to plant species, preventing accidental gene editing in cross-pollination situations. Crucially, the technology can be designed to be self-limiting, only spreading the desired genes for a limited number of generations, thereby limiting their spread in time and space. The work is the first engineered gene drive in plants and the first to enable species-specific modification as well as the first to act at the level of plant sex cells.
First synthetic gene drive for plants could help eradicate weeds
30846Erik Stokstad, Science, 2024-06-28 11:39:25.
More than a decade ago, a research group used the genome editor CRISPR to put evolution on fast forward, spurring a gene to spread throughout a population of lab-reared fruit flies many times faster than it normally could in nature. Mosquitoes with CRISPR-based “gene drives” came soon after, then mice a few years later—advances that brought a fraught mix of technological promise and ethical complexity. Proponents tout gene drives as a way to prevent insect-borne diseases, wipe out rats and other invasive creatures, and even help prevent extinction of endangered species. But one set of organisms had stood apart from the excitement: plants. Now, geneticists report that synthetic gene drives can work in flora, too. Circumventing a long-standing hurdle, two teams have independently engineered Arabidopsis thaliana, a small mustard popular for lab work, to carry a genetic payload that is inherited by up to 99% of offspring. Modeling suggests a similar gene could permeate a natural plant population in 10 to 30 generations. “What they’ve achieved is pretty amazing,” says Paul Neve, a weed scientist at the University of Copenhagen. “It is clever and innovative.”
Benefits and risks of gene drives for invasive plant management – the case for common tansy
28162L. Croghan, A. G. Smith, M. A. Tancos, N. O. Anderson and R. L. Becker, Frontiers in Agronomy, 5. 2023-10-20 12:05:59.
Invasive plants cause significant environmental and economic damage, but land managers have few control options. Common tansy (Tanacetum vulgare) is prevalent in many US states and is one of the most reported invasive plants in Minnesota. Controlling common tansy poses a challenge due to its extensive distribution and association with diverse plant communities. A gene drive is being explored as a genetic biocontrol method for the management of several non-native invasives, including common tansy in North America. Gene drives have emerged as a novel biotechnology application with potential to improve public health, promote conservation, and increase agricultural productivity. In common tansy, gene drives could be developed to target genes that would reduce or eliminate female fertility and consequently inhibit common tansy seed production. Using common tansy as an example, we outline risks associated with the use of gene drive technology for invasive plant control and explain how risks may be mitigated. Understanding potential benefits and risks associated with gene drives in the early stages of development is crucial. Mitigating risks, receiving stakeholder input, and navigating the regulatory environment will play an important role in gene drive development and deployment.
Gene drive in plants emerges from infancy
28152M. J. A. Awan, R. Z. Naqvi, I. Amin and S. Mansoor, Trends in Plant Science, 2023-10-18 11:43:35.
Selfish genetic elements (SGEs) display biased transmission to offspring. However, their breeding potential has remained obscure. Wang et al. recently reported a natural gene-drive system that can be harnessed to prevent hybrid incompatibility and to develop a synthetic gene-drive (SGD) system for crop improvement.
Cleave and Rescue gamete killers create conditions for gene drive in plants
28140O. Georg, L. J. Michelle, I. Tobin and A. H. Bruce, bioRxiv, 2023.10.13.562303. 2023-10-14 10:23:38.
Gene drive elements promote the spread of linked traits, even when their presence confers a fitness cost to carriers, and can be used to change the composition or fate of wild populations. Cleave and Rescue (ClvR) drive elements sit at a fixed chromosomal position and include a DNA sequence-modifying enzyme such as Cas9/gRNAs (the Cleaver/Toxin) that disrupts endogenous versions of an essential gene, and a recoded version of the essential gene resistant to cleavage (the Rescue/Antidote). ClvR spreads by creating conditions in which those lacking ClvR die because they lack functional versions of the essential gene. We demonstrate the essential features of ClvR gene drive in the plant Arabidopsis thaliana through killing of gametes that fail to inherit a ClvR that targets the essential gene YKT61, whose expression is required in male and female gametes for their survival. Resistant (uncleavable but functional) alleles, which can slow or prevent drive, were not observed. Modeling shows plant ClvRs can be used to rapidly drive population modification or suppression. Possible applications in weed control, plant breeding and conservation are discussed.Competing Interest StatementThe authors have filed patent applications on ClvR and related technologies (U.S. Application No. 15/970,728 and No. 16/673,823).
Overriding Mendelian inheritance in Arabidopsis with a CRISPR toxin-antidote gene drive that impairs pollen germination
28101L. Yang, J. Bingke, C. Jackson and Q. Wenfeng, bioRxiv, 2023.10.10.561637. 2023-10-11 07:52:15.
Synthetic gene drives, inspired by natural selfish genetic elements, present transformative potential for disseminating traits that benefit humans throughout wild populations, irrespective of potential fitness costs. Here, we constructed a gene drive system called CRISPR-Assisted Inheritance utilizing NPG1 (CAIN), which employs a toxin-antidote mechanism in the male germline to override Mendelian inheritance in plants. Specifically, a gRNA-Cas9 cassette targets the essential No Pollen Germination 1 (NPG1) gene, serving as the toxin to block pollen germination. A recoded, CRISPR-resistant copy of NPG1 serves as the antidote, providing rescue only in pollen cells that carry the drive. To limit potential consequences of inadvertent release, we used self-pollinating Arabidopsis thaliana as a model. The drive demonstrated a robust 88-99% transmission rate over two successive generations, producing minimal resistance alleles that are unlikely to inhibit drive spread. Our study provides a strong basis for rapid genetic modification or suppression of outcrossing plant populations.Competing Interest StatementThe authors have declared no competing interest.
A natural gene drive element confers speciation in rice
28000Y. Li, S. Liu and R. Shen, Chinese Science Bulletin, 68:3400-3402. 2023-09-27 08:30:59.
For a long time, although many important advances have been made in the field of rice hybrid sterility, the specific molecular mechanism behind the "killer-protector"/ "poison-antidote" model has been unclear. Recently, the team of Academician Wan Jianmin of Nanjing Agricultural University identified a major locus RHS12 controlling pollen sterility of indica-japonica hybrids. This site belongs to the same locus as the recently cloned pf12 and Se[16,17]. Genetic analysis revealed that RHS12 consists of two closely linked genes, iORF3/DUYAO and iORF4/JIEYAO. These two genes are commonly found in indica rice genome, but not in some japonica rice genomes. iORF3 (DUYAO) encodes a poison protein localized in mitochondria. DUYAO interacts with OsCOX11, a core functional protein in the mitochondrial respiratory chain, to cause mitochondrial dysfunction and induce programmed cell death (program cell death, PCD) leading to pollen abortion. iORF4 (JIEYAO) encodes an antidote protein that interacts with the DUYAO protein to bring DUYAO to the autophagosome for degradation, thereby releasing OsCOX11 for normal pollen development (Fig. 1). Therefore, during the pollen development of indica-japonica hybrids, the pollen of japonica type without this pair of genes was selectively aborted, while the pollen of indica type with this pair of genes developed normally. For the first time, this study completely and clearly clarified the mechanism of RHS12 regulating rice hybrid sterility from the genetic, cellular and molecular levels, and achieved a major breakthrough in this field.
Using Wolbachia to control rice planthopper populations: progress and challenges
27976Y. Guo, J. Shao, Y. Wu and Y. Li, Frontiers in Microbiology, 14. 2023-09-14 07:43:50.
Wolbachia have been developed as a tool for protecting humans from mosquito populations and mosquito-borne diseases. The success of using Wolbachia relies on the facts that Wolbachia are maternally transmitted and that Wolbachia-induced cytoplasmic incompatibility provides a selective advantage to infected over uninfected females, ensuring that Wolbachia rapidly spread through the target pest population. Most transinfected Wolbachia exhibit a strong antiviral response in novel hosts, thus making it an extremely efficient technique. Although Wolbachia has only been used to control mosquitoes so far, great progress has been made in developing Wolbachia-based approaches to protect plants from rice pests and their associated diseases. Here, we synthesize the current knowledge about the important phenotypic effects of Wolbachia used to control mosquito populations and the literature on the interactions between Wolbachia and rice pest planthoppers. Our aim is to link findings from Wolbachia-mediated mosquito control programs to possible applications in planthoppers.
The role of conflict in shaping plant biodiversity
27753J. M. Coughlan, New Phytologist, 2023-09-04 07:45:46.
Although intrinsic postzygotic reproductive barriers can play a fundamental role in speciation, their underlying evolutionary causes are widely debated. One hypothesis is that incompatibilities result from genomic conflicts. Here, I synthesize the evidence that conflict generates incompatibilities in plants, thus playing a creative role in plant biodiversity. While much evidence supports a role for conflict in several classes of incompatibility, integrating knowledge of incompatibility alleles with natural history can provide further essential tests. Moreover, comparative work can shed light on the relative importance of conflict in causing incompatibilities, including the extent to which their evolution is repeatable. Together, these approaches can provide independent lines of evidence that conflict causes incompatibilities, cementing its role in plant speciation.
Meiotic segregation and post-meiotic drive of the Festuca pratensis B chromosome
27749R. Ebrahimzadegan, J. Fuchs, J. Chen, V. Schubert, A. Meister, A. Houben and G. Mirzaghaderi, Chromosome Research, 31:26. 2023-09-02 07:34:43.
In many species, the transmission of B chromosomes (Bs) does not follow the Mendelian laws of equal segregation and independent assortment. This deviation results in transmission rates of Bs higher than 0.5, a process known as “chromosome drive”. Here, we studied the behavior of the 103 Mbp-large B chromosome of Festuca pratensis during all meiotic and mitotic stages of microsporogenesis. Mostly, the B chromosome of F. pratensis segregates during meiosis like standard A chromosomes (As). In some cases, the B passes through meiosis in a non-Mendelian segregation leading to their accumulation already in meiosis. However, a true drive of the B happens during the first pollen mitosis, by which the B preferentially migrates to the generative nucleus. During second pollen mitosis, B divides equally between the two sperms. Despite some differences in the frequency of drive between individuals with different numbers of Bs, at least 82% of drive was observed. Flow cytometry-based quantification of B-containing sperm nuclei agrees with the FISH data.
Female meiotic drive in plants: mechanisms and dynamics
27709F. Finseth, Current Opinion in Genetics and Development, 82:102101. 2023-08-24 09:45:29.
Female meiosis is fundamentally asymmetric, creating an arena for genetic elements to compete for inclusion in the egg to maximize their transmission. Centromeres, as mediators of chromosomal segregation, are prime candidates to evolve via ‘female meiotic drive’. According to the centromere-drive model, the asymmetry of female meiosis ignites a coevolutionary arms race between selfish centromeres and kinetochore proteins, the by-product of which is accelerated sequence divergence. Here, I describe and compare plant models that have been instrumental in uncovering the mechanistic basis of female meiotic drive (maize) and the dynamics of active selfish centromeres in nature (monkeyflowers). Then, I speculate on the mechanistic basis of drive in monkeyflowers, discuss how centromere strength influences chromosomal segregation in plants, and describe new insights into the evolution of plant centromeres.
A natural gene drive system confers reproductive isolation in rice
27420C. Wang, J. Wang, J. Lu, Y. Xiong, Z. Zhao, X. Yu, X. Zheng, J. Li, Q. Lin, Y. Ren, Y. Hu, X. He, C. Li, Y. Zeng, R. Miao, M. Guo, B. Zhang, Y. Zhu, Y. Zhang, W. Tang, Y. Wang, B. Hao, Q. Wang, S. Cheng, X. He, B. Yao, J. Gao, X. Zhu, H. Yu, Y. Wang, Y. S, Cell, 2023-07-20 08:38:37.
Hybrid sterility restricts the utilization of superior heterosis of indica-japonica inter-subspecific hybrids. In this study, we report the identification of RHS12, a major locus controlling male gamete sterility in indica-japonica hybrid rice. We show that RHS12 consists of two genes (iORF3/DUYAO and iORF4/JIEYAO) that confer preferential transmission of the RHS12-i type male gamete into the progeny, thereby forming a natural gene drive. DUYAO encodes a mitochondrion-targeted protein that interacts with OsCOX11 to trigger cytotoxicity and cell death, whereas JIEYAO encodes a protein that reroutes DUYAO to the autophagosome for degradation via direct physical interaction, thereby detoxifying DUYAO. Evolutionary trajectory analysis reveals that this system likely formed de novo in the AA genome Oryza clade and contributed to reproductive isolation (RI) between different lineages of rice. Our combined results provide mechanistic insights into the genetic basis of RI as well as insights for strategic designs of hybrid rice breeding.
Teosinte Pollen Drive guides maize domestication and evolution by RNAi
27414B. Berube , E. Ernst, J. Cahn, B. Roche, C. d. S. Alves, A. Scheben, A. Siepel, J. Ross-Ibarra, J. Kermicle and R. Martienssen, bioRxiv, 2023.07.12.548689. 2023-07-13 08:27:36.
Meiotic drivers subvert Mendelian expectations by manipulating reproductive development to bias their own transmission. Chromosomal drive typically functions in asymmetric female meiosis, while gene drive is normally postmeiotic and typically found in males. Using single molecule and single-pollen genome sequencing, we describe Teosinte Pollen Drive, an instance of gene drive in hybrids between maize (Zea mays ssp. mays) and teosinte mexicana (Zea mays ssp. mexicana), that depends on RNA interference (RNAi). 22nt small RNAs from a non-coding RNA hairpin in mexicana depend on Dicer-Like 2 (Dcl2) and target Teosinte Drive Responder 1 (Tdr1), which encodes a lipase required for pollen viability. Dcl2, Tdr1, and the hairpin are in tight pseudolinkage on chromosome 5, but only when transmitted through the male. Introgression of mexicana into early cultivated maize is thought to have been critical to its geographical dispersal throughout the Americas, and a tightly linked inversion in mexicana spans a major domestication sweep in modern maize. A survey of maize landraces and sympatric populations of teosinte mexicana reveals correlated patterns of admixture among unlinked genes required for RNAi on at least 3 chromosomes that are also subject to gene drive in pollen from synthetic hybrids. Teosinte Pollen Drive likely played a major role in maize domestication and evolution, and offers an explanation for the widespread abundance of "self" small RNAs in the germlines of plants and animals.Competing Interest StatementThe authors have declared no competing interest.
Genome and Transcriptome Analyses Facilitate Genetic Control of Wohlfahrtia magnifica, a Myiasis-Causing Flesh Fly
27427Z. Jia, S. Hasi, D. Zhan, B. Hou, C. Vogl and P. A. Burger, Insects, 14. 2023-07-10 08:53:12.
