植物激素油菜素内酯（BR）可有效地提高作物产量。拟南芥中BR信号转导网络研究得比较清楚，其中多个蛋白分子可被泛素化修饰。然而，相应的泛素连接酶却未有报道。本研究前期工作发现拟南芥中两个同源性较高的U-box类泛素连接酶PUB30和PUB31的功能缺失突变体（pub30 pub31）具有与BR生物合成或信号转导发生缺陷的突变体相似的表型。进一步的生理实验证明pub30 pub31双突变体属于BR不敏感突变体。生物化学分析表明PUB30和PUB31在体外具有自身泛素化的能力。酵母双杂交的结果说明PUB30或PUB31可与BR信号通路中的负调节因子BKI1相互作用。本项目拟研究PUB30和PUB31对BKI1功能的调控作用，阐明PUB30和PUB31参与调节BR信号转导过程的分子机理。这将为全面认识BR信号转导通路提供新的证据，为农业生产上提高作物产量提供科学依据与基因资源。

Plant hormone brassinosteroid (BR) could efficiently improve crop yield. BR signal transduction was deeply studied in Arabidopsis, in which many components were modified by ubiquitination. However, corresponding ubiquitin ligases have not been identified in BR signaling until now. We found PUB30 and PUB31 are highly homologous, and pub30 pub31 double mutants showed BR-deficient or BR-insensitive phenotype. Physiological tests displayed that pub30 pub31 double mutants are insensitive to BR. PUB30 and PUB31 were self-ubiquitination in vitro. By the yeast two-hybrid we found that PUB30 or PUB31 interacted with BKI1, a negative regulator in BR signaling. The project will focus on the regulation of PUB30 and PUB31 on BKI1 and elucidate the mechanism of PUB30 and PUB31 in regulating BR signaling transduction, which will provide us new evidence for understanding BR signaling transduction and provide theoretical basis and gene resource for improving crop yield.