水稻S5互作基因qSIG3.1的图位克隆与机理研究

亚洲栽培稻由籼稻和粳稻两个亚种组成。虽然亚种间杂种优势强于亚种内的，但亚种间杂种不育妨碍了其杂种优势的有效利用。克服其杂种不育将有助于提高杂交稻的增产潜力。S5是控制水稻杂种雌配子育性的主效位点，对亚种间杂种的结实率影响极大。我们已发表结果表明，S5位点由三个紧密连锁的基因组成杀手-护卫系统并调控杂种育性。进一步的研究表明，另有背景基因参与S5的杂种不育调控。本研究拟探索背景基因与S5互作导致杂种败育的机理。我们通过图位克隆方法已找到几个跟S5互作的背景基因，其中效应最大的qSIG3.1已被精细定位，并通过遗传转化验证了候选基因的功能。到目前为止，还未见水稻中与S5互作的基因被克隆的报道，所以本研究既有重大科学价值，又具有新颖性。本研究有助于增进对稻种起源、演化的认识，也会有助于亚种间杂交稻育种。

Asian cultivated rice (Oryza sativa L.) comprises two subspecies, indica and japonica rice. Indica-japonica intersubspecific hybrid rices have stronger heterosis than intrasubspecific ones, whereas intersubspecific hybrid sterility hampers the utilization of its heterosis. Overcoming interspecific hybrid sterility between Indica and japonica rice will help to increase the yield potential of hybrid rice. S5 is among the loci with the largest effect on hybrid fertility of female gamete, and it can affect the seed-setting rate of intersubspecific hybrids greatly. Our published results showed that the S5 locus consists of three closely linked genes, which form a killer-protector system and regulate hybrid fertility. Further research shows that background genes are involved in the regulation of hybrid sterility at S5. This study intends to elucidate the biological basis of interspecific hybrid abortion caused by interaction between S5 and background genes. We have found several S5-interacting background genes via map-based cloning. The major-effect gene, qSIG3.1 has been fine-mapped and validation of gene function is conducted via genetic transformation . So far, there has been no report on the cloning of S5-interacting genes in rice, so this study has both great scientific value and novelty. Results will improve our understanding on origin and evolution of rice, and would also contribute to intersubspecific hybrid rice breeding.