鸟苷酸交换因子RopGEFs调控叶表皮铺板细胞形态发生的分子机制

Auxin is a multifunctional hormone essential for plant development and pattern formation. Recently, researches on morphogenesis of Arabidopsis leaf pavement cells reveal a novel auxin signal pathway mediated by transmembrane protein complexes containing ABP1 (Auxin binding protein 1) and TMKs (Receptor-like kinase). ABP1 / TMK receptor complexes can quickly activate small G protein signaling pathway to control pavement cell morphology. However, there is a great gap about the molecular mechanism underlying this new auxin receptor complex. RopGEFs (Guanine nucleotide exchange factors) can activate the small G-protein signaling and participate in a variety of developmental processes. According to our primary results of mutant phenotype analysis, ROP activity assay, protein interaction detection, we found RopGEFs participate in the ABP1/TMK mediating auxin signaling pathway. We speculate RopGEFs may be phosphorylated by TMKs and then activate membrane ROP signal. Our project aims to reveal the molecular mechanisms of RopGEFs on regulating pavement cell development by detection of TMKs and RopGEFs interactions and genetic analysis on the phenotype of pavement cells, further improve ABP1/TMK-mediated auxin signaling pathway.

生长素作为植物中最重要的激素之一能够调节植物几乎所有的生长过程。最近对铺板细胞形态发生的研究发现了一个新的由ABP1/TMK受体复合物介导的生长素信号通路。ABP1/TMK受体复合物可以快速激活小G蛋白信号途径从而控制细胞骨架的动态结构和细胞的形态建成。然而对于这个新的生长素受体复合物，与其相关的分子机制还有很大的空白未知。鸟苷酸交换因子RopGEFs能激活小G蛋白信号，也参与了多种发育过程，特别是细胞的极性发育。初步的突变体表型分析，ROP活性检测，蛋白互作检测结果显示RopGEFs可能参与到ABP1/TMK介导的生长素信号传导路径。我们推测RopGEFs可能被TMKs磷酸化然后激活膜内ROP信号。该项目以检测RopGEFs和TMKs的互作为中心，另外从遗传学上进行表型的比对与分析，全面解析RopGEFs调控铺板细胞形态发生的分子机制，进一步完善ABP1/TMK介导的生长素信号通路。