器官大小决定着植物的生物产量，是植物重要的形态特征之一。植物器官大小受到严格的遗传调控，同时还受环境因素的影响。利用分子生物学等研究方法，已经发现了多个调控植物器官大小的作用因子，但这还远不能全面地理解植物调控自身器官大小的分子机理。继之前发现和研究了器官大小调控基因OSR1之后，我们又发现了一个新的植物器官大小调控基因OSR2(ORGAN SIZE-RELATED 2)。在拟南芥中过量表达OSR2导致转基因植株的器官显著增大。细胞学观察表明，这是由于转基因植株中细胞的数目和细胞大小均增加所致。在外施植物激素处理的情况下，OSR2的表达受乙烯和脱落酸的诱导。但是，OSR2调控植物器官大小的分子机制还不清楚。本项目将从分子遗传学，细胞生物学和生物化学等方面，对OSR2的功能做详细的研究。研究可望明确OSR2在调控植物器官大小方面的功能以及其发挥功能的分子机理。

The sizes of organs directly reflect the abilities of plant in energy conversation and storage, and also contribute a lot to the biomass and agronomic traits. The final size of plant organs is defined by intrinsically developmental programs and also greatly affected by the environmental factors. Several factors involved in plant organ size control have been characterized in Arabidopsis, but the molecular mechanism of how plants regulate their final organ size remains unclear. To identify other factors involved in plant organ size control, we used bioinformatics information and found a novel gene OSR2 (ORGAN SIZE-RELATED 2) related to organ size control after the work on the plant organ size regulating gene OSR1. Ectopic expression of OSR2 results in the enlarged organs in Arabidopsis, due to the increase of both cell number and cell size within these organs. After treating with plant hormones, the expression of OSR2 is induced by ethylene and ABA. However, the molecular mechanism of OSR2 regulating plant organ size is unknown. A combination of genetic, cytological and biochemical approaches will be used to investigate the roles of OSR2 in organ size control and to uncover the molecular mechanism.