OlCHR, encoding a chromatin remodeling factor, is a killer causing hybrid sterility between rice species Oryza sativa and O. longistaminata

Abstract

The genetic mechanisms of reproductive isolation have been widely investigated within Asian cultivated rice ( Oryza sativa ); however, relevant genes between diverged species have been in sighted rather less. Herein, a gene showing selfish behavior was discovered in hybrids between the distantly related rice species Oryza longistaminata and O. sativa . The selfish allele S13 l in the S13 locus impaired male fertility, discriminately eliminating pollens containing the allele S13 s from O. sativa in heterozygotes ( S13 s / S13 l ). Genetic analysis revealed that a gene encoding a chromatin-remodeling factor (CHR) is involved in this phenomenon and a variety of O. sativa owns the truncated gene OsCHR745 , whereas its homologue OlCHR has a complete structure in O. longistaminata . CRISPR-Cas9-mediated loss of function mutants restored fertility in hybrids. African cultivated rice, which naturally lacks the OlCHR homologue, is compatible with both S13 s and S13 l carriers. These results suggest that OlCHR is a Killer gene, which leads to reproductive isolation.