对于多细胞生物而言，器官大小是个体形态的最直观体现。一个植物器官长到它的既定大小主要受细胞分裂和膨大过程的协同调控。虽然已经报道了一些调控两个过程的关键基因，但是协同调控机制还需深入研究。我们发现了一个调控植物器官大小的OSR基因家族，包括ARGOS、ARL、OSR1和OSR2。它们的异位表达都可以引起器官变大，但是细胞学行为却不尽相同，其中：ARGOS增加了细胞数目，ARL、OSR2增加了细胞大小，OSR1既增加细胞数目又增大了细胞大小，最终导致器官变大。进一步研究表明OSR家族的四个成员通过协同调控细胞分裂和膨大、进而调控器官大小。为了深入研究OSR家族的分子机制，我们拟利用酵母双杂交和免疫共沉淀的方法筛选互作蛋白，进行体内、外的互作验证。最终结合遗传学、细胞学和生物化学等方法进行功能鉴定，以期揭示OSR家族成员调控器官大小的分子机制和信号控制，为作物改良提供基因资源和理论依据。

For multicellular organisms, organ size is a fundamental attribute of body morphology. In plants, the growth of an organ to its characteristic size depends mainly on the coordination of cell proliferation and expansion. However, although some key genes regulating cell proliferation and expansion have been identified, the mechanism underlying the cooperative and coordinative regulation of two processes is largely elusive. We identified a gene family which had been implicated in the regulation of organ size and named ORGAN SIZE RELATED (OSR), including ARGOS, ARL, OSR1 and OSR2. Ectopic expression of four genes enlarged organs, but their cellular processes were quitely different. ARGOS controlled the growth of an organ mainly due to the increased cell number, and both ARL and OSR2 regulated the organ-size by increasing cell size, but OSR1 promoted organ growth by affecting both cell number and size and then enlarged the organs. Further analysis revealed that four OSR genes cooperatively regulate cell proliferation and expansion and thus the final organ size. To further elucidate the molecular mechanism of OSR family members, we try to screen the interacting proteins of OSRs by using the Y2H and Co-IP methods and then identify them in vivo and in vitro. Using genetic, cytological and biochemical approaches, we will dissect the function of OSR family members and these results will further our understanding of molecular mechanism and signaling control of how OSR members regulates organ size and will provide genetic resources and theoretical basis for crop improvement.