Spontaneous movement of a retrotransposon generated genic dominant male sterility providing a useful tool for rice breeding

Male sterility in plants provides valuable breeding tools in germplasm innovation and hybrid crop production. However, genetic resources for dominant genic male sterility, which hold great promise to facilitate breeding processes, are extremely rare in natural germplasm. Here we characterized the Sanming Dominant Genic Male Sterility in rice and identified the gene SDGMS using a map-based cloning approach. We found that spontaneous movement of a 1978-bp long terminal repeat (LTR) retrotransposon into the promoter region of the SDGMS gene activates its expression in anther tapetum, which causes abnormal programmed cell death of tapetal cells resulting in dominant male sterility. SDGMS encodes a ribosome inactivating protein showing N-glycosidase activity. The activation of SDGMS triggers transcription reprogramming of genes responsive to biotic stress leading to a hypersensitive response which causes sterility. The results demonstrate that an ectopic gene activation by transposon movement can give birth to a novel trait which enriches phenotypic diversity with practical utility.