Myiasis caused by Wohlfahrtia magnifica is a widespread parasitic infestation in mammals. The infested host suffers from damage as the developing larvae feed on its tissues. For the control of myiasis infestation, genetic methods have been shown to be effective and promising as an alternative to insecticides. Combining genome, isoform sequencing (Iso-Seq), and RNA sequencing (RNA-seq) data, we isolated and characterized two sex-determination genes, W. magnifica transformer (Wmtra) and W. magnifica transformer2 (Wmtra2), whose orthologs in a number of insect pests have been utilized to develop genetic control approaches. Wmtra transcripts are sex-specifically spliced; only the female transcript encodes a full-length functional protein, while the male transcript encodes a truncated and non-functional polypeptide due to the presence of the male-specific exon containing multiple in-frame stop codons. The existence of five predicted TRA/TRA2 binding sites in the male-specific exon and the surrounding intron of Wmtra, as well as the presence of an RNA-recognition motif in WmTRA2 may suggest the auto-regulation of Wmtra by its own protein interacting with WmTRA2. This results in the skipping of the male-specific exon and translation of the full-length functional protein only in females. Our comparative study in dipteran species showed that both the WmTRA and WmTRA2 proteins exhibit a high degree of similarity to their orthologs in the myiasis-causing blow flies. Additionally, transcriptome profiling performed between adult females and adult males reported 657 upregulated and 365 downregulated genes. Functional analysis showed that among upregulated genes those related to meiosis and mitosis Gene Ontology (GO) terms were enriched, while, among downregulated genes, those related to muscle cell development and aerobic metabolic processes were enriched. Among the female-biased gene set, we detected five candidate genes, vasa (vas), nanos (nanos), bicoid (bcd), Bicaudal C (BicC), and innexin5 (inx5). The promoters of these genes may be able to upregulate Cas9 expression in the germline in Cas9-based homing gene drive systems as established in some flies and mosquitoes. The isolation and characterization of these genes is an important step toward the development of genetic control programs against W. magnifica infestation.
Scientists are Gene-Editing Flies to Fight Crop Damage
26310E. Mullin, WIRED, 2023-06-28 07:28:35.
In greenhouses in Oregon last month, researchers with the US Department of Agriculture began testing one such approach: sterilized male flies. The gene-edited bugs, made by St. Louis–based biotech company Agragene, are meant to suppress wild fly populations. The idea is that if they were to be released into the environment, the sterilized males would mate with wild females, resulting in a fertility dead end. “We see this technology as being able to provide healthier fruit and vegetables without doing a lot of harm to the environment,” says Agragene CEO Bryan Witherbee. Scientists at the company used the DNA editing tool Crispr to knock out two essential genes in fly embryos—one involved in male reproduction and another with female development. As a result, only sterile males hatch while the females die. “You don’t want to release females into the population, because those are the ones that are doing the damage,” says Stephanie Gamez, director of research and development at Agragene.
To fight berry-busting fruit flies, researchers focus on sterilizing the bugs
25719M. Walling, KTAL News.com, 2023-06-13 09:42:56.
Paul Nelson is used to doing battle with an invasive fruit fly called the spotted wing drosophila, a pest that one year ruined more than half the berries on the Minnesota farm he and his team run. In recent years, they’ve cut their losses closer to 5%, but it’s been labor-intensive and expensive. “It’s a pest that if you’re not willing to stick the time into it, it’s going to take over your farm,” said Nelson, the head grower at Untiedt’s, a vegetable and fruit operation about an hour west of Minneapolis. Nelson and other growers may someday get a new tool as a result of research at North Carolina State University into the insects, which ruin the berries by laying their eggs in them and have been estimated to cost growers hundreds of millions of dollars annually. The researchers, using a concept called “gene drive,” manipulated the insects’ DNA so that the female offspring would be sterile, and the method they used to achieve it significantly reduced the chance that a population could rebound.
Wolbachia-based strategies for control of agricultural pests
25104J. T. Gong, T. P. Li, M. K. Wang and X. Y. Hong, Curr Opin Insect Sci, 101039:10.1016/j.cois.2023.101039. 2023-04-25 10:26:15.
Wolbachia-based incompatible insect technique (IIT) and pathogen blocking technique (PBT) have been shown to be effective at protecting humans from mosquito-borne diseases in the past decades. Population suppression based on IIT and population replacement based on PBT have become major field application strategies that have continuously been improved by the translational research on Wolbachia-transinfected mosquitoes. Similarly, Wolbachia-based approaches have been proposed for the protection of plants from agricultural pests and their associated diseases. However, a bottleneck in Wolbachia-based strategies for the control of agricultural pests is the need for methods to establish Wolbachia-transinfected insect lines. As a first step in this direction, we compare field control strategies for mosquitos with the potential strategies for agricultural pests based on Wolbachia. Our results show that there is a critical need for establishing productive insect lines and accumulating field test data.
Development of transgenic corn planthopper Peregrinus maidis that express the tetracycline transactivator
27707A. A. Patil, W. Klobasa, D. Espinoza-Rivera, O. Baars, M. D. Lorenzen and M. J. Scott, Insect Molecular Biology, 32:363-375. 2023-02-24 09:39:46.
Abstract The corn planthopper, Peregrinus maidis, is a vector of several maize viruses and is consequently a significant agricultural pest in many tropical and subtropical regions. As P. maidis has developed resistance to insecticides, the aim of this study was to develop transgenic P. maidis strains that could be used for future genetic biocontrol programs. To facilitate the identification of transgenic P. maidis, we isolated and characterized the promoters for the P. maidis ubiquitin-like and profilin genes. Transient expression assays with P. maidis embryos showed that both promoters were active. Transgenic lines were established using piggyBac vectors and fluorescent protein marker genes. The lines carried an auto-regulated tetracycline transactivator (tTA) gene, which has been widely used to establish conditional lethal strains in other insect species. The transgenic lines showed low levels of tTA expression but were viable on diet with or without doxycycline, which inhibits the binding of tTA to DNA. We discuss possible modifications to the tTA overexpression system that could lead to the successful development of conditional lethal strains. To our knowledge, this is the first report of a transgenic Hemiptera. The approach we have taken could potentially be applied to other Hemiptera and, for P. maidis, the technology will facilitate future functional genomics studies.
GeneConvene Global Collaborative Webinar Series | Emerging Gene Drive Systems 2023
24769David O'Brochta, 2023-02-22 15:50:48.
Gene drive systems are being engineered in the laboratory and in some cases shown to be effective at rapidly altering target-gene frequencies in experimental populations. Much of this foundational work has been conducted in insects in the laboratory. This webinar series will focus on emerging potential applications of gene drive technology in a wide variety of organisms. These webinars are intended to inform audiences of the rationale for these development efforts, the current state of research and development and outstanding challenges.
Gene Drive Technology With Agricultural Application Potential
24788R. Carmeli-Peslak, SeedWorld, 2023-02-22 09:51:36.
Gene drive technology, a genetic phenomenon that occurs in nature, causes a trait to spread in species through sexual reproduction over many generations. The inheritance rate is higher than the Mendelian rate which is 50%. Gene drives have been used for public health and conservation, but can potentially be used in multiple species, like agricultural pests according to a release. Weeds and pests have a negative impact on crops and their impact has caused interest in potentially using genetic techniques, like gene drive, to help control weeds and pests. Current insect pest control includes the use of pesticides which has helped to decrease food loss and waste. Research around new tools will help continue to protect crops and reduce food waste while also minimizing agriculture’s environmental footprint. These new tools and practices include gene editing techniques. Now in its early stages, gene-drive-based strategies are being research to help reduce agricultural pests. The gene-drive-based strategies will focus on both controlling pests that cause damage and spreading desired crop or livestock traits faster. A limitation with this strategy is that gene drives cannot work on asexually reproducing organisms. The strategy is also unsuitable for species that have longer generation times. While gene-drive-based strategies may not meet all the needs, but it is a helpful tool to continue to investigate.
How CRISPR could help save crops from devastation caused by pests
24675E. F. Merchant, MIT Technology Review, 2023-02-02 10:23:26.
Researchers are now looking to add cutting-edge technology to California’s anti-Pierce’s arsenal, by changing the genome of the glassy-winged sharpshooter so that it can no longer spread the bacterium. Such a solution is possible thanks to CRISPR gene-editing technology, which has made modifying the genes of any organism increasingly simple. The technique has been used in experiments in cancer immunotherapy, apple breeding, and—controversially—human embryos. Now a growing number of researchers are applying it to agricultural pests, aiming to control a range of insects that together destroy about 40% of global crop production each year. If successful, these efforts could reduce reliance on insecticides and provide an alternative to genetic modifications to crops. For now, these gene-edited insects are shut away in labs across the globe, but that is poised to change. This year, a US company expects to start greenhouse tests in conjunction with the US Department of Agriculture (USDA) of fruit-damaging insects made sterile using CRISPR. At the same time, scientists at government and private institutions are beginning to learn more about pest genetics and to make edits in more species.
Imperial startup Biocentis to develop genetic tech to control harmful insects
24673D. Silverman, Imperial College London, 2023-02-01 10:17:53.
The Imperial startup was founded in 2022 by Imperial researchers in partnership with technology-focused investment group Neurone to create a more effective and sustainable alternative to pesticides. While insects play an essential role in the global ecosystem, among the planet’s millions of insect species are some that spread devastating human diseases such as Dengue Fever and Zika virus, exacerbate food insecurity by spoiling up to 25% of crops, and reduce biodiversity by invading new ecosystems to the detriment of local species. At present, these harmful insect populations are controlled primarily with pesticides. But the growth of pesticide resistance is prompting control programmes to increase the dose and frequency of the toxic chemicals, causing increasing harm to bees and other non-target species.
Both male and female meiosis contribute to non-Mendelian inheritance of parental chromosomes in interspecific plant hybrids (Lolium x Festuca)
24833J. Majka, M. Glombik, A. Dolezalova, J. Knerova, M. T. M. Ferreira, Z. Zwierzykowski, M. Duchoslav, B. Studer, J. Dolezel, J. Bartos and D. Kopecky, NEW PHYTOLOGIST, 2023-01-19 08:34:11.
Some interspecific plant hybrids show unequal transmission of chromosomes from parental genomes to the successive generations. It has been suggested that this is due to a differential behavior of parental chromosomes during meiosis. However, underlying mechanism is unknown. We analyzed chromosome composition of the F-2 generation of Festuca x Lolium hybrids and reciprocal backcrosses to elucidate effects of male and female meiosis on the shift in parental genome composition. We studied male meiosis, including the attachment of chromosomes to the karyokinetic spindle and gene expression profiling of the kinetochore genes. We found that Lolium and Festuca homoeologues were transmitted differently to the F-2 generation. Female meiosis led to the replacement of Festuca chromosomes by their Lolium counterparts. In male meiosis, Festuca univalents were attached less frequently to microtubules than Lolium univalents, lagged in divisions and formed micronuclei, which were subsequently eliminated. Genome sequence analysis revealed a number of non-synonymous mutations between copies of the kinetochore genes from Festuca and Lolium genomes. Furthermore, we found that outer kinetochore proteins NDC80 and NNF1 were exclusively expressed from the Lolium allele. We hypothesize that silencing of Festuca alleles results in improper attachment of Festuca chromosomes to karyokinetic spindle and subsequently their gradual elimination.
Gene editing and agrifood systems
24291FAO, FAO, 2022-12-20 09:22:56.
Gene-editing technologies represent a promising new tool for plant and animal breeding in low- and middle-income countries. They enhance precision and efficiency over current breeding methods and could lead to rapid development of improved plant varieties and animal breeds. However, as for any new technology, they have their merits and demerits. There is, as yet, no international consensus regarding if and how gene-edited organisms should be regulated, and whether their release would fall under the regulatory framework of the Cartagena Protocol on Biosafety to the Convention on Biological Diversity. This science- and evidence-based Issue Paper on gene editing and agrifood systems presents a balanced discussion of the most pertinent aspects of gene editing, including the consequences for human hunger, human health, food safety, effects on the environment, animal welfare, socioeconomic impact and distribution of benefits. Intrinsic ethical concerns and issues of governance and regulation are addressed, and the roles of the public and private sectors, alone and in partnership, are summarized. Various scenarios are also presented for how gene editing might be used in the future to help transform agrifood systems.
Scientist Recommends Gene Drive Strategies Of Pest Control To Increase Food Security
24062L. Agbo, allnews, 2022-11-28 16:46:37.
A Nigerian scientist, Dr. Rose Gidado has recommended that Nigerian policymakers and farmers adopt the technology of a gene drive-based pest management technique in order to increase bumper harvest and food security.In an interview with NAN on Monday in Abuja, Gidado, the Deputy Director at the National Biotechnology Development Agency (NABDA) and the OFAB's Country Coordinator, made the statement.In order to attain food security, which would lead to national development, she claimed that Nigerian farmers needed to accept the use of gene drive technology for their seeds and food crops.“Gene drives are systems that warrant biased inheritance by improving the possibility of DNA sequence passing from one generation to the other via sexual reproduction and potentially throughout an entire population.“It is a modern biotechnology technique that alters the tendency of transmitting a specific allele from the natural 50 per cent probability by propagating a particular set of genes throughout a population,’’ Gidado said.
Improvement of Resistance in Plants Against Insect-Pests Using Genome Editing Tools
25205S. Bhat and S. Kumar, Genome Editing: Current Technology Advances and Applications for Crop Improvement, 2022-10-09 09:31:41.
During growth period plants are subjected to both biotic and abiotic stresses. Like other biotic stresses, insect-pests are the most serious challenge for the plants particularly in yield losses. Genome editing techniques are becoming an emerging technology bringing real revolution in genetic engineering and biotechnology. Editing of targeted gene provides ways to elucidate extensive ranges of aims for the improvement, protection, and increased yield of various crops. Researchers all over the world have unraveled the usage of numerous gene editing methods from endonuclease to CRISPR/Cas in various aspects of plants like plant growth and development, insect-pest control, and other biotic stresses. The key goal of this chapter is to highlight various techniques of genome editing approaches which can be used to develop resistance in plants against insect-pests. New crop-based methods that reiterate the effective utilization of these techniques in insect-pest management as well as plant in resistance against pests are highlighted. This chapter also highlights the implication of genome editing as well as framework for its specific regulation.
Toward product-based regulation of crops
23498F. Gould, R. M. Amasino, D. Brossard, C. R. Buell, R. A. Dixon, J. B. Falck-Zepeda, M. A. Gallo, K. E. Giller, L. L. Glenna, T. Griffin, D. Magraw, C. Mallory-Smith, K. V. Pixley, E. P. Ransom, D. M. Stelly and C. N. Stewart, Science, 377:1051-1053. 2022-09-02 19:04:01.
