水稻抽穗期是决定品种季节与区域适应性的重要农艺性状，其长短主要决定于基本营养生长性、感光性和感温性。但目前，对感温性的遗传基础尚甚不清楚，基因定位或克隆均鲜有报道。在前期研究中，我们精细定位了一个感温性QTL qHd1；通过区间测序与基因表达分析，推测OsMADS51为目标基因。在本项目中，首先，对该基因进行遗传互补验证与表达模式分析；其次，结合转录组测序、酵母单杂和荧光素酶转录活性检测，解析OsMADS51调控水稻抽穗感温反应的分子网络；并在此基础上，筛选少数上/下游基因，利用CRISPR-Cas9系统获得相应的功能缺失突变体，验证其与OsMADS51的遗传关系。同时，分析104份中国南方稻区主要籼稻常规品种的感温反应及其在OsMADS51位点的等位变异特点。通过研究，揭示OsMADS51调控水稻抽穗期感温性的分子遗传机制，明确其育种应用现状与潜力，为品种的抽穗期改良提供理论与技术参考。

Heading date determines the growing area and seasons of rice varieties, and itself is determined by the basic vegetative growth period, photoperiod-sensitivity and thermo-sensitivity. But currently, little is known about the genetic basis that controls the timing of rice heading in response to temperature variations, neither on gene mapping nor on cloning. We have previously fine-mapped a rice heading date QTL qHd1, which exhibited thermos-sensitivity. By sequence comparison and expression analysis, OsMADS51 was identified as the potential candidate underlying qHd1. In this proposal, transgenic complementation experiments for OsMADS51 will be firstly conducted and then its expression patter will be tested in leaves in different developmental phases. RNA-Seq analysis, Yeast one-hybrid screening, and Luciferase assay will be done to unravel the molecular network by which OsMADS51 controls rice heading in response to temperature variations. Based on this, several interesting genes upstream or downstream of OsMADS51 will be selected as the targeted loci for genome editing by CRISPR-Cas9, so as to confirm their genetic relationship with OsMADS51. On the other hand, 104 representative inbred varieties of indica rice grown in Southern China will be tested for the thermo-sensitivity and the haplotypes of OsMADS51. This research work is expected to have a molecular understanding of how temperature influences rice heading date through the OsMADS51 pathway and found out the current situation and potentials of OsMADS51 in rice breeding, which would build up a solid theoretical and technological basis for improvement of rice heading date.