控制水稻种子大小和千粒重的基因GS1的克隆与功能研究

水稻种子大小是一个重要的产量性状、外观品质性状和驯化的靶标性状。在前期研究工作中我们在第1染色体上发现了一个新的、效应很大的同时控制水稻种子粒宽、粒长和千粒重的数量性状位点（GS1），但其分子基础不清楚。本项目在其工作基础上，拟先用图位克隆法将GS1精细定位到20 kb；通过比较测序、表观变异鉴定、比较表达等分析确定候选基因；利用转基因、突变体等分析来验证该基因的生物学功能；通过差异表达、酵母双杂交、免疫沉淀-质谱联用等分析鉴定下游或互作的蛋白，再用免疫共沉淀、双分子荧光互补、突变体或转基因等技术对互作蛋白进行生化和遗传上的双重验证，来剖析GS1调控种子大小的分子机理。另外，将利用533份世界水稻微核心种质对GS1进行遗传多样性和相关分析，确定适合于水稻遗传改良的优良等位基因。本研究的完成，不仅将丰富对种子大小分子调控机制的认识，还将为水稻分子育种提供新基因，在理论和实践上具有重要意义。

Rice grain size is an important yield trait, appearance quality trait and a target trait of domestication.In the previous study, we detected a new and major QTL (Quantitative Trait Locus), GS1, for rice grain width, grain length and 1000-grain weight, but the gene underlying the QTL and its regulating functions are unknown. In this project based on the previous work, we first plan to fine map GS1 to a 20-kb region using the map-based cloning method. Next, we will iendtify the candidate genes by the comparative sequencing ananlyses coupled with identifying putative epigenetic variations and comparative expression analyses, and then confirm the functional GS1 gene by the genetic transformation and mutant analyses. Moreover, we will first identify the putative down-stream genes and interacting proteins of GS1 using the differential expression, yeast-two-hybrid and IP-MS analyses, and then confirm these factors using both biochemical and genetic analyses, including Co-IP and BiFC, and genetic transformation and mutant analyses,respectively, to uncover the molecular mechanism of GS1 for regulating rice grain size.In addition, we will make the genetic divesity and association analyses to identify the favorable alleles of GS1 for rice genetic improvement using 533 rice mini-core accessions with a wide genetic variation wordwide. The isolating and fuctional analysis of the GS1 gene will not only make great contributions to comprehensively understanding the molecular regulation of seed size, but also provide a novel gene for molecular breeding, making good sense in both theory and practice.