Current process-based approaches to regulation are no longer fit for purpose Much effort has been expended globally over the past four decades to craft and update country-specific and multinational safety regulations that can be applied to crops developed by genetic engineering processes, while exempting conventionally bred crops. This differentiation made some sense in the 1980s, but in light of technological advances, it is no longer scientifically defensible. In the coming decades, innovations in genetic engineering and modern ?conventional? processes of crop development will enable use of these approaches to alter more crops and more traits. Future governance of new plant varieties and foods, regardless of the processes and techniques used to develop them, will require new, scientifically sound assessment methodologies, developed in a manner acceptable to society. Here, we provide a rationale for one governance approach that moves away from current process-based regulation and uses newly developed molecular techniques that enable detailed characterization of the new crops and foods themselves.
Researchers propose new framework for regulating engineered crops
23506North Carolina State University, Phys Org, 2022-09-01 19:29:56.
A Policy Forum article published today in Science calls for a new approach to regulating genetically engineered (GE) crops, arguing that current approaches for triggering safety testing vary dramatically among countries and generally lack scientific merit—particularly as advances in crop breeding have blurred the lines between conventional breeding and genetic engineering. Rather than focusing on the methods and processes behind the creation of a GE crop to determine if testing is needed, a more effective framework would examine the specific new characteristics of the crop itself by using so-called "-omics" approaches, the article asserts. In the same way that biomedical sciences can use genomic approaches to scan human genomes for problematic mutations, genomics can be used to scan new crop varieties for unexpected DNA changes.
Precision Guided Sterile Males Suppress Populations of an Invasive Crop Pest
23453N. P. Kandul, J. Liu, A. Buchman, I. C. Shriner, R. M. Corder, N. Warsinger-Pepe, T. Yang, A. K. Yadav, M. J. Scott, J. M. Marshall and O. S. Akbari, GEN Biotechnology, 1:372-385. 2022-08-18 10:24:32.
The Drosophila suzukii invasion of western countries has created an immense agricultural and economic threat to crop production. Despite many attempts to suppress its population, D. suzukii continues to destroy soft-flesh fruits. Precision guided sterile insect technique (pgSIT) utilizes the accuracy of programmable CRISPR gene targeting to generate sterilized males that can be deployed to suppress populations. Here, we generate pgSIT in D. suzukii and empirically and mathematically demonstrate that sterilized males are fit, competitive, and can eliminate populations of D. suzukii. Altogether, we describe an efficient way to generate sterile D. suzukii for release and safe effective population suppression.
CRISPR-based technology targets global crop pest
23449University of California - San Diego, Phys Org, 2022-08-18 10:05:07.
Applying new CRISPR-based technology to a broad agricultural need, researchers at the University of California San Diego have set their aims on a worldwide pest known to decimate valuable food crops. Nikolay Kandul, Omar Akbari and their colleagues first demonstrated the precision-guided sterile insect technique, or pgSIT, in Drosophila melanogaster, the common fruit fly, in 2019. The technology, later adapted to mosquitoes, uses programmable CRISPR techniques to edit key genes that control sex determination and fertility. Under the new system, pgSIT-developed insect eggs are deployed into a targeted population and only sterile males hatch, resulting in a fertility dead end for that species. Kandul, Akbari and their colleagues have now adapted the technology for use in Drosophila suzukii, an invasive fruit fly (also known as the spotted-wing drosophila) responsible for millions of dollars in crop damage. The advancement is described in the journal GEN Biotechnology.
Reflection on the Challenges, Accomplishments, and New Frontiers of Gene Drives
23416M. Melesse Vergara, J. Labbé and J. Tannous, BioDesign Research, 2022:9853416. 2022-08-09 07:29:59.
Ongoing pest and disease outbreaks pose a serious threat to human, crop, and animal lives, emphasizing the need for constantgenetic discoveries that could serve as mitigation strategies. Gene drives are genetic engineering approaches discovered decadesago that may allow quick, super-Mendelian dissemination of genetic modifications in wild populations, offering hopes formedicine, agriculture, and ecology in combating diseases. Following itsfirst discovery, several naturally occurring selfishgenetic elements were identified and several gene drive mechanisms that could attain relatively high threshold populationreplacement have been proposed. This review provides a comprehensive overview of the recent advances in gene drive researchwith a particular emphasis on CRISPR-Cas gene drives, the technology that has revolutionized the process of genomeengineering. Herein, we discuss the benefits and caveats of this technology and place it within the context of natural genedrives discovered to date and various synthetic drives engineered. Later, we elaborate on the strategies for designing syntheticdrive systems to address resistance issues and prevent them from altering the entire wild populations. Lastly, we highlight themajor applications of synthetic CRISPR-based gene drives in different living organisms, including plants, animals, andmicroorganisms.
Rye B chromosomes differently influence the expression of A chromosome-encoded genes depending on the host species
23119A. Boudichevskaia, A. Fiebig, K. Kumke, A. Himmelbach and A. Houben, Chromosome Research, 2022-07-04 08:55:15.
The B chromosome (B) is a dispensable component of the genome in many species. To evaluate the impact of Bs on the transcriptome of the standard A chromosomes (A), comparative RNA-seq analyses of rye and wheat anthers with and without additional rye Bs were conducted. In both species, 5-6% of the A-derived transcripts across the entire genomes were differentially expressed in the presence of 2Bs. The GO term enrichment analysis revealed that Bs influence A chromosome encoded processes like "gene silencing"; "DNA methylation or demethylation"; "chromatin silencing"; "negative regulation of gene expression, epigenetic"; "post-embryonic development"; and "chromosome organization." 244 B chromosome responsive A-located genes in + 2B rye and + B wheat shared the same biological function. Positively correlated with the number of Bs, 939 and 1391 B-specific transcripts were identified in + 2B and + 4B wheat samples, respectively. 85% of B-transcripts in + 2B were also found in + 4B transcriptomes. 297 B-specific transcripts were identified in + 2B rye, and 27% were common to the B-derived transcripts identified in + B wheat. Bs encode mobile elements and housekeeping genes, but most B-transcripts were without detectable similarity to known genes. Some of these genes are involved in cell division-related functions like Nuf2 and might indicate their importance in maintaining Bs. The transcriptome analysis provides new insights into the complex interrelationship between standard A chromosomes and supernumerary B chromosomes.
DriverSEAT: A spatially-explicit stochastic modelling framework for the evaluation of gene drives in novel target species
23008M. Legros and L. G. Barrett, bioRxiv, 2022.06.13.496025. 2022-06-16 08:19:49.
Gene drives represent a potentially ground breaking technology for the control of undesirable species or the introduction of desirable traits in wild population, and there is strong interest in applying these technologies to a wide range of species across many domains including agriculture, health, conservation and biosecurity. There remains however considerable uncertainty regarding the feasibility and efficacy of gene drives in various species, based in particular on biological and ecological specificities of each target. In this paper we introduce DriverSEAT, a new spatial, modular modelling framework designed to assess the outcome of gene drives in a range of target species based on their specific ecological dynamics and genetics. In addition to the main structure and characteristics of the model, we present an example of its application on scenarios of genetic control of weeds, a potential candidate for gene drive control that presents significant challenges associated with plant population dynamics. We illustrate here how the results from DriverSEAT can inform on the potential value of gene drives in this specific context, and generally provide ecologically informed guidance for the development and feasibility of gene drives as a control method in new target species.Competing Interest StatementThe authors have declared no competing interest.
Natural and Engineered Sex Ratio Distortion in Insects
23010A. Compton and Z. Tu, Frontiers in Ecology and Evolution, 10. 2022-06-15 08:25:52.
Insects have evolved highly diverse genetic sex-determination mechanisms and a relatively balanced male to female sex ratio is generally expected. However, selection may shift the optimal sex ratio while meiotic drive and endosymbiont manipulation can result in sex ratio distortion (SRD). Recent advances in sex chromosome genomics and CRISPR/Cas9-mediated genome editing brought significant insights into the molecular regulators of sex determination in an increasing number of insects and provided new ways to engineer SRD. We review these advances and discuss both naturally occurring and engineered SRD in the context of the Anthropocene. We emphasize SRD-mediated biological control of insects to help improve One Health, sustain agriculture, and conserve endangered species.
Supergene potential of a selfish centromere
22893F. Finseth, K. Brown, A. Demaree and L. Fishman, Philos Trans R Soc Lond B Biol Sci, 377:20210208. 2022-06-13 06:07:46.
Selfishly evolving centromeres bias their transmission by exploiting the asymmetry of female meiosis and preferentially segregating to the egg. Such female meiotic drive systems have the potential to be supergenes, with multiple linked loci contributing to drive costs or enhancement. Here, we explore the supergene potential of a selfish centromere (D) in Mimulus guttatus, which was discovered in the Iron Mountain (IM) Oregon population. In the nearby Cone Peak population, D is still a large, non-recombining and costly haplotype that recently swept, but shorter haplotypes and mutational variation suggest a distinct population history. We detected D in five additional populations spanning more than 200 km; together, these findings suggest that selfish centromere dynamics are widespread in M. guttatus. Transcriptome comparisons reveal elevated differences in expression between driving and non-driving haplotypes within, but not outside, the drive region, suggesting large-scale cis effects of D's spread on gene expression. We use the expression data to refine linked candidates that may interact with drive, including Nuclear Autoantigenic Sperm Protein (NASP(SIM3)), which chaperones the centromere-defining histone CenH3 known to modify Mimulus drive. Together, our results show that selfishly evolving centromeres may exhibit supergene behaviour and lay the foundation for future genetic dissection of drive and its costs. This article is part of the theme issue 'Genomic architecture of supergenes: causes and evolutionary consequences'.
Retraction Note: Selective inheritance of target genes from only one parent of sexually reproduced F1 progeny in Arabidopsis
22794T. Zhang, M. Mudgett, R. Rambabu, B. Abramson, X. Dai, T. P. Michael and Y. Zhao, Nature Communications, 13:3270. 2022-06-07 08:36:48.
Retraction to: Nature Communications https://doi-org.proxy-um.researchport.umd.edu/10.1038/s41467-021-24195-5, published online 22 June 2021.We retract the article cited above because genotyping results from recent experiments are not consistent with the conclusions presented in the paper.We recently genotyped a selection of F2 plants in order to identify plants to use for an introgression experiment.In the original study, we confirmed homozygosity by using a pair of oligonucleotides covering the large gene drive region in its entirety, a region that is too large to be amplified by PCR if both alleles have integrated the gene drive element. When we analyzed F2 plants using a pair of oligonucleotides targeting a smaller region of the gene drive, we found a small fragment was amplified only in about 75% of the plants. The absence of the band in the remaining F2 plants can be accounted for by a large NHEJ based deletion in one of the alleles of the F1 plants, which can result in the removal of the oligonucleotide binding sites. Thus, the F1 plants presented in the paper are not homozygous as stated in the published paper.In light of the new genotyping data that invalidate our conclusions on gene drives, we are retracting the paper. The gene targeting results of both the CRY1 lines and NPY5-GFP lines remain valid. We apologize for any inconvenience the publication of this work may have caused to the scientific community. All authors agree to the retraction.
The maize abnormal chromosome 10 meiotic drive haplotype: a review
22690R. K. Dawe, Chromosome Research, 2022-06-02 14:35:18.
The maize abnormal chromosome 10 (Ab10) haplotype encodes a meiotic drive system that converts heterochromatic knobs into centromere-like bodies that are preferentially segregated through female meiosis. Ab10 was first described in the 1940s and has been intensively studied. Here I provide a comprehensive review of the literature, starting from the discovery of knobs and Ab10, preceding through the classic literature, and finishing with molecular structure and mechanisms. The defining features of the Ab10 haplotype are its two specialized kinesins, Kinesin driver and TR-1 kinesin, that activate neocentromeres at knobs containing different classes of the tandem repeat. In most Ab10 haplotypes, the two kinesin/knob systems cooperate to promote maximum meiotic drive. However, recent interpretations suggest that each kinesin/knob system can function as an independent meiotic driver and that in some cases they compete with each other. Ab10 is present at low frequencies throughout the genus Zea and has significantly expanded genome size by promoting the formation of knobs throughout the genome.
Recent advancements in CRISPR/Cas technology for accelerated crop improvement
21827D. Das, D. L. Singha, R. R. Paswan, N. Chowdhury, M. Sharma, P. S. Reddy and C. Chikkaputtaiah, Planta, 255:109. 2022-04-25 09:34:49.
The likelihood of reduced agricultural production due to highly turbulent climatic conditions increases as the global population expands. The second paradigm of stress-resilient crops with enhanced tolerance and increased productivity against various stresses is paramount to support global production and consumption equilibrium. Although traditional breeding approaches have substantially increased crop production and yield, effective strategies are anticipated to restore crop productivity even further in meeting the world’s increasing food demands. CRISPR/Cas, which originated in prokaryotes, has surfaced as a coveted genome editing tool in recent decades, reshaping plant molecular biology in unprecedented ways and paving the way for engineering stress-tolerant crops. CRISPR/Cas is distinguished by its efficiency, high target specificity, and modularity, enables precise genetic modification of crop plants, allowing for the creation of allelic variations in the germplasm and the development of novel and more productive agricultural practices. Additionally, a slew of advanced biotechnologies premised on the CRISPR/Cas methodologies have augmented fundamental research and plant synthetic biology toolkits. Here, we describe gene editing tools, including CRISPR/Cas and its imitative tools, such as base and prime editing, multiplex genome editing, chromosome engineering followed by their implications in crop genetic improvement. Further, we comprehensively discuss the latest developments of CRISPR/Cas technology including CRISPR-mediated gene drive, tissue-specific genome editing, dCas9 mediated epigenetic modification and programmed self-elimination of transgenes in plants. Finally, we highlight the applicability and scope of advanced CRISPR-based techniques in crop genetic improvement.
Biotechnological Road Map for Innovative Weed Management
22450A. C. S. Wong, K. Massel, Y. Lam, J. Hintzsche and B. S. Chauhan, Frontiers in Plant Science, 13. 2022-04-25 09:27:40.
In most agriculture farmlands, weed management is predominantly reliant on integrated weed management (IWM) strategies, such as herbicide application. However, the overuse and misuse of herbicides, coupled with the lack of novel active ingredients, has resulted in the uptrend of herbicide-resistant weeds globally. Moreover, weedy traits that contribute to weed seed bank persistence further exacerbate the challenges in weed management. Despite ongoing efforts in identifying and improving current weed management processes, the pressing need for novel control techniques in agricultural weed management should not be overlooked. The advent of CRISPR/Cas9 gene-editing systems, coupled with the recent advances in “omics” and cheaper sequencing technologies, has brought into focus the potential of managing weeds in farmlands through direct genetic control approaches, but could be achieved stably or transiently. These approaches encompass a range of technologies that could potentially manipulate expression of key genes in weeds to reduce its fitness and competitiveness, or, by altering the crop to improve its competitiveness or herbicide tolerance. The push for reducing or circumventing the use of chemicals in farmlands has provided an added incentive to develop practical and feasible molecular approaches for weed management, although there are significant technical, practical, and regulatory challenges for utilizing these prospective molecular technologies in weed management.
