BR抑制SUBRI1小肽信号途径促进植物生长发育的机制

油菜素内酯(BR)在植物生长发育诸多阶段发挥重要的作用。在细胞水平上，BR能够调控细胞伸长、细胞分裂以及细胞分化等过程。在本项目中，我们前期通过遗传筛选得到BR受体(BRI1)强表型突变体bri1-101的抑制子subri1-1 bri1-101，该抑制子中编码小肽SUBRI1的基因发生突变。遗传学、转录组学分析表明，SUBRI1可能通过抑制细胞伸长对植物生长发育产生抑制作用。进一步的实验发现，小肽SUBRI1并不参与BR信号的传导，但BR能够抑制SUBRI1表达而促进植物生长发育。因此，我们将采用遗传学、分子生物学和生物化学的方法，研究SUBRI1信号通路对细胞伸长的调节以及BR抑制SUBRI1表达的分子机制，为深入研究BR在促进植物生长发育中的作用提供参考。

Brassinosteroids (BR) are a class of unique plant hydroxysteroids that play important roles in a wide range of plant physiological and developmental processes. At the cellular level, BR can regulate cell elongation, cell division and cell differentiation. Using a severely-dwarfed Arabidopsis BR receptor mutant, bri1-101, we performed a large-scale suppressor screen and identified a semi-dominant extragenic suppressor subri1-1 bir1-101. Genetic mapping coupled with whole genome sequencing revealed that SUBRI1 encode a putative peptide. Genetics and transcriptomics analysis imply that SUBRI1 signaling might inhibit cell elongation to repress plant growth. Interestingly, subri1 mutation cannot affect BR signaling, however, BRs negatively regulates the SUBRI1 transcript abundance in a BRI1-dependent manner. Taken together, our results suggest that BRs suppress the SUBRI1-mediated signaling pathway to promote plant growth. In this research, we will apply genetics, molecular biology and biochemical methods to reveal the function of SUBRI1 signaling pathway in cell elongation, and the mechanism of BR inhibition SUBRI1 signaling pathway. Moreover, our study will also provide significant insight into the mechanisms of BR signaling in promoting cell elongation to mediate plant growth and development.