水稻籼粳杂种不育性的遗传机理及杂种优势利用

Genetic Mechanism of Hybrid Sterility and Utilization of Indica-japonica Inter-subspecific Heterosis in Rice

籼稻和粳稻是亚洲栽培稻的两个亚种,两者在形态、生理以及基因水平上存在显著差异,亚种间的遗传差异将会产生强大的杂种优势,能进一步提高水稻的产量潜力,但是,籼粳亚种间的F_(1)杂种不育性严重阻碍了杂种优势的利用。杂种不育性是一种合子后生殖隔离,具有普遍性和复杂性,受多个不育基因座控制。广亲和品种的发现为克服亚种间杂种不育提供可能,该材料无论与籼稻还是粳稻杂交,F_(1)杂种都能正常结实或结实率较高。概述了籼稻与粳稻间差异,剖析了水稻籼粳亚种间杂种不育的遗传基础、已鉴定的杂种不育主效QTL与基因,分析了已克隆杂种不育基因的分子作用机制及广亲和基因的功能。据此提出利用籼粳架桥培育亚种间渗入水稻、聚合育种培育广亲和系和粳型亲籼系,以及应用基因编辑技术创制广亲和系等途径,能够克服籼粳亚种间杂种不育性,精准化改良籼粳杂种的结实率,从而实现亚种间杂种优势的利用。籼粳亚种间杂交水稻的推广应用,将会推动水稻产业的又一次重大变革。

Asian-cultivated rice(Oryza sativa L.)consists of two subspecies,indica(Oryza sativa L.indica)and japonica(Oryza sativa L.japonica)subspecies.There are considerable differences between them in morphology,physiology and gene level.The stronger heterosis generated by the genetic differences between inter-subspecies could improve the yield potential of rice.However,the application of heterosis in indica-japonica subspecies is limited because of the serious hybrid sterility in F_(1) hybrid.Hybrid sterility,a common form of postzygotic reproductive isolation,is universal and complex,controlled by multiple hybrid sterility loci.The discovery of wide-compatible varieties(WCVs)provides the possibility to overcome interspecific hybrid sterility as the F_(1) hybrids show normal fertility whether WCVs crossed with indica or japonica rice.In this paper,we summarize the indica-japonica divergence,the genetic basis of hybrid sterility in indica-japonica subspecies,the identified hybrid sterility QTL and genes,and analyze the molecular mechanisms of the cloned hybrid sterility genes and the function of wide-compatible genes.On this basis,we propose four approaches to overcome inter-subspecific hybrid sterility,and improve the fertility of indica-japonica F_(1) hybrids precisely,including breeding inter-subspecific introgression rice,developing indica-compatible japonica lines and wide-compatible lines,and creating wide-compatible genes by gene editing technology.The application of indica-japonica hybrid rice will promote a major change in rice industry.