The non-Mendelian behavior of plant B chromosomes
21722J. Chen, J. A. Birchler and A. Houben, Chromosome Res, 2022-04-12 09:30:19.
B chromosomes, also known as supernumerary chromosomes, are dispensable elements in the genome of many plants, animals, and fungi. Many B chromosomes have evolved one or more drive mechanisms to transmit themselves at a higher frequency than predicted by Mendelian genetics, and these mechanisms counteract the tendency of non-essential genetic elements to be lost over time. The frequency of Bs in a population results from a balance between their effect on host fitness and their transmission rate. Here, we will summarize the findings of the drive process of plant B chromosomes, focusing on maize and rye.
B-A Chromosome Translocations Possessing an A Centromere Partly Overcome the Root-Restricted Process of Chromosome Elimination in Aegilops speltoides
21726D. Li, A. Ruban, J. Fuchs, H. Kang and A. Houben, Frontiers in Cell and Developmental Biology, 10. 2022-03-28 09:37:44.
Some eukaryotes exhibit dramatic genome size differences between cells of different organs, resulting from the programmed elimination of chromosomes. Aegilops speltoides is an annual diploid species from the Poaceae family, with a maximum number of eight B chromosomes (Bs) in addition to its inherent seven pairs of standard A chromosomes (As). The Bs of this species undergo precise elimination in roots early in embryo development. In areal parts of the plant, the number of Bs is stable. To affect the root restricted process of B chromosome elimination, we employed X-ray mutagenesis, and different types of restructured Bs were identified. Standard Bs were observed in all analyzed shoots of mutagenized plants, while B-A translocations were only observed in 35.7% of F1 plants. In total 40 different B variants inconsistently escaped the elimination process in roots. As a result, mosaicism of B chromosome variants was found in roots. Only a small B chromosome fragment fused to an A chromosome was stably maintained in roots and shoots across F1 to F3 generations. The absence of B-A translocation chromosomes possessing a derived B centromere in root cells implies that the centromere of the B is a key component of the chromosome elimination process.
CRISPR-mediated knockout of cardinal and cinnabar eye pigmentation genes in the western tarnished plant bug
21243C. C. Heu, R. J. Gross, K. P. Le, D. M. LeRoy, B. Fan, J. J. Hull, C. S. Brent and J. A. Fabrick, Scientific Reports, 12. 2022-03-22 06:19:14.
The western tarnished plant bug, Lygus hesperus, is a key hemipteran pest of numerous agricultural, horticultural, and industrial crops in the western United States and Mexico. A lack of genetic tools in L. hesperus hinders progress in functional genomics and in developing innovative pest control methods such as gene drive. Here, using RNA interference (RNAi) against cardinal (LhCd), cinnabar (LhCn), and white (LhW), we showed that knockdown of LhW was lethal to developing embryos, while knockdown of LhCd or LhCn produced bright red eye phenotypes, in contrast to wild-type brown eyes. We further used CRISPR/Cas9 (clustered regularly interspaced palindromic repeats/CRISPR-associated) genome editing to generate germline knockouts of both LhCd (Card) and LhCn (Cinn), producing separate strains of L. hesperus characterized by mutant eye phenotypes. Although the cardinal knockout strain Card exhibited a gradual darkening of the eyes to brown typical of the wild-type line later in nymphal development, we observed bright red eyes throughout all life stages in the cinnabar knockout strain Cinn, making it a viable marker for tracking gene editing in L. hesperus. These results provide evidence that CRISPR/Cas9 gene editing functions in L. hesperus and that eye pigmentation genes are useful for tracking the successful genetic manipulation of this insect.
Studying the active role of the maize B chromosome in the modulation of gene expression
21018University of Missouri, Phys Org, 2022-03-16 06:42:22.
A team of University of Missouri biologists has made a new discovery that provides novel insights into the function and properties of the maize B chromosome. The study was led by Dr. Xiaowen Shi and Dr. Hua Yang, postdoctoral fellows in the Birchler lab, and reported in the January 2022 issue of the Plant Journal. Apart from the 20 normal A chromosomes, maize contains a nonessential B chromosome that can be present or absent from some individuals within a population. This chromosome has properties that drive its transmission in populations despite being nonessential. The maize B chromosome has wide applications in various genetic studies, including experimental mapping, chromosomal dosage studies, chromosomal behavior, and genetic engineering of minichromosomes. Although the maize B chromosome was discovered nearly a century ago, it has been thought to be an essentially inert chromosome. However, little was known about the function and properties of the maize B chromosome.
A gene drive does not spread easily in populations of the honey bee parasite Varroa destructor
20173N. R. Faber, A. B. Meiborg, G. R. McFarlane, G. Gorjanc and B. A. Harpur, Apidologie, 52:1112-1127. 2022-01-25 09:13:37.
Varroa mites (Varroa destructor) are the most significant threat to beekeeping worldwide. They are directly or indirectly responsible for millions of colony losses each year. Beekeepers are somewhat able to control varroa populations through the use of physical and chemical treatments. However, these methods range in effectiveness, can harm honey bees, can be physically demanding on the beekeeper, and do not always provide complete protection from varroa. More importantly, in some populations varroa mites have developed resistance to available acaricides. Overcoming the varroa mite problem will require novel and targeted treatment options. Here, we explore the potential of gene drive technology to control varroa. We show that spreading a neutral gene drive in varroa is possible but requires specific colony-level management practices to overcome the challenges of both inbreeding and haplodiploidy. Furthermore, continued treatment with acaricides is necessary to give a gene drive time to fix in the varroa population. Unfortunately, a gene drive that impacts female or male fertility does not spread in varroa. Therefore, we suggest that the most promising way forward is to use a gene drive which carries a toxin precursor or removes acaricide resistance alleles. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13592-021-00891-5.
Insect Allies – Assessment of a Viral Approach to Plant Genome Editing
20036K. Pfeifer, J. L. Frieß and B. Giese, Integrated Environmental Assessment and Management, 2022-01-12 09:38:06.
The DARPA program Insect Allies has already sparked scientific debate concerning technology assessment-related issues, among which the most prevalent is that of dual use potential. As apart from the issues concerning peaceful applications, the technology also provides the blueprint for a potential bioweapon as further evidenced by a recent publication. However, the combination of a virus-induced genetic modification of crop plants in the field using genetically modified insect vectors poses an increased risk potential in comparison to the hitherto existing use of genetically modified organisms. The technology's high depth of intervention enables a number of sources for hazard and a by trend high exposure, but it is also encumbered with notable deficits in knowledge. These issues call for a thorough technology assessment. This article aims to provide an initial characterization from a technology assessment perspective, focusing on potential sources of risk for this novel invasive environmental biotechnology at an early stage of research and development. This article is protected by copyright. All rights reserved.© 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
Effect of aneuploidy of a nonessential chromosome on gene expression in maize
19950X. Shi, H. Yang, C. Chen, J. Hou, T. Ji, J. Cheng and J. A. Birchler, Plant Journal, 2022-01-07 09:41:30.
The nonessential supernumerary maize B chromosome (B) has recently been shown to contain active genes and be capable of impacting gene expression of the A chromosomes. However, the effect of the B chromosome on gene expression is still unclear. In addition, it is unknown whether the accumulation of the B chromosome would have a cumulative effect on gene expression. To examine these questions, the global expression of genes, microRNAs (miRNAs), and transposable elements (TEs) of leaf tissue of W22 maize (Zea mays) plants with 0 to 7 copies of the B chromosome was studied. All experimental genotypes with B chromosomes displayed a trend of upregulated gene expression for a subset of A-located genes compared to the control. Over three thousand A-located genes are significantly differentially expressed in all experimental genotypes with the B chromosome relative to the control. Modulations of these genes are largely determined by the presence rather than the copy number of the B chromosome. By contrast, the expression of most B-located genes is positively correlated with B copy number, showing a proportional gene dosage effect. The B chromosome also causes increased expression of A-located miRNAs. Differentially expressed miRNAs potentially regulate their targets in a cascade of effects. Furthermore, the varied copy number of the B chromosome leads to the differential expression of A-located and B-located TEs. The findings provide novel insights into the function and properties of the B chromosome.
Stakeholder Views on Engagement, Trust, Performance, and Risk Considerations About Use of Gene Drive Technology in Agricultural Pest Management
19900C. L. Goldsmith, K. E. Kang, E. Heitman, Z. N. Adelman, L. W. Buchman, D. Kerns, X. Liu, R. F. Medina and A. Vedlitz, Health Security, 2021-12-31 08:17:50.
Gene drive is an experimental technique that may make it possible to alter the genetic traits of whole populations of a species through the genetic modification of a relatively small number of individuals. This technology is sufficiently new that literature on the understanding and views of stakeholders and the public regarding the use of gene drive organisms in agricultural pest management is just beginning to emerge. Our team conducted a 2-pronged engagement process with Texas gene drive agricultural stakeholders to ascertain their values, beliefs, and preferences about the efficacy, safety, and risk management considerations of gene drive technology as a potential tool for agricultural pest management. We found that a majority of stakeholders support gene drive research and its potential use for managing agricultural pests. Our work with stakeholders confirms both their willingness to be engaged and the importance they place on stakeholder and public engagement regarding these issues, as well as the need to address these issues before use of gene drive as a pest management mechanism will be accepted and trusted.
Interaction Between Entomology and Gene Technology: Bt-transgenic and Gene Drives for Pests Control .
20105J. C. Ndayıragıje, T. Özek, H. Çevik and İ. Karaca, Türk Bilim ve Mühendislik Dergisi, 3:108-115. 2021-12-22 17:00:56.
Pest control is the major agricultural activity for increasing crop productivity thus insuring food security. Recent pest management programs are depending too much on chemical pesticides, which are a threat to our health and environment. One of the greatest entomological achievements for the benefits of plant protection is the use of Bacillus thuringiensis to produce transgenic plants resisting pests. However, such organisms comprise inconveniences against human health and biodiversity in terms of genetic pollution. In many countries, the use of Genetically Modified Organisms is prohibited. This study review on integration of growing gene technology with actual scientific achievements can help to determine a sustainable solution to the pest’s problem. In this way, many literatures were referred on to comparatively criticize the effectiveness, safety and sustainability of gene drive over Bt transgenic based on scientific soundness. Gene drive technology is a new technic consisting of gene engineering and on-field monitoring of its transgenes. The case in point is the inappropriateness of Bt-transgenes. Practically, gene drive can be an alternative to Bacillus thuringiensis in pest control for increased safety and environmental protection.
Public Perceptions Regarding Genomic Technologies Applied to Breeding Farm Animals: A Qualitative Study
19920F. Z. Naab, D. Coles, E. Goddard and L. J. Frewer, BioTech, 10. 2021-12-03 09:13:38.
The societal acceptability of different applications of genomic technologies to animal production systems will determine whether their innovation trajectories will reach the commercialisation stage. Importantly, technological implementation and commercialisation trajectories, regulation, and policy development need to take account of public priorities and attitudes. More effective co-production practices will ensure the application of genomic technologies to animals aligns with public priorities and are acceptable to society. Consumer rejection of, and limited demand for, animal products developed using novel genomic technologies will determine whether they are integration into the food system. However, little is known about whether genomic technologies that accelerate breeding but do not introduce cross-species genetic changes are more acceptable to consumers than those that do. Five focus groups, held in the north east of England, were used to explore the perceptions of, and attitudes towards, the use of genomic technologies in breeding farm animals for the human food supply chain. Overall, study participants were more positive towards genomic technologies applied to promote animal welfare (e.g., improved disease resistance), environmental sustainability, and human health. Animal “disenhancement” was viewed negatively and increased food production alone was not perceived as a potential benefit. In comparison to gene editing, research participants were most negative about genetic modification and the application of gene drives, independent of the benefits delivered.
The supernumerary B chromosome of maize: drive and genomic conflict
19136J. A. Birchler and H. Yang, Open Biol, 11:210197. 2021-11-04 14:47:43.
The supernumerary B chromosome of maize is dispensable, containing no vital genes, and thus is variable in number and presence in lines of maize. In order to be maintained in populations, it has a drive mechanism consisting of nondisjunction at the pollen mitosis that produces the two sperm cells, and then the sperm with the two B chromosomes has a preference for fertilizing the egg as opposed to the central cell in the process of double fertilization. The sequence of the B chromosome coupled with B chromosomal aberrations has localized features involved with nondisjunction and preferential fertilization, which are present at the centromeric region. The predicted genes from the sequence have paralogues dispersed across all A chromosomes and have widely different divergence times suggesting that they have transposed to the B chromosome over evolutionary time followed by degradation or have been co-opted for the selfish functions of the supernumerary chromosome.
Gene drive: a faster route to plant improvement
18859H. A. Siddiqui, T. Harvey-Samuel and S. Mansoor, Trends in Plant Science, 2021-10-06 18:24:37.
Gene drives for control of vector-borne diseases have been demonstrated in insects but remain challenging in plants. Theoretically, they could be transformative in speeding breeding programs and contributing to food security through providing novel weed control methods. Zhang et al. now report the possibility of implementing gene drive in plants for the first time.
New report demands moratorium on gene drives
18792GM Watch, GM Watch, 2021-09-21 13:49:44.
To help the public understand what's at stake, the Germany-based NGO Save Our Seeds (SOS) has published a report, "Gene Drives: The New Dimension of Genetic Engineering", which can be downloaded as a pdf document. The report provides a scientifically founded overview of how gene drive systems work, their possible areas of application, and the scientific discussion about their risks. It summarises the status of legislation and regulation at the German, European and global levels and recommends urgent political measures. The report explains how gene drives could be used in agriculture – research is focused on controlling pests and weeds and reversing the herbicide resistance in weeds that was caused and exacerbated by the spread of GM herbicide-tolerant crops. Not coincidentally, the report also notes that gene drives could be employed as bioweapons – for example, to eradicate beneficial insects in a region. The report points out, "The US military‘s Defense Advanced Research Projects Agency (DARPA) is one of the largest funders of gene drive research and is financially involved in almost every gene drive research project."
Versatile Applications of the CRISPR/Cas Toolkit in Plant Pathology and Disease Management
19445M. S. Wheatley and Y. N. Yang, Phytopathology, 111:1080-1090. 2021-08-25 21:11:15.
New tools and advanced technologies have played key roles in facilitating basic research in plant pathology and practical approaches for disease management and crop health. Recently. the CRISPR/Cas (clustered regularly interspersed short palindromic repeats/CRISPR-associated) system has emerged as a powerful and versatile tool for genome editing and other molecular applications. This review aims to introduce and highlight the CRISPR/Cas toolkit and its current and future impact on plant pathology and disease management. We will cover the rapidly expanding horizon of various CRISPR/Cas applications in the basic study of plant-pathogen interactions, genome engineering of plant disease resistance, and molecular diagnosis of diverse pathogens. Using the citrus greening disease as an example, various CRISPR/Cas-enabled strategies are presented to precisely edit the host genome for disease resistance, to rapidly detect the pathogen for disease management, and to potentially use gene drive for insect population control. At the cutting edge of nucleic acid manipulation and detection, the CRISPR/Cas toolkit will accelerate plant breeding and reshape crop production and disease management as we face the challenges of 21st century agriculture.
