Three Stunning Ways Biologists Aim to Edit Animal and Plant Genes to Fight Diseases and Extinction

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Three Stunning Ways Biologists Aim to Edit Animal and Plant Genes to Fight Diseases and Extinction

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Sandy Ong,  Smithsonian Magazine,  2026.

In the summer of 1904, Herman Merkel, chief forester at the Bronx Zoo, in New York City, was making his usual rounds across the property when he noticed something strange growing on American chestnut trees: misshapen constellations of swollen, orange-brown cankers. Unbeknownst to Merkel, his observations were the first signs of what would later be referred to as “the greatest ecological disaster in North America since the Ice Age.” Further investigation revealed that the culprit was a fungus called Cryphonectria parasitica, or chestnut blight, which slips its spores through cracks in the bark and fatally severs a tree’s water and nutrient supply. The pathogen was a stowaway that had arrived on imported Japanese chestnut trees, which are resistant—but on American soil, it proved to be a swift and merciless killer. Barely a year later, the blight had claimed nearly all the zoo’s chestnuts—as well as those in the surrounding Bronx parks. By the 1950s, it had wiped out 99 percent of the species’ population across the Eastern United States, where more than four billion of the towering trees had once so blanketed the landscape that a squirrel was said to be able to travel from Maine to Georgia on chestnut branches alone.

Since then, scientists have tried, with little success, to bring the trees back from the brink. Today, American chestnuts are considered functionally extinct. Full-sized trees are hard to come by; mainly roots and shoots remain. Scientists have bred hybrid American-Chinese chestnut trees, but planting fully native species is important for ecological restoration goals, says Andrew Newhouse, director of the American Chestnut Research and Restoration Project at the State University of New York (SUNY). Thanks to an emerging field, the iconic trees—and other imperiled species—could one day be restored. The discipline, called synthetic biology, relies on editing organisms’ DNA to introduce new genes or modify existing ones, essentially reprogramming life to fight disease, clean up the environment, increase food production and more. For chestnut trees, making changes to their genome could boost their resistance to the blight.