江西东乡普通野生稻芽期耐冷QTL qLTT1的克隆及功能鉴定

普通野生稻是亚洲栽培稻的野生祖先种，携带许多在栽培稻中已丢失或削弱的优异遗传基因。申请者所在课题组以优良籼稻品种93-11为轮回亲本构建的江西东乡野生稻渗入系为材料，通过芽期耐冷性鉴定，在第1染色体上定位了一个来自野生稻的耐冷QTL（qLTT1），并筛选出一个耐冷渗入系NID2。进一步利用该渗入系与93-11回交构建分离群体，将qLTT1限定在分子标记RM1244和RM3403之间。本项目将在此基础上，继续扩大分离群体，对耐冷QTL进行精细定位；同时结合QTL定位、RNA-seq表达谱分析以及生物信息学的方法确定qLTT1候选基因；利用多种分子生物学技术验证基因功能，初步构建其参与的水稻低温胁迫响应的遗传调控网络。研究结果不仅将为水稻芽期耐冷性分子育种提供新基因，而且将为揭示水稻耐冷性调控机理提供重要参考。

Common wild rice (Oryza rufipogon Griff.), the wild progenitor of Asian cultivated rice (O. sativa L.), carries many agronomically beneficial alleles which were lost or weakened during rice domestication. Using a set of introgression lines (ILs), derived from a cross between Dongxiang common wild rice and an indica cultivar 93-11, we have identified a major quantitative trait locus qLTT1 on chromosome 1, associating with low temperature tolerance at early seedling stage in Dongxiang common wild rice, and obtained a low temperature tolerant introgression line NID2 which harbored the O. rufipogon-derived qLTT1 allele. Using the secondary F2 population derived from the backcross between introgression line NID2 and the recipient parent 93-11, the QTL qLTT1 was narrowed down an interval from the markers RM1244 and RM3403 on chromosome 1. Based on the previous results, a large segregation population will be developed for fine-mapping the low temperature tolerance-related QTL qLTT1 from common wild rice. At the same time, the candidate gene of qLTT1 will be obtained through the strategy of combining QTL location, global expression profile, and bioinformatics analysis. Based on the annotation of candidate gene, the gene function and its regulatory pathway involved in cold tolerance will be analyzed using molecular biology approaches. The results in this study will provide a new genetic resource for improving cold tolerance at early seedling stage in rice breeding, and also provide new insights into the molecular mechanism underlying low temperature tolerance in rice.