Insect pest management in the age of synthetic biology
18682R. Mateos Fernández, M. Petek, I. Gerasymenko, M. Juteršek, Š. Baebler, K. Kallam, E. Moreno Giménez, J. Gondolf, A. Nordmann, K. Gruden, D. Orzaez and N. J. Patron, Plant Biotechnology Journal, 2021-08-20 13:09:26.
Arthropod crop pests are responsible for 20% of global annual crop losses, a figure predicted to increase in a changing climate where the ranges of numerous species are projected to expand. At the same time, many insect species are beneficial, acting as pollinators and predators of pest species. For thousands of years, humans have used increasingly sophisticated chemical formulations to control insect pests but, as the scale of agriculture expanded to meet the needs of the global population, concerns about the negative impacts of agricultural practices on biodiversity have grown. While biological solutions, such as biological control agents and pheromones, have previously had relatively minor roles in pest management, biotechnology has opened the door to numerous new approaches for controlling insect pests. In this review, we look at how advances in synthetic biology and biotechnology are providing new options for pest control. We discuss emerging technologies for engineering resistant crops and insect populations and examine advances in biomanufacturing that are enabling the production of new products for pest control.
Attack of the Superweeds
18153H. C. Brown, New York Times, 2021-08-18 17:55:25.
If there’s a plant perfectly suited to outcompete the farmers, researchers and chemical companies that collectively define industrial American agriculture, it’s Palmer amaranth. This pigweed (a catchall term that includes some plants in the amaranth family) can re-root itself after being yanked from the ground. It can grow three inches a day. And it has evolved resistance to many of the most common weed killers, continuing to reproduce in what ought to be the worst of circumstances: A three-day-old, herbicide-injured seedling, for example, can expend its last bit of energy to produce seeds before it withers up and dies. Unchecked, Palmer amaranth can suppress soybean yields by nearly 80 percent and corn yields by about 90 percent. Nicolet was ultimately allowed to spray dicamba last summer because he purchased it before restrictions took effect. He used it this year too: The Trump administration issued new approvals for some formulations containing dicamba just a week before the presidential election. Still, Nicolet says the weed killer will eventually stop working on his land, another management tool rendered useless by the pigweed’s remarkable onslaught. Whether that day is 10 years in the future or three, he has no idea, but the Palmer amaranth continues to gain ground all the while. This summer, a handful of pigweeds sprouted in a field that had recently been sprayed. Nicolet couldn’t weed the 96 affected acres by hand, so he decided to let them grow. “It’s not really enough to hurt yield this year,” he said. “But you know, you have 100 weeds out there, the next year you’ll have a million.”
Analysis of the Segregation Distortion of FcRAN1 Genotypes Based on Whole-Genome Resequencing of Fig (Ficus carica L.) Breeding Parents
18171H. Ikegami, K. Shirasawa, H. Yakushiji, S. Yabe, M. Sato, T. Hayashi, K. Tashiro and H. Nogata, Frontiers in Plant Science, 12:8. 2021-08-10 14:56:28.
The common fig (Ficus carica L.) has a gynodioecious breeding system, and its sex phenotype is an important trait for breeding because only female plant fruits are edible. During breeding to select for female plants, we analyzed the FcRAN1 genotype, which is strongly associated with the sex phenotype. In 12 F-1 populations derived from 13 cross combinations, the FcRAN1 genotype segregation ratio was 1:1, whereas the M119226 x H238-107 hybridization resulted in an extremely male-biased segregation ratio (178:7 = male:female). This finding suggests that the segregation distortion was caused by some genetic factor(s). A whole-genome resequencing of breeding parents (paternal and maternal lines) identified 9,061 high-impact SNPs in the parents. A genome-wide linkage analysis exploring the gene(s) responsible for the distortion revealed 194 high-impact SNPs specific to Caprifig6085 (i.e., seed parent ancestor) and 215 high-impact SNPs specific to H238-107 (i.e., pollen parent) in 201 annotated genes. A comparison between the annotated genes and the genes required for normal embryo or gametophyte development and function identified several candidate genes possibly responsible for the segregation distortion. This is the first report describing segregation distortion in F. carica.
Host-associated differentiation of target pests should be assessed before using gene drive as a pest control tool – an opinion
17955R. F. Medina, Entomologia Experimentalis et Applicata, 2021-08-01 12:42:29.
Abstract Advances in gene editing have made feasible the potential use of gene drive for pest control. Ecological risk assessments will certainly be required before this technology can be released into open fields. In this article I argue for the importance to include host-associated differentiation (HAD) as part of ecological risk assessment models due to its potential to modulate gene drive spread and risk. Depending on context, HAD may hamper or facilitate pest control efforts using gene drives. Overlooking HAD may impair pest suppression goals and inflate estimations of effective population sizes whereas its inclusion within gene drive deployment strategies, as a form of ecological containment, may facilitate gene drive implementation under specific scenarios. Because HAD varies geographically and among closely related species, it will need to be assessed on a case-by-case basis. Failure to incorporate HAD within ecological risk assessment models may undermine pest control goals and diminish the accuracy of estimated ecological risks associated with gene drive releases.
Gene drive strategies of pest control in agricultural systems: challenges and opportunities
17836M. Legros, J. M. Marshall, S. Macfadyen, K. R. Hayes, A. Sheppard and L. G. Barrett, Evolutionary Applications, 2021-07-26 14:04:32.
Abstract Recent advances in gene editing technologies have opened new avenues for genetic pest control strategies, in particular around the use of gene drives to suppress or modify pest populations. Significant uncertainty, however, surrounds the applicability of these strategies to novel target species, their efficacy in natural populations, and their eventual safety and acceptability as control methods. In this article we identify issues associated with the potential use of gene drives in agricultural systems, to control pests and diseases that impose a significant cost to agriculture around the world. We first review the need for innovative approaches, and provide an overview of the most relevant biological and ecological traits of agricultural pests that could impact the outcome of gene drive approaches. We then describe the specific challenges associated with using gene drives in agricultural systems, as well as the opportunities that these environments may offer, focusing in particular on the advantages of high-threshold gene drives. Overall we aim to provide a comprehensive view of the potential opportunities and the remaining uncertainties around the use of gene drives in agricultural systems.
Gene Drives – Engineering the Wild
17825L. Sharratt, Sentinel, 2021-07-13 14:52:05.
So far, genetically engineered organisms have been mostly limited to agricultural use, with partial success. Around the world, a few major crops (mostly corn, soy, and cotton) are genetically engineered, predominantly for herbicide tolerance and insect resistance. However, the newer techniques of genome editing (also called gene editing) mean that a much wider variety of organisms can now be genetically engineered, including for many purposes outside of food and farming. This increased power is most dramatically illustrated in the development of gene drive technology. Unlike genetically engineered plants and animals intended for confined use in agricultural production, gene drive organisms are expressly designed for intentional, long-lived release into the wild. Gene drives are a technology through which a few individual genetically engineered organisms would be deployed to intentionally push new genes through an entire population of a species in the wild or in a farm ecosystem. Through the gene drive mechanism, new genes would be inherited by all offspring in subsequent generations, not just the expected half in normal inheritance. When gene drive organisms reproduce, specific traits as well as the gene drive mechanism itself would be passed on. Making such spreading genetic changes to an organism, or eliminating it in the wild, could disrupt whole ecosystems in ways that are difficult or impossible to predict or reverse.
UC San Diego scientists develop the first CRISPR/Cas9-based gene drive in plants
17563M. Aguilera, UC San Diego News Center, 2021-06-25 14:55:55.
With a goal of breeding resilient crops that are better able to withstand drought and disease, University of California San Diego scientists have developed the first CRISPR-Cas9-based gene drive in plants. While gene drive technology has been developed in insects to help stop the spread of vector-borne diseases such as malaria, researchers in Professor Yunde Zhao's lab, along with colleagues at the Salk Institute for Biological Studies, demonstrated the successful design of a CRISPR-Cas9-based gene drive that cuts and copies genetic elements in Arabidopsis plants. Breaking from the traditional inheritance rules that dictate that offspring acquire genetic materials equally from each parent (Mendelian genetics), the new research uses CRISPR-Cas9 editing to transmit specific, targeted traits from a single parent in subsequent generations. Such genetic engineering could be used in agriculture to help plants defend against diseases to grow more productive crops. The technology also could help fortify plants against the impacts of climate change such as increased drought conditions in a warming world.
Selective inheritance of target genes from only one parent of sexually reproduced F1 progeny in Arabidopsis
17567T. Zhang, M. Mudgett, R. Rambabu, B. Abramson, X. Dai, T. P. Michael and Y. Zhao, Nature Communications, 12:3854. 2021-06-22 15:05:16.
Sexual reproduction constrains progeny to inherit allelic genes from both parents. Selective acquisition of target genes from only one parent in the F1 generation of plants has many potential applications including the elimination of undesired alleles and acceleration of trait stacking. CRISPR/Cas9-based gene drives can generate biased transmission of a preferred allele and convert heterozygotes to homozygotes in insects and mice, but similar strategies have not been implementable in plants because of a lack of efficient homology-directed repair (HDR). Here, we place a gene drive, which consists of cassettes that produce Cas9, guide RNAs (gRNA), and fluorescent markers, into the CRYPTOCHROME 1 (CRY1) gene through CRISPR/Cas9-mediated HDR, resulting in cry1drive lines. After crossing the cry1drive/cry1drive lines to wild type, we observe F1 plants which have DNA at the CRY1 locus from only the cry1drive/cry1drive parent. Moreover, a non-autonomous trans-acting gene drive, in which the gene drive unit and the target gene are located on different chromosomes, converts a heterozygous mutation in the target gene to homozygous. Our results demonstrate that homozygous F1 plants can be obtained through zygotic conversion using a CRISPR/Cas9-based gene drive.
Sequence of the supernumerary B chromosome of maize provides insight into its drive mechanism and evolution
17202N. Blavet, H. Yang, H. Su, P. Solanský, R. N. Douglas, M. Karafiátová, L. Šimková, J. Zhang, Y. Liu, J. Hou, X. Shi, C. Chen, M. El-Walid, M. E. McCaw, P. S. Albert, Z. Gao, C. Zhao, G. Ben-Zvi, L. Glick, G. Kol, J. Shi, J. Vrána, H. Šimková, J. C. Lamb,, Proceedings of the National Academy of Sciences, 118:e2104254118. 2021-06-05 15:32:03.
B chromosomes are nonvital chromosomes found in thousands of plants and animals that persist through various drive mechanisms. The drive mechanism of the maize B chromosome consists of mitotic nondisjunction at the second pollen division to produce two unequal sperm and then the sperm with the B chromosomes preferentially fertilizes the egg in double fertilization. A high-quality sequence of the maize B chromosome together with genetic analysis reveals the cis factor for nondisjunction is a B chromosome-specific repeat interspersed in and around the centromere. The gene and transposable element content of the B chromosome and relaxed purifying selection of transposed protein-encoding genes suggest that the chromosome has been present in the evolutionary lineage for millions of years.B chromosomes are enigmatic elements in thousands of plant and animal genomes that persist in populations despite being nonessential. They circumvent the laws of Mendelian inheritance but the molecular mechanisms underlying this behavior remain unknown. Here we present the sequence, annotation, and analysis of the maize B chromosome providing insight into its drive mechanism. The sequence assembly reveals detailed locations of the elements involved with the cis and trans functions of its drive mechanism, consisting of nondisjunction at the second pollen mitosis and preferential fertilization of the egg by the B-containing sperm. We identified 758 protein-coding genes in 125.9 Mb of B chromosome sequence, of which at least 88 are expressed. Our results demonstrate that transposable elements in the B chromosome are shared with the standard A chromosome set but multiple lines of evidence fail to detect a syntenic genic region in the A chromosomes, suggesting a distant origin. The current gene content is a result of continuous transfer from the A chromosomal complement over an extended evolutionary time with subsequent degradation but with selection for maintenance of this nonvital chromosome.Raw data used for sequence assembly of B73 line possessing B chromosome(s) and additional RNA-seq data used for B chromosome annotation are available in NCBI-SRA as BioProject PRJNA633287. Sequence reads for B-deficiency-carrying lines of maize are available in NCBI-SRA as BioProject PRJNA634743. Input-seq data are available in NCBI-GEO under accession GSE152074. The final B chromosome sequence and its annotation are available at MaizeGDB (https://www.maizegdb.org/) under the name Zm-B73_B-CHROMOSOME-MBSC-1.0 with the identifier Zm00044a.
Researchers report reference genome for maize B chromosome
17172Chinese Academy of Sciences, Phys Org, 2021-05-31 19:46:00.
Three groups recently reported a reference sequence for the supernumerary B chromosome in maize in a study published online in PNAS. Dr. James Birchler's group from University of Missouri, Dr. Jan Barto's group from Institute of Experimental Botany of the Czech Academy of Sciences and Dr. Han Fangpu's group from the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences worked collaboratively on the study. Supernumerary B chromosomes persist in thousands of plant and animal genomes despite being nonessential. They are maintained in populations by mechanisms of "drive" that make them inherited at higher than typical Mendelian rates. Key properties such as its origin, evolution, and the molecular mechanism for its accumulation in maize have remained unclear even though such chromosomes have been a potent tool for studying maize genetics.
Ethics of Genome Editing
16622European Group on Ethics, European Group on Ethics in Science and New Technologies, 2021-03-19 18:16:09.
This Opinion addresses the profound ethical questions raised and revived by them. It analyses various domains of application, from human health to animal experimentation, from livestock breeding to crop variety and to gene drives. With its wide view across areas, it identifies underlying and overarching issues that deserve our concerted attention, among them, the different meanings that ought to be attributed to humanness, naturalness or diversity. This enables conclusions that provide panoramic perspectives complementing narrower, area-specific analyses. In the same vein, the Opinion is concerned with the global dimension of genome editing and its regulation and formulates recommendations with a particular focus on the international level.
Holocentric Chromosomes Probably Do Not Prevent Centromere Drive in Cyperaceae
16676M. Kratka, J. Smerda, K. Lojdova, P. Bures and F. Zedek, Frontiers in Plant Science, 12:9. 2021-02-19 14:30:42.
