A natural gene drive element confers speciation in rice

Tags: Agriculture, Genetic incompatibilities, Toxin-antidote
Y. Li, S. Liu and R. Shen, Chinese Science Bulletin, 68:3400-3402. 2023.

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.