水稻野败型细胞质雄性不育及其恢复性的分子遗传基础

rice (Oryza sativa L.) is a staple food crop for more than half of the world's human population. Apart from the semi-dwarf breeding, hybrid rice is another best-known successful story in the modern crop breeding history. This achievement mainly thanks to the discovery of a male-sterile cytoplasm from a wild rice species O. rufipogon in 1970s, which is called Wild Abortive type of CMS (CMS-WA), and the successful use of this cytoplasm resource to breed a number of CMS-WA lines. CMS-WA/Rf system is superior for its complete and stable male sterility and better fertility restoration by restorer lines; hybrid rice varieties bred with this system have about 20% or more yield advantage over improved inbred varieties. Three-line hybrid rice using the CMS-WA system has been cultivated commercially in China from 1976, and has occupied ~55% (~15-17 million hectares) of the total rice planting area in China since 1990's. Therefore, the CMS-WA-based hybrid rice has contributed tremendously to the food security and given a great impact to agriculture. .Genetic studies show that CMS-WA is sporophytic in nature, and the male fertility is restored by two major Rf loci, Rf3 and Rf4, locating on the chromosomes 1 and 10, respectively. However, molecular nature of the CMS-WA/Rf system has not been revealed. In a previous study, we cloned a novel mitochondrial gene WA352 conferring CMS-WA, and found that WA352 accumulated specifically in anthers, and directly interacts with COX11, a nuclear-encoded component of the mitochondrial respiratory chain. In this project, we will carry out the following studies: (1) Investigation of the origination of the WA352 locus in wild and cultivated rice species; (2) Cloning and functional study of Rf3 and Rf4 and revealing the molecular mechanisms on fertility restoration; (3) Revealing the molecular mechanism on the regulation of the anther-specific accumulation of WA352; and (4) Understanding the molecular and cellular mechanisms on the CMS induction based on the WA352-COX11 interaction. The results of this project will provide insights into molecular genetic basis for this important CMS/Rf sytem, and promote the better utilization of heterosis in rice.

细胞质雄性不育（CMS）及其恢复（Rf）系统是作物杂种优势利用的有用工具，也是研究核质基因互作的理想模型。基于野败型CMS-WA/Rf系统培育的三系杂交稻已在我国长期广泛应用，对国家粮食增产和安全供给做出了巨大的贡献。但CMS-WA/Rf系统的分子遗传基础仍不清楚。我们前期工作克隆了野败型CMS基因WA352，发现WA352蛋白在花药特定时期产生，并与1个核编码的线粒体蛋白COX11互作。在此基础上，本项目拟研究WA352的起源进化，恢复基因Rf3和Rf4的克隆及其与WA352的互作与育性恢复机制, WA352蛋白在雄性器官和营养器官差异积累的调控机制，WA352与COX11的互作与不育发生的分子机制和细胞学机制。本研究全面而深入地阐明野败型CMS-WA/Rf系统的分子遗传及其分子作用机制，对其它CMS-WA/Rf系统的分子基础研究和充分利用作物杂种优势提高产量具有重要的理论指导和实践意义

细胞质雄性不育（CMS）及其恢复（Rf）系统是作物杂种优势利用的有用工具，也是研究核质基因互作的理想模型。基于野败型CMS-WA/Rf 系统培育的三系杂交稻已在我国长期广泛应用，对国家粮食增产和安全供给做出了巨大的贡献。但CMS-WA/Rf 系统的分子遗传基础仍不清楚。本项目在克隆了野败型CMS基因WA352的基础上，进行以下研究：（1）WA352与COX11互作与不育发生的分子与细胞学机制；（2）恢复基因的克隆及其作用机制；（3）WA352蛋白特异性积累机制；和（4）WA352基因的起源进化研究。本项目在分子水平上阐明了水稻CMS-WA/Rf系统的分子作用机制：（a）解析了CMS-WA基因基因WA352 与COX11互作产生绒毡层细胞活性氧爆发和绒毡层提前凋亡而导致不育发生的分子与细胞学机制；（b）定位克隆了恢复基因Rf3和Rf4，发现Rf4编码PPR蛋白，并存在多种复等位变异，首次发现Rf3是一种新型的长链非编码恢复基因；阐明了它们对对WA352的mRNA和蛋白的表达调控机制；（c）发现WA352蛋白具有2个受未知因子攻击降解的靶点，可能与其在花药特定发育时期的特异性积累机制有关；（d）成功追踪了WA352等不育基因的起源进化路径，解析了CMS基因的产生机制，提出一个植物线粒体基因组的“动态重组--原基因形成--序列和拷贝数变异--功能基因生成”的新基因起源进化模型。本项目全面阐明了整个CMS-WA/Rf系统的分子遗传基础，为其它CMS/Rf系统的研究和作物杂种优势利用提供了理论指导；本项目提供的恢复基因序列及其多态性分子标记信息已被多个育种单位用于杂交稻育种。本项目发表论文5篇，获发明专利1项，获大北农科技奖一等奖1项