In response to these selfish centromeres, the histone protein CenH3, which recruits kinetochore components, adaptively evolves to restore chromosomal parity and counter the detrimental effects of centromere drive. Holocentric chromosomes, whose kinetochores are assembled along entire chromosomes, have been hypothesized to prevent expanded centromeres from acquiring a selective advantage and initiating centromere drive. In such a case, CenH3 would be subjected to less frequent or no adaptive evolution. Using codon substitution models, we analyzed 36 CenH3 sequences from 35 species of the holocentric family Cyperaceae. We found 10 positively selected codons in the CenH3 gene [six codons in the N-terminus and four in the histone fold domain (HFD)] and six branches of its phylogeny along which the positive selection occurred. One of the positively selected codons was found in the centromere targeting domain (CATD) that directly interacts with DNA and its mutations may be important in centromere drive suppression. The frequency of these positive selection events was comparable to the frequency of positive selection in monocentric clades with asymmetric female meiosis. Taken together, these results suggest that preventing centromere drive is not the primary adaptive role of holocentric chromosomes, and their ability to suppress it likely depends on their kinetochore structure in meiosis.
Combining refuges with transgenic insect releases for the management of an insect pest with non-recessive resistance to Bt crops in agricultural landscapes
17006T. R. Brewer and M. B. Bonsall, Journal of Theoretical Biology, 509:11. 2021-01-21 12:35:03.
Reinforcing the high-dose/refuge strategy with releases of transgenic insects has been suggested as a method for simultaneously managing agricultural pest populations and resistance to transgenic crops. Theoretical and empirical studies have shown that these approaches can work when deployed against closed populations and the assumptions of the HDR strategy are met. However, field-evolved resistance is often linked to non-recessive resistance or refuge non-compliance, and pest management regimes are likely to take place at the landscape-level. It is therefore important to understand how effective such strategies are when resistance is non-recessive, and how they could be employed in agricultural landscapes. We developed a spatially-explicit model to investigate the efficacy of strategies combining refuges with transgenic insect releases to manage a pest with non-recessive resistance in agricultural landscapes. We compared two release strategies, area-wide releases and localised releases targeted at population hotspots, and analysed the effects of refuge and release parameters on population and resistance dynamics. Area-wide releases reliably achieved landscape-level pest eradication. Localised releases also eradicated the pest when low release thresholds were combined with high release ratios, and maintained the pest at low densities when insufficient to achieve extinction. Reinforcing refuges with localised releases also greatly enhanced the probability of resistance extinction. However, when resistance remained in the population, localised releases prevented resistance from reaching fixation rather than greatly delaying or reversing resistance evolution. Our work indicates that combining refuges with simple release policies is effective for landscape-level pest suppression when the HDR assumptions are violated, but more nuanced release strategies may be required to enhance the benefits to resistance management. (C) 2020 Elsevier Ltd. All rights reserved.
Next-generation tools to control biting midge populations and reduce pathogen transmission
15940P. Shults, L. W. Cohnstaedt, Z. N. Adelman and C. Brelsfoard, Parasites and Vectors, 14:31. 2021-01-07 14:52:23.
Biting midges of the genus Culicoides transmit disease-causing agents resulting in a significant economic impact on livestock industries in many parts of the world. Localized control efforts, such as removal of larval habitat or pesticide application, can be logistically difficult, expensive and ineffective if not instituted and maintained properly. With these limitations, a population-level approach to the management of Culicoides midges should be investigated as a means to replace or supplement existing control strategies. Next-generation control methods such as Wolbachia- and genetic-based population suppression and replacement are being investigated in several vector species. Here we assess the feasibility and applicability of these approaches for use against biting midges. We also discuss the technical and logistical hurdles needing to be addressed for each method to be successful, as well as emphasize the importance of addressing community engagement and involving stakeholders in the investigation and development of these approaches.
Expert advises farmers to adopt gene drive-based pest control technology
15029S. Thompson, naija247news, 2020-11-09 15:36:25.
Dr Rose Gidado, County Coordinator, Open Forum on Agricultural Biotechnology(OFAB), has advised farmers to adopt the gene drive-based pest control technology. Gidado, also Deputy Director, National Biotechnology Development Agency (NABDA), said the adoption would significantly help to restore Nigeria’s food crop industry. According to her, Nigerian agricultural system is dominated by the application of synthetic pesticides which have resulted in environmental pollution. Gidado said that it had contributed greatly to climate change, with lethal consequences like increased pest attack, decreased crop yield and extreme heat stress in plants. The scientist said the application of gene drive in Nigeria’s agricultural system, would help greatly in the control of deadly insect pests which cause damages to crops and reduction in food production.
Teach Me in 10 – Gene Drive Research with Dr. Jennifer Baltzegar
14362J. Baltzegar, Technology Networks, 2020-09-10 15:44:16.
Dr Baltzegar teaches us about how the maturation of genetic engineering approaches has advanced gene drives, the two different strategies for gene drives and some of the key questions surrounding the application of gene drives in society.
Atypical meiosis can be adaptive in outcrossed Schizosaccharomyces pombe due to wtf meiotic drivers
13899M. A. Bravo Núñez, I. M. Sabbarini, L. E. Eide, R. L. Unckless and S. E. Zanders, eLife, 9:e57936. 2020-08-13 13:30:44.
Here, we demonstrate that in scenarios analogous to outcrossing, wtf drivers generate a fitness landscape in which atypical spores, such as aneuploids and diploids, are advantageous. In this context, wtf drivers can decrease the fitness costs of mutations that disrupt meiotic fidelity and, in some circumstances, can even make such mutations beneficial. This work empirically demonstrates the potential for meiotic drivers to shape the evolution of gametogenesis.
Après les OGM, la nouvelle technique du forçage génétique inquiète écologistes et scientifiques
13595H. Leussier, Reporterre, 2020-07-28 13:04:33.
Les organismes issus du forçage génétique peuvent transmettre, sans autre intervention humaine, des gènes modifiés à tous leurs descendants. Cette technique permettrait d’éradiquer des espèces nuisibles, comme certains moustiques vecteurs de la malaria. Mais des associations, des scientifiques et des responsables politiques, inquiets de potentiels effets dévastateurs, réclament un moratoire international.
The future of beef might be a sausage fest
13479N. Johnson, grist, 2020-07-24 21:00:33.
N. Johnson. (2020) grist. A media report on the creation of a cow with a sex ratio altering genetic change expected to lead to 3/4 of the cow's offspring being males. This type of sex ratio distortion results in gene drive and is also being considered to help control populations of invasive mammals.
Meet Cosmo the Frankenbull: Scientists genetically engineer a bull calf so that 75 per cent of its offspring will be male
13476J. Pinkstone, Daily Mail, 2020-07-24 20:58:14.
J. Pinkstone (2020). Daily Mail. A media report on the creation of a cow with a sex ratio altering genetic change expected to lead to 3/4 of the cow's offspring being males. This type of sex ratio distortion results in gene drive and is also being considered to help control populations of invasive mammals.
A Crispr calf is born. It’s definitely a boy
13454M. Molteni, WIRED, 2020-07-24 16:25:14.
M. Molteni (2020). Wired. UC Davis scientists spent years editing a sex-determining gene into bovine embryos. In April, Cosmo arrived—and his DNA reveals how far the field has to go. This type of sex ratio distortion results in gene drive and is also being considered to help control populations of invasive mammals.
Meet the first genetically modified bull. Why did scientists change it
13473J. Kessler, Free News, 2020-07-23 20:52:51.
J. Kessler (2020). Free News. UC Davis scientists have successfully introduced a bovine embryo, or the bovine SRY gene, which is responsible for the development of the male. This is the first demonstration of targeted gene insertion for large DNA sequences through embryo-mediated genome editing in cattle. This type of sex ratio distortion results in gene drive and is also being considered to help control populations of invasive mammals.
Scientists use CRISPR technology to insert sex-determining gene
13452A. Quinton, Phys Org, 2020-07-23 16:21:10.
A. Quinton (2020). Phys Org. Scientists at the University of California, Davis, have successfully produced a bull calf, named Cosmo, who was genome-edited as an embryo so that he'll produce more male offspring. The research was presented in a poster on July 23 at the American Society of Animal Science meeting. This type of sex ratio distortion results in gene drive and is also being considered to help control populations of invasive mammals.
An argument for gene drive technology to genetically control populations of insects like mosquitoes and locusts
13196I. Ronai and B. Lovett, The Conversation, 2020-07-14 18:15:19.
The fate of society rests in part on how humans navigate their complicated relationship with insects – trying to save “good” insects and control “bad” ones. Some insects, like mosquitoes, bite people and make them sick – remember Zika? Now the U.S. mosquito season is already in full swing, with over 10 cases of Dengue fever reported in the Florida Keys this year. Some insects, like bees, are pollinators that help produce our food. Others, like locusts, currently threaten crops in East Africa and Asia, preferring to eat our food instead. Insects have proven themselves extremely capable at evolving strategies to get around control methods, such as chemical insecticides and habitat modification, and current pest control technologies are simply not keeping up.
Gene Drive: Can this be the Future of Agricultural Pest Management?
13156P. Mondal, U. Mohapatra and M. Ganguly, International Journal of Current Microbiology and Applied Sciences, 9. 2020-06-10 14:25:16.
A world free of hunger may be possible when the agricultural production exceeds the global demand for the food. In the era of increasing population, the need for increased food production can be attainable by managing the destructive pests of the agricultural and horticultural crops. The detrimental effects of the pesticides and the attitudes of society towards transgenic crops indicate the researchers to catch out Gene Drive as the substitute method for former methods of crop pest management. In this context, the present narration describes how the self-sustaining CRISPR-based gene drive technology will be the leading technique in the near future for agriculture pest management.
Bioengineering horizon scan 2020
12449L. Kemp, L. Adam, C. R. Boehm, R. Breitling, R. Casagrande, M. Dando, A. Djikeng, N. G. Evans, R. Hammond, K. Hills, L. A. Holt, T. Kuiken, A. Markotić, P. Millett, J. A. Napier, C. Nelson, S. S. ÓhÉigeartaigh, A. Osbourn, M. J. Palmer, N. J. Patron, E. P, eLife, 9:e54489. 2020-05-29 20:28:54.
Horizon scanning is intended to identify the opportunities and threats associated with technological, regulatory and social change. In 2017 some of the present authors conducted a horizon scan for bioengineering (Wintle et al., 2017). Here we report the results of a new horizon scan that is based on inputs from a larger and more international group of 38 participants. The final list of 20 issues includes topics spanning from the political (the regulation of genomic data, increased philanthropic funding and malicious uses of neurochemicals) to the environmental (crops for changing climates and agricultural gene drives). The early identification of such issues is relevant to researchers, policy-makers and the wider public.
Le forçage génétique (gène drive) et ses applications
18210V. Courtier-Orgogozo, Bulletin de l'Académie Vétérinaire de France, 172:94-98. 2020-05-18 15:11:30.
Gene drive is a new genetic engineering technology that has been developed over the past five years and that allows genetic modifications to spread rapidly in natural populations. Potential applications are numerous, for public health issues, agriculture and conservation biology. This article presents the current developments in this biotechnology, as well as the issues and risks associated with it.
Case Study 2: Oilseed Rape (Brassica napus L.)
11257Johnannes L. Frieß, Broder Breckling, Kathrin Pascher and Windfried Schröder, Gene Drives at Tipping Points, 2020-04-28 18:36:22.
SPAGESelf-Propagating Artificial Genetic Elements (SPAGE) (Self-Propagating Artificial Genetic Element) technologies allow for a proliferation of genetic information on the populationPopulation level at a higher rate than usual Mendelian inheritanceMendelian inheritance. Currently projected developments of SPAGESelf-Propagating Artificial Genetic Elements (SPAGE) mainly aim at a reduction or suppressionSuppression of animal populationsPopulation which are considered to be harmful or undesirable (Oye et al. 2014). However, the application of SPAGESelf-Propagating Artificial Genetic Elements (SPAGE) is not limited to animals only. In principle, also plant populationsPopulation can be targeted (National Academies of Sciences 2016). The GeneTip case study on oilseed rape (Brassica napus) is intended to assess, which interactions play a role in a plant-specific context to address relevant ecological interactions that need to be fully explored in order to estimate potential risksRisk.
Understanding the Science of Gene Drive and the Potential for an Improved Crop Pest Control System in Nigeria
14882A. Isah and R. S. M. Gidado, OFAB Nigeria, 2020-02-26 15:52:39.
Several studies have shown that the Cas9-mediated gene drive technology is cheaper and will be easily affordable by the efficient Nigerian scientists to explore. The application of the gene drive technologies have many more controls over several other devastating insects in Nigeria and may be very necessary to adopt it to rescue our ailing food crop industry from the attack by destructive insect pest of crops.
Gene technologies in weed management: a technical feasibility analysis
7948N. Kumaran, A. Choudhary, M. Legros, A. W. Sheppard, L. G. Barrett, D. M. Gardiner and S. Raghu, Current Opinion in Insect Science, 38:6-14. 2020-01-30 20:44:15.
With the advent of new genetic technologies such as gene silencing and gene drive, efforts to develop additional management tools for weed management is gaining significant momentum. These technologies promise novel ways to develop sustainable weed control options because gene silencing can switch-off genes mediating adaptation (e.g. growth, herbicide resistance), and gene drive can be used to spread modified traits and to engineer wild populations with reduced fitness. However, applying gene silencing and/or gene drive is expected to be inherently complex as their application is constrained by several methodological and technological difficulties. In this review we explore the challenges of these technologies, and discuss strategies and resources accessible to accelerate the development of gene-tech based tools for weed management. We also highlight how gene technologies can be integrated into existing management tactics such as classical biological control, and their possible interactions.
Gene drives in Wisconsin agriculture: What are they, and should you support it?
6026Jones, M. and Mitchell, P. D., Renk Agribusiness Institute, 2019-10-02 20:34:10.
Spotted wing drosophila and citrus psyllid are not serious economic problems for Wisconsin agriculture. However, these and other smaller, geographically limited applications of gene drives are excellent ways to prove the concept and refine the methods. Pending the outcome of these limited-scale applications, we are likely to eventually see implications for row crop agriculture such as the management of serious and widespread pests such like corn rootworm, European corn borer, soybean aphid and Colorado potato beetle. Applications which could provide tremendous benefits to Wisconsin producers.
A 2017 horizon scan of emerging issues for global conservation and biological diversity
4067Sutherland, WJB, P.; Broad, S.; Clout, M.; Connor, B.; Cote, I. M.; Dicks, L. V.; Doran, H.; Entwistle, A. C.; Fleishman, E.; Fox, M.; Gaston, K. J.; Gibbons, D. W.; Jiang, Z.; Keim, B.; Lickorish, F. A.; Markillie, P.; Monk, K. A.; Pearce-Higgins, J. W.; Peck, L. S.; Pretty, J.; Spalding, M. D.; Tonneijck, F. H.; Wintle, B. C.; Ockendon, N., Trends in Ecology & Evolution, 32:31-40. 2019-09-09 00:00:00.
