种子是植物繁殖的基础，其大小是决定植物产量的关键性状之一。因此，关于种子大小调控机制的研究一直受到人们的重视。本项目前期筛选到拟南芥种子变大的突变体ssr1（seed size regulator 1），其种子相比野生型显著增大，粒重增加约40%；同时突变体的角果变大，每个角果的种子数目增加约12%。因此SSR1是控制种子产量性状的关键基因。遗传分析显示，SSR1基因受到BR信号的调控，并作用于SHB1-MINI3途径的下游。本项目将在前期工作的基础上，进一步深入研究SSR1调控种子大小发育的分子机理，明确SSR1介导的分子遗传网络。研究结果将为理解种子大小决定的机理以及作物高产育种提供重要信息。

Seed is a basis of plant propagation, and is also an important agronomic trait. Despite the importance of seed size, relatively little is known about the genetic and molecular mechanisms that control seed size. Previously, we identified that the ssr1 mutants gave rise to larger seeds than the wild type in Arabidopsis. The average seed size of the ssr1 mutants was approximately 140% that of the wild type. Fully elongated ssr1 mutant siliques were longer and wider than wild-type ones. The seed numbers per silique of the ssr1 mutants was approximately 112% that of the wild type. Therefore, we thought SSR1 was a key factor of seed size control. Genetic experiments showed that SSR1 acted downstream of BR signaling and SHB1-MINI3 pathways that controlling the seed size. In this study, we will reveal the molecular mechanisms of SSR1 in seed size determination and establish a genetic and molecular framework of SSR1 for controlling seed size in Arabidopsis. The results will provide the important information to understand the mechanisms of seed size regulation and improve crop yield.