A retrotransposon insertion in MUTL-HOMOLOG 1 affects wild rice seed set and cultivated rice crossover rate

• DOI: 10.1093/plphys/kiac378
• Publication Date: 2022-08-17T14:08:14Z
• Authors: Kun Liu; Erwang Chen; Zhoulin Gu; Bingxin Dai; Ahong Wang; Zhou Zhu; Qi Feng; Congcong Zhou; Jingjie Zhu; Yingying Shangguan; Yongchun Wang; Zhen Li; Qingqing Hou; Danfeng Lv; Changsheng Wang; Tao Huang; Zixuan Wang; Xuehui Huang; Bin Han
• Keywords: Oryza rufipogon; Retrotransposon

Abstract Wild rice (Oryza rufipogon) has a lower panicle seed setting rate (PSSR) and gamete fertility than domesticated sativa), but the genetic mechanisms of this phenomenon remain unknown. Here, we cloned null allele OsMLH1, an ortholog MutL-homolog 1 to yeast mammals, from wild O. rufipogon W1943 revealed 5.4-kb retrotransposon insertion in OsMLH1 is responsible for low PSSR rice. In contrast wild-type, near isogenic line NIL-mlh1 exhibits defective crossover (CO) formation during meiosis, resulting reduced pollen viability, partial embryo lethality, PSSR. Except mutant mismatch repair gene postmeiotic segregation (Ospms1), all other MutL mutants sativa indica subspecies displayed male female semi-sterility similar NIL-mlh1, less severe those japonica subspecies. MLH1 MLH3 did not contribute additive fashion fertility. Two types heterodimers, MLH1-PMS1 MLH1-MLH3, were identified rice, only latter functions promoting meiotic CO formation. Compared varieties, cultivars had greater numbers events per meiosis. Our results suggest that may be caused by different defects, have substantially rates discrepancy between mlh1 mlh3 mutants.