We present the results of our eighth annual horizon scan of emerging issues likely to affect global biological diversity, the environment, and conservation efforts in the future. The potential effects of these novel issues might not yet be fully recognized or understood by the global conservation community, and the issues can be regarded as both opportunities and risks. A diverse international team with collective expertise in horizon scanning, science communication, and conservation research, practice, and policy reviewed 100 potential issues and identified 15 that qualified as emerging, with potential substantial global effects. These issues include new developments in energy storage and fuel production, sand extraction, potential solutions to combat coral bleaching and invasive marine species, and blockchain technology.
Herbicide resistant weeds: A call to integrate conventional agricultural practices, molecular biology knowledge and new technologies
6040V. E. Perotti, A. S. Larran, V. E. Palmieri, A. K. Martinatto and H. R. Permingeat, Plant Science, 290:110255. 2019-09-06 21:01:14.
Herbicide resistant (HR) weeds are of major concern in modern agriculture. This situation is exacerbated by the massive adoption of herbicide-based technologies along with the overuse of a few active ingredients to control weeds over vast areas year after year. Also, many other anthropological, biological, and environmental factors have defined a higher rate of herbicide resistance evolution in numerous weed species around the world. This review focuses on two central points: 1) how these factors have affected the resistance evolution process; and 2) which cultural practices and new approaches would help to achieve an effective integrated weed management. We claim that global climate change is an unnoticed factor that may be acting on the selection of HR weeds, especially those evolving into non-target-site resistance mechanisms. And we present several new tools –such as Gene Drive and RNAi technologies- that may be adopted to cope with herbicide resistance spread, as well as discuss their potential application at field level. This is the first review that integrates agronomic and molecular knowledge of herbicide resistance. It covers not only the genetic basis of the most relevant resistance mechanisms but also the strengths and weaknesses of traditional and forthcoming agricultural practices.
B chromosome first—mechanisms behind the drive of B chromosomes uncovered
17167Leibniz Institute of Plant Genetics and Crop Plant Research, Phy Org, 2019-06-04 19:27:50.
The specific number of chromosomes is one of the defining characteristics of a species. Whilst the common fruit fly carries 8 chromosomes, the genome of bread wheat counts 42 chromosomes. In comparison, the human genome is made out of a total of 46 chromosomes. However, about 15% of all eukaryotic species additionally carry supernumerary chromosomes referred to as "B chromosomes". Other than the essential chromosomes of the genome, B chromosomes are expendable and often preferentially inherited. This leads to a transmission advantage for B chromosomes called "chromosome drive". To date, little knowledge exists about the mechanisms behind this phenomenon. Researchers from the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) in Gatersleben have now been able to decipher the mechanisms behind the drive of B chromosomes in the goatgrass Aegilops speltoides. The novel insights in the workings of chromosome drive were recently published in New Phytologist.
A natural, conditional gene drive in plants
3903Conner, AJJ, J.M.E., bioRxiv, 519884:1-10. 2019-01-21 00:00:00.
A new class of gene drive in plant populations with herbicide resistance is described; a conditional gene drive that operates following herbicide application. Screening progeny from controlled crosses of Brassica napus heterozygous for a dominant allele conferring chlorsulfuron resistance, demonstrated that the herbicide imposes in planta gametic selection against pollen and ovules with the recessive allele for herbicide susceptibility, as well as embryonic selection against embryos homozygous for the susceptible allele. We postulate that natural gene drives are common in plant populations and can operate in a conditional manner resulting in non-Mendelian inheritance in response to abiotic and biotic stresses.
Transmission ratio distortion is frequent in Arabidopsis thaliana controlled crosses
3942Seymour, DKC, E.; Arioz, B. I.; Koenig, D.; Weigel, D., Heredity, 122:294-304. 2019-01-20 00:00:00.
The equal probability of transmission of alleles from either parent during sexual reproduction is a central tenet of genetics and evolutionary biology. Yet, there are many cases where this rule is violated. The preferential transmission of alleles or genotypes is termed transmission ratio distortion (TRD). Examples of TRD have been identified in many species, implying that they are universal, but the resolution of species-wide studies of TRD are limited. We have performed a species-wide screen for TRD in over 500 segregating F-2 populations of Arabidopsis thaliana using pooled reduced-representation genome sequencing. TRD was evident in up to a quarter of surveyed populations. Most populations exhibited distortion at only one genomic region, with some regions being repeatedly affected in multiple populations. Our results begin to elucidate the species-level architecture of biased transmission of genetic material in A. thaliana, and serve as a springboard for future studies into the biological basis of TRD in this species.
Making a murderer: The evolutionary framing of hybrid gamete-killers
3949Sweigart, ALB, Yaniv; Fishman, Lila, Trends in Genetics, 35:245-252. 2019-01-07 00:00:00.
Recent molecular investigations of hybrid incompatibilities have revealed fascinating patterns of genetic interactions that have been interpreted as the remnants of a history of selfish evolution. Instead of framing hybrid incompatibilities in light of genetic conflict, we advocate assuming their innocence. Researchers must build a strong theory for each case, supported by population genetic evidence, such that the role of conflict in the evolution of a hybrid incompatibility can be proven beyond reasonable doubt. This will require careful investigation of the evolutionary history of these incompatibilities, a reckoning of how the reproductive biology of study organisms impacts on the likelihood of genetic conflict, and molecular evidence of the rapid selfish spread of these alleles.
Gene drives in plants: opportunities and challenges for weed control and engineered resilience
3887Barrett, LGL, Mathieu; Kumaran, Nagalingam; Glassop, Donna; Raghu, S.; Gardiner, Donald M., Proceedings of the Royal Society B: Biological Sciences, 286:9. 2019-01-05 00:00:00.
Plant species, populations and communities are under threat from climate change, invasive pathogens, weeds and habitat fragmentation. Despite considerable research effort invested in genome engineering for crop improvement, the development of genetic tools for the management of wild plant populations has rarely been given detailed consideration. Gene drive systems that allow direct genetic management of plant populations via the spread of fitness-altering genetic modifications could be of great utility. However, despite the rapid development of synthetic tools and their enormous promise, little explicit consideration has been given to their application in plants and, to date, they remain untested. This article considers the potential utility of gene drives for the management of wild plant populations, and examines the factors that might influence the design, spread and efficacy of synthetic drives. To gain insight into optimal ways to design and deploy synthetic drive systems, we investigate the diversity of mechanisms underlying natural gene drives and their dynamics within plant populations and species. We also review potential approaches for engineering gene drives and discuss their potential application to plant genomes. We highlight the importance of considering the impact of plant life-history and genetic architecture on the dynamics of drive, investigate the potential for different types of resistance evolution, and touch on the ethical, regulatory and social challenges ahead.
Gene driving the farm: who decides, who owns, and who benefits?
3907Montenegro de Wit, M, Agroecology and Sustainable Food Systems, 43:1054-1074. 2019-01-05 00:00:00.
This commentary essay explores the social and ecological implications of gene-driving agriculture.
Just Say No to Agricultural Gene Drives
4722Bassey-Orovwuje, M., Project Syndicate, 2018-10-16 00:00:00.
By forcing laboratory-made genes on an entire population or species, cutting-edge gene-drive technologies have the power to transform entire ecosystems in one fell swoop. But where leading industrial agriculture firms see dollar signs, farmers in the regions where gene drives could be unleashed see a mortal threat to their livelihoods.
Forcing the Farm
4558etc group, etc group, 2018-10-10 00:00:00.
This report is being issued as an alert to governments, civil society organisations and grassroots movements. It points to how gene drives, while promoted as a tool for medicine and conservation, will find their real use in food and farming by agribusiness. It calls for a pause in applied research in gene drives and a halt on releases to the environment until a thorough and public process of dialogue has taken place and rules are established that ensure clear consent and defence of food sovereignty
Genetics-based methods for agricultural insect pest management
18687N. Alphey and M. B. Bonsall, Agricultural and Forest Entomology, 20:131-140. 2018-05-01 13:30:37.
Abstract The sterile insect technique is an area-wide pest control method that reduces agricultural pest populations by releasing mass-reared sterile insects, which then compete for mates with wild insects. Contemporary genetics-based technologies use insects that are homozygous for a repressible dominant lethal genetic construct rather than being sterilized by irradiation. Engineered strains of agricultural pest species, including moths such as the diamondback moth Plutella xylostella and fruit flies such as the Mediterranean fruit fly Ceratitis capitata, have been developed with lethality that only operates on females. Transgenic crops expressing insecticidal toxins are widely used; the economic benefits of these crops would be lost if toxin resistance spread through the pest population. The primary resistance management method is a high-dose/refuge strategy, requiring toxin-free crops as refuges near the insecticidal crops, as well as toxin doses sufficiently high to kill wild-type insects and insects heterozygous for a resistance allele. Mass-release of toxin-sensitive engineered males (carrying female-lethal genes), as well as suppressing populations, could substantially delay or reverse the spread of resistance. These transgenic insect technologies could form an effective resistance management strategy. We outline some policy considerations for taking genetic insect control systems through to field implementation.
Gene Drives – Wundermittel? Biowaffe?
12380Swiss Academy of Sciences, 2018-02-19 21:02:40.
Gene drives are genetic elements that skew the pattern of inheritance of a given characteristic in sexually reproduc- ing organisms. They can be used to spread a characteristic that can alter or even reduce the numbers of individuals in wild populations of a certain species.
Gene drives and the management of agricultural pests
13810R. F. Medina, Journal of Responsible Innovation, 5:S255-S262. 2018-01-24 16:01:13.
Like all pest control strategies, gene drives are not hazard-free. Ecological risk assessment of gene drives designed to control agricultural pests should be conducted before their deployment. The present commentary provides some thoughts on some of the issues one should consider when contemplating using gene drives in the management of agricultural pests.
Summary
13808Committee on Gene Drive Research in Non-Human Organisms: Recommendations for Responsible, Journal of Responsible Innovation, 5:S243-S254. 2018-01-24 15:58:19.
Scientists have studied gene drives for more than 50 years. The development of a powerful genome editing tool in 2012, CRISPR/Cas9,1 led to recent breakthroughs in gene drive research that built on that half century’s worth of knowledge, and stimulated new discussion of the potential applications and implications of gene drive technologies.
Agricultural production: assessment of the potential use of Cas9-mediated gene drive systems for agricultural pest control
13796M. J. Scott, F. Gould, M. Lorenzen, N. Grubbs, O. Edwards and D. O’Brochta, Journal of Responsible Innovation, 5:S98-S120. 2018-01-24 15:43:20.
To highlight how gene drives could be useful for control of agricultural insect pests, we selected species that are pests of animals (New World screwworm), plants (spotted wing Drosophila, diamondback moth, Bemisia tabaci whitefly), or stored grains (red flour beetle). We provide examples of gene drives that target specific genes including female-essential genes. Further, we discuss issues related to containment in the laboratory and eventual field testing of strains harboring a Cas9-mediated gene drive system.
Gene drive systems: Do they have a place in agricultural weed management?
4000Neve, P, Pest Management Science, 74:2672-2679. 2018-01-18 00:00:00.
There is a pressing need for novel control techniques in agricultural weed management. Direct genetic control of agricultural pests encompasses a range of techniques to introduce and spread novel, fitness-reducing genetic modifications through pest populations. Recently, the development of CRISPR-Cas9 gene editing has brought these approaches into sharper focus. Proof of concept for CRISPR-Cas9 based gene drives has been demonstrated for control of disease-vectoring insects. This article considers whether and how gene drives may be applied in agricultural weed management, focusing on CRISPR-Cas9 based systems. Population suppression drives might be employed to introduce and proliferate deleterious mutations that directly impact fitness and weediness, whereas population sensitizing drives would seek to edit weed genomes so that populations are rendered more sensitive to subsequent management interventions. Technical challenges relating to plant transformation and gene editing in planta are considered, and the implementation of gene drives for timely and sustainable weed management is reviewed in the light of weed population biology. The technical, biological, practical and regulatory challenges remain significant. Modelling-based studies can inform how and if gene drives could be employed in weed populations. These studies are an essential first step towards determining the utility of gene drives for weed management. This article is protected by copyright. All rights reserved.
Identifying and detecting potentially adverse ecological outcomes associated with the release of gene-drive modified organisms
3980Hayes, KRH, G. R.; Dana, G. V.; Foster, S. D.; Ford, J. H.; Thresher, R.; Ickowicz, A.; Peel, D.; Tizard, M.; De Barro, P.; Strive, T.; Dambacher, J. M., Journal of Responsible Innovation, 5:S139-S158. 2018-01-18 00:00:00.
Synthetic gene drives could provide new solutions to a range of old problems such as controlling vector-borne diseases, agricultural pests and invasive species. In this paper, we outline methods to identify hazards and detect potentially adverse ecological outcomes at the individual (genotype, phenotype), population, community and ecosystem level, when progressing Gene Drive Modified Organisms through a phased test and release pathway. We discuss the strengths and weaknesses of checklists and structured hazard analysis techniques, identify methods to help meet some of the challenges of detecting adverse ecological outcomes in experiments and confined field trials, and discuss ways to improve the efficiency and statistical rigour of post-release monitoring strategies.
THE NATIONAL BIOSAFETY TECHNICAL COMMISSION (CTNBio) NORMATIVE RESOLUTION No. 16, OF JANUARY 15, 2018
16083CTNBio, National Biosafety Technical Commission of Brasil, 2018-01-15 15:17:02.
Sets forth the technical requirements for submitting an inquiry to the CTNBio concerning Precision Breeding Innovation Techniques. THE NATIONAL BIOSAFETY TECHNICAL COMMISSION (CTNBio), using its legal and regulatory powers and in observance of sections XV and XVI of article 14 of Law No. 11.105 of March 24, 2005; Whereas there is a need to assess Precision Breeding Innovation (PBI) techniques, which also comprise the so-called New Breeding Technologies (NBTs) in the light of Law No. 11.105 of March 24, 2005;
Economic issues to consider for gene drives
3997Mitchell, PDB, Z.; McRoberts, N., Journal of Responsible Innovation, 5:S180-S202. 2018-01-15 00:00:00.
We examine four economic issues regarding gene drive applications made possible by gene editing technologies. First, whether gene drives are self-sustaining or self-limiting will largely determine which types of organizations have incentives to develop and deploy gene drives and greatly influence their governance and regulation. Social factors will also play key roles, particularly public perceptions, with these perceptions co-determined with regulation and governance. Second, gene drive applications will generate unintended negative social impacts that will partially offset benefits. Third, economic surplus, the traditional measure of economic benefits, incompletely captures the welfare impacts of gene drive applications. Fourth, gene drives imply dynamic nonlinearities that make identifying economic equilibria and general policy recommendations challenging. The potentially substantial benefits, coupled with the technical, social, and economic uncertainties surrounding gene drives, suggest that a responsible course of action is to move forward while maintaining regulatory flexibility and conducting research to resolve key uncertainties.
