籽粒大小的遗传改良对提高玉米单产具有重要意义。项目组前期已克隆了一个控制玉米籽粒大小基因RPC2，编码RNA聚合酶Ⅲ的第二个亚基，但其功能在植物中未见报道。本项目拟利用突变体遗传分析、表达分析、关联分析和遗传转化等各种遗传学手段，深入解析RPC2的生物学功能、基因作用方式及其在自然群体中有利等位变异；利用原位杂交、表达模式分析、转录组和小RNA组测序、蛋白免疫沉淀结合质谱分析、酵母双杂交等方法，阐明RPC2参与玉米籽粒发育的调控网络；通过对RPC2在玉米基因组中的结合位点研究，明晰RNA聚合酶Ⅲ转录的small RNA的种类，充实RNA聚合酶Ⅲ在植物中的功能。项目研究结果不仅可以解析调控植物籽粒发育的新途径，拓展我们对植物籽粒发育过程中基因表达调控的认识，也为玉米籽粒性状的遗传改良提供基因资源和理论指导。

The genetic improvement of grain size is of great significance to the improvement of maize yield per unit area. The gene RPC2 controlling kernel size in maze, which encodes the second subunit of RNA polymerase III, was cloned in previous study, but there was no report about its function in plants. In the present study, we want to analyze the biological function, gene action mode and the beneficial allelic variation of RPC2 gene using the genetic and molecular biological methods, such as genetic analysis, association analysis, genetic transformation, expression analysis etc. The methods of in situ hybridization, expression pattern analysis, RNA-seq, small RNA-seq, CoIP-MS and yeast hybridization were used to elucidate the regulatory network of RPC2 in maize kernel development. The binding sites of RPC2 in maize genome will be studied which will help us to clarify the types of small RNA transcribed by RNA polymerase III, and enrich the function of RNA polymerase III in plant. The results will could not only analyze a new regulation pathway of plant grain development and expand our understanding of gene expression regulation network during plant grain development, but also provide genetic resources and theoretical guidance for genetic improvement of the grain traits in maize.