基于单片段代换系的水稻苗期耐冷QTL的精细定位和聚合育种

水稻苗期低温冷害是我国很多稻区的主要灾害之一。培育苗期耐冷品种不仅是目前水稻生产上急需解决的问题，更是适应农业现代化的需要。分子育种被认为是解决水稻苗期低温冷害的有效途径。但是，水稻苗期耐冷分子育种还未有成功的报道。准确鉴定效应较大并能稳定表达的耐冷QTL是水稻苗期耐冷分子育种取得突破的关键。本项目前期以优良品种“华粳籼74” 做轮回亲本构建的单片段代换系为材料，鉴定出3个苗期稳定表达的耐冷QTL，迄今未见这3个耐冷QTL被精细定位与克隆的报道。本项目拟在前期工作的基础上，将用代换作图法对3个耐冷QTL进行精细定位；并开展苗期耐冷QTL的聚合育种和3个耐冷QTL之间的互作效应分析。预期该项目的实施，不仅能预测这3个耐冷QTL的候选基因，获得的紧密连锁标记，可应用到分子育种中，而且首次实现苗期耐冷性聚合育种，获得的有显著苗期耐冷性优良聚合系有望应用于生产。

Cold stress at the seedling stage is one of the key abiotic stresses in rice production in China. Developing cold-tolerant variety is the most economical and effective way to prevent cold damage. Cold tolerance at the seedling stage is an important character for stable rice production, especially in direct-seeded rice cultivation, which is becoming desirable in many Asian countries due to labor-use efficiency, low water use, and lower expense compared with transplanting seedling. Only with molecular breeding, the cold tolerance rice breeding can make a breakthrough at the seedling stage. Three SSSLs bearing stable cold tolerance QTL were identified using single segment substitution lines (SSSLs) which were developed by using of Hua-jing-xian74, an elite indica variety from South China, as recipient. The three cold tolerance QTLs were mapped on chromosomes 3, 6 and 12, respectively. So far, there aren’t reports of fine mapping for the three cold tolerance QTLs and cold tolerance molecular breeding at seedling stage. On the basis of precedent researches, this project aims to carry out the following researches:(1) Performing fine mapping of the three cold tolerance QTLs with substitution mapping; (2) Performing the pyramiding breeding for cold tolerance at seedling stage and making epistasis analysis of the three cold tolerant QTLs in rice. The completion of this project not only acquired the predicted genes of the three cold tolerance QTLs, but also gained some pyramiding lines with strong cold tolerance at seedling stage. The markers closely linked with the cold tolerance QTLs could be used for molecular breeding, and the pyramiding lines prove for the first time that pyramiding breeding could be utilized for cold tolerane at seedling stage in rice.