Gene drive inhibition by the anti-CRISPR proteins AcrIIA2 and AcrIIA4 in Saccharomyces cerevisiae
3957Basgall, EMG, S. C.; Goeckel, M. E.; Giersch, R. M.; Roggenkamp, E.; Schrock, M. N.; Halloran, M.; Finnigan, G. C., Microbiology-Sgm, 164:464-474. 2018-01-15 00:00:00.
Given the widespread use and application of the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas gene editing system across many fields, a major focus has been the development, engineering and discovery of molecular means to precisely control and regulate the enzymatic function of the Cas9 nuclease. To date, a variety of Cas9 variants and fusion assemblies have been proposed to provide temporally inducible and spatially controlled editing functions. The discovery of a new class of 'anti-CRISPR' proteins, evolved from bacteriophage in response to the prokaryotic nuclease-based immune system, provides a new platform for control over genomic editing. One Cas9-based application of interest to the field of population control is that of the 'gene drive'. Here, we demonstrate use of the AcrIIA2 and AcrIIA4 proteins to inhibit active gene drive systems in budding yeast. Furthermore, an unbiased mutational scan reveals that titration of Cas9 inhibition may be possible by modification of the anti-CRISPR primary sequence.
A CRISPR–Cas9-based gene drive platform for genetic interaction analysis in Candida albicans
4013Shapiro, RSC, Alejandro; Porter, Caroline B. M.; Hamblin, Meagan; Kaas, Christian S.; DiCarlo, James E.; Zeng, Guisheng; Xu, Xiaoli; Revtovich, Alexey V.; Kirienko, Natalia V.; Wang, Yue; Church, George M.; Collins, James J., Nature Microbiology, 3:73-82. 2018-01-11 00:00:00.
Candida albicans is the leading cause of fungal infections; yet, complex genetic interaction analysis remains cumbersome in this diploid pathogen. Here, we developed a CRISPR–Cas9-based ‘gene drive array’ platform to facilitate efficient genetic analysis in C. albicans. In our system, a modified DNA donor molecule acts as a selfish genetic element, replaces the targeted site and propagates to replace additional wild-type loci. Using mating-competent C. albicans haploids, each carrying a different gene drive disabling a gene of interest, we are able to create diploid strains that are homozygous double-deletion mutants. We generate double-gene deletion libraries to demonstrate this technology, targeting antifungal efflux and biofilm adhesion factors. We screen these libraries to identify virulence regulators and determine how genetic networks shift under diverse conditions. This platform transforms our ability to perform genetic interaction analysis in C. albicans and is readily extended to other fungal pathogens.
CRISPR-based gene drives for pest control
3992McFarlane, GRW, C. Bruce A.; Lillico, Simon G., Trends in Biotechnology, 36:130-133. 2018-01-10 00:00:00.
Clustered regularly interspaced short palindromic repeats (CRISPR)-based gene drives (GDs) could be used to spread desirable genetic elements through wild populations. With the imminent development of this technology in vertebrates, we believe that it is timely to highlight two forms of sex-ratio distorting GDs that show potential as pest management tools.
Veni, vidi, vici: the success of wtf meiotic drivers in fission yeast
3990López Hernández, JFZ, Sarah E., Yeast, 35:447-453. 2018-01-08 00:00:00.
Meiotic drivers are selfish DNA loci that can bias their own transmission into gametes. Owing to their transmission advantages, meiotic drivers can spread in populations even if the drivers or linked variants decrease organismal fitness. Meiotic drive was first formally described in the 1950s and is thought to be a powerful force shaping eukaryotic genomes. Classic genetic analyses have detected the action of meiotic drivers in plants, filamentous fungi, insects and vertebrates. Several of these drive systems have limited experimental tractability and relatively little is known about the molecular mechanisms of meiotic drive. Recently, however, meiotic drivers were discovered in a yeast species. The Schizosaccharomyces pombe wtf gene family contains several active meiotic drive genes. This review summarizes what is known about the wtf family and highlights its potential as a highly tractable experimental model for molecular and evolutionary characterization of meiotic drive.
Development of a multi-locus CRISPR gene drive system in budding yeast
4029Yan, YF, Gregory C., Scientific reports, 8:17277-17277. 2018-01-07 00:00:00.
The discovery of CRISPR/Cas gene editing has allowed for major advances in many biomedical disciplines and basic research. One arrangement of this biotechnology, a nuclease-based gene drive, can rapidly deliver a genetic element through a given population and studies in fungi and metazoans have demonstrated the success of such a system. This methodology has the potential to control biological populations and contribute to eradication of insect-borne diseases, agricultural pests, and invasive species. However, there remain challenges in the design, optimization, and implementation of gene drives including concerns regarding biosafety, containment, and control/inhibition. Given the numerous gene drive arrangements possible, there is a growing need for more advanced designs. In this study, we use budding yeast to develop an artificial multi-locus gene drive system. Our minimal setup requires only a single copy of S. pyogenes Cas9 and three guide RNAs to propagate three gene drives. We demonstrate how this system could be used for targeted allele replacement of native genes and to suppress NHEJ repair systems by modifying DNA Ligase IV. A multi-locus gene drive configuration provides an expanded suite of options for complex attributes including pathway redundancy, combatting evolved resistance, and safeguards for control, inhibition, or reversal of drive action.
Tuning CRISPR-Cas9 gene grives in Saccharomyces cerevisiae
4009Roggenkamp, EG, Rachael M.; Schrock, Madison N.; Turnquist, Emily; Halloran, Megan; Finnigan, Gregory C., G3-Genes Genomes Genetics, 8:999. 2018-01-07 00:00:00.
Control of biological populations is an ongoing challenge in many fields, including agriculture, biodiversity, ecological preservation, pest control, and the spread of disease. In some cases, such as insects that harbor human pathogens (e.g., malaria), elimination or reduction of a small number of species would have a dramatic impact across the globe. Given the recent discovery and development of the CRISPR-Cas9 gene editing technology, a unique arrangement of this system, a nuclease-based “gene drive,” allows for the super-Mendelian spread and forced propagation of a genetic element through a population. Recent studies have demonstrated the ability of a gene drive to rapidly spread within and nearly eliminate insect populations in a laboratory setting. While there are still ongoing technical challenges to design of a more optimal gene drive to be used in wild populations, there are still serious ecological and ethical concerns surrounding the nature of this powerful biological agent. Here, we use budding yeast as a safe and fully contained model system to explore mechanisms that might allow for programmed regulation of gene drive activity. We describe four conserved features of all CRISPR-based drives and demonstrate the ability of each drive component—Cas9 protein level, sgRNA identity, Cas9 nucleocytoplasmic shuttling, and novel Cas9-Cas9 tandem fusions—to modulate drive activity within a population.
Using CRISPR-based gene drive for agriculture pest control
13621V. Courtier-Orgogozo, B. Morizot and C. Boëte, EMBO Reports, 18:1481. 2017-09-01 13:15:07.
The authors respond to comments to their publication 10.15252/embr.201744205
Illinois study advances possibility of genetic control for major agricultural weeds
11589L. Quinn, ACES News, 2017-07-17 15:35:43.
Waterhemp and Palmer amaranth, two aggressive weeds that threaten the food supply in North America, are increasingly hard to kill with commercially available herbicides. A novel approach known as genetic control could one day reduce the need for these chemicals. Now, scientists are one step closer.
Agricultural pest control with CRISPR-based gene drive: time for public debate
13636V. Courtier-Orgogozo, B. Morizot and C. Boëte, EMBO Reports, 18:878-880. 2017-06-01 14:19:16.
Gene drive technology to control disease vectors or pests has great potential for addressing humanitarian and public health problems. Its application for pest control in agriculture, however, raises important environmental, social and ethical issues.
Is it time for synthetic biodiversity conservation?
4062Piaggio, AJS, G.; Seddon, P. J.; Alphey, L.; Bennett, E. L.; Carlson, R. H.; Friedman, R. M.; Kanavy, D.; Phelan, R.; Redford, K. H.; Rosales, M.; Slobodian, L.; Wheeler, K., Trends in Ecology & Evolution, 32:97-107. 2017-01-20 00:00:00.
Evidence indicates that, despite some critical successes, current conservation approaches are not slowing the overall rate of biodiversity loss. The field of synthetic biology, which is capable of altering natural genomes with extremely precise editing, might offer the potential to resolve some intractable conservation problems (e.g., invasive species or pathogens). However, it is our opinion that there has been insufficient engagement by the conservation community with practitioners of synthetic biology. We contend that rapid, large-scale engagement of these two communities is urgently needed to avoid unintended and deleterious ecological consequences. To this point we describe case studies where synthetic biology is currently being applied to conservation, and we highlight the benefits to conservation biologists from engaging with this emerging technology.
wtf genes are prolific dual poison-antidote meiotic drivers
4060Nuckolls, NLN, M. A. B.; Eickbush, M. T.; Young, J. M.; Lange, J. J.; Yu, J. S.; Smith, G. R.; Jaspersen, S. L.; Malik, H. S.; Zanders, S. E., eLife, 6:e26033. 2017-01-18 00:00:00.
Meiotic drivers are selfish genes that bias their transmission into gametes, defying Mendelian inheritance. Despite the significant impact of these genomic parasites on evolution and infertility, few meiotic drive loci have been identified or mechanistically characterized. Here, we demonstrate a complex landscape of meiotic drive genes on chromosome 3 of the fission yeasts Schizosaccharomyces kambucha and S. pombe. We identify S. kambucha wtf4 as one of these genes that acts to kill gametes (known as spores in yeast) that do not inherit the gene from heterozygotes. wtf4 utilizes dual, overlapping transcripts to encode both a gamete-killing poison and an antidote to the poison. To enact drive, all gametes are poisoned, whereas only those that inherit wtf4 are rescued by the antidote. Our work suggests that the wtf multigene family proliferated due to meiotic drive and highlights the power of selfish genes to shape genomes, even while imposing tremendous costs to fertility.
Engineering species-like barriers to sexual reproduction
4057Maselko, MH, Stephen C.; Chacón, Jeremy M.; Harcombe, William R.; Smanski, Michael J., Nature Communications, 8:883. 2017-01-15 00:00:00.
Controlling the exchange of genetic information between sexually reproducing populations has applications in agriculture, eradication of disease vectors, control of invasive species, and the safe study of emerging biotechnology applications. Here we introduce an approach to engineer a genetic barrier to sexual reproduction between otherwise compatible populations. Programmable transcription factors drive lethal gene expression in hybrid offspring following undesired mating events. As a proof of concept, we target the ACT1 promoter of the model organism Saccharomyces cerevisiae using a dCas9-based transcriptional activator. Lethal overexpression of actin results from mating this engineered strain with a strain containing the wild-type ACT1 promoter.
The End of the GMO? Genome Editing, Gene Drives and New Frontiers of Plant Technology
15368K. L. Hefferon and R. J. Herring, Review of Agrarian Studies, 7. 2017-01-01 21:40:33.
mprovements to agriculture will constitute one of the world’s greatest challenges in the coming century. Political and social controversies, as well as complications of plant breeding, intellectual property, and regulation, have compromised the promised impact of genetically engineered – typically transgenic – crops designated as “GMOs.” Genome editing is a new suite of molecular tools for assisting biologists identify genes that control agronomic traits such as drought tolerance and pest resistance, as well as to elucidate how expression of these genes is intertwined within the functional framework of the cell. This technology has recently gained momentum for its ability to accelerate the crop breeding process in an unprecedented fashion and expand the range of crop varieties with improved precision and lower costs. This review explains the basic concepts and provides examples of how genome editing could help address the United Nation’s Sustainable Development Goals with respect to food, agriculture, and medicine. It concludes with a discussion of the potential social impact of genome editing and gene drive. These effects are contingent on the resolution of novel ethical and regulatory challenges that add new layers of complexity to societal questions of appropriate technology, in agriculture and beyond. We expect these questions to replace the irresolvable GMO debate.
Science and Technology Committee Genetically Modified Insects
16058UK Parliament, UK Parliament, 2015-12-17 21:18:14.
The UK is a world leader in the development of this technology. The European Union’s regulatory process, however, is likely to hold back progress. There is a moral duty to test the potential of the technology. We therefore support further research and call for action to test the efficiency of the EU process via a trial which should also be used to drive public engagement. GM insect technology has already been trialled for dengue transmitting mosquitoes.
What is Gene Drive?
4717Entomological Society of America, 2015-07-01 00:00:00.
A fact sheet from the Entomological Society of America.
Regulatory experience and challenges for the release of GM insects
4135Beech, C, Journal Fur Verbraucherschutz Und Lebensmittelsicherheit-Journal of Consumer Protection and Food Safety, 9:S71-S76. 2014-01-13 00:00:00.
Genetically modified (GM) insects are a potentially valuable new tool for the biological control of insect pests of humans, animals and plants. Considerable progress has been made recently in transfer of GM insects from the laboratory to release and evaluation in the environment. As with other new genetic technologies, regulatory agencies have often found it challenging to determine the regulatory regime under which they should be evaluated, and have either adapted existing regulatory frameworks or adopted new ones. No country has legislation specifically for GM insects. However, irrespective of the regulatory regime under which they are evaluated, the purpose of their regulation remains the same; to protect human health and the environment. Consequently there are evaluation themes common to their regulatory scrutiny, which are elucidated here. There have also been some challenges and issues encountered during the risk evaluation for field release of GM insects, and this paper will highlight some of these to assist others when considering policy, regulation and assessment of GM insects. Useful regulatory and policy precedents also exist from the regulation of biological control agents and the global protection of plants from pests under the International Standards for Phytosanitary Measures (ISPM) framework. Where countries do not have existing regulations, these evaluation instruments could have the potential to be adapted to form a suitable framework for the assessment of risk for GM insects. Finally, some considerations for future policy and regulation in this area are discussed.
B chromosomes and genome size in flowering plants
4301Trivers, RB, A.; Palestis, B. G., Genome, 47:1-8. 2004-01-19 00:00:00.
B chromosomes are extra chromosomes found in some, but not all, individuals within a species, often maintained by giving themselves an advantage in transmission, i.e. they drive. Here we show that the presence of B chromosomes correlates to and varies strongly and positively with total genome size (excluding the Bs and corrected for ploidy) both at a global level and via a comparison of independent taxonomic contrasts. B chromosomes are largely absent from species with small genomes; however, species with large genomes are studied more frequently than species with small genomes and Bs are more likely to be reported in well-studied species. We controlled for intensity of study using logistic regression. This regression analysis also included effects of degree of outbreeding, which is positively associated with Bs and genome size, and chromosome number, which is negatively associated with Bs and genome size, as well as variable ploidy (more than one ploidy level in a species). Genome size, breeding system and chromosome number all contribute independently to the distribution of B chromosomes, while variable ploidy does not have a significant effect. The genome size correlates are consistent with reduced selection against extra DNA in species with large genomes and with increased generation of B sequences from large A genomes.
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