AtCHYR1/2在拟南芥种子萌发过程中响应葡萄糖信号的功能研究

Glucose regulates plant growth and development by controlling the expression of genes that involved in photosynthesis, biosynthesis and nutrient distribution. Although there are several glucose-responsive pathways in plant, the regulatory network is still largely unknown so far. Our previous research has demonstrated that AtCHYR1 functions in glucose inhibition of seed germination process, which encoded an ubiquitin E3 ligase in ABA-dependent drought response. Overexpression of AtCHYR1 improved sensitivity to high concentration glucose，while loss-function of AtCHYR1 compromised sensitivity to high concentration glucose. Mutant of AtCHYR1 homolog (AtCHYR2) show similar phenotypes. Therefore, these results suggest that AtCHYR1/2 response to glucose during seed germination as key factors. In this study, we will employ molecular genetics, biochemical and cellular biology approaches to characterize the function of AtCHYR1/2 in glucose-responsive pathways, and then elucidate the molecular regulatory mechanism of glucose signaling mediated by AtCHYR1/2 through finding the interaction factors via co-immunoprecipitation and proteomics approaches. In addition, we will analysis the location of AtCHYR1/2 in glucose-ABA cascade pathway to understand the mechanism underlying the interaction between glucose and ABA signaling. The result will further uncover the molecular mechanism of glucose signaling, and prove the networks between plant hormones interact with environmental factors.

葡萄糖通过调控参与光合作用、生物合成和营养分配等过程的基因表达调节植物生长发育过程。目前，其精细的调控网络并不是很清楚。前期工作发现，拟南芥中ABA依赖的干旱胁迫响应E3连接酶基因AtCHYR1参与葡萄糖抑制的种子萌发过程。该基因功能缺失突变体和过表达植株分别降低和增强了对高浓度葡萄糖的敏感性。同源基因AtCHYR2显示相类似的表型，表明AtCHYR1/2是种子萌发过程中响应葡萄糖信号的重要因子。本研究中我们拟采用分子遗传学、生化与细胞生物学等手段明确AtCHYR1/2在葡萄糖信号途径中的功能；通过免疫沉淀结合质谱技术筛选和鉴定它们的互作蛋白，深入解析AtCHYR1/2调控葡萄糖信号响应的分子机制；分析AtCHYR1/2基因在葡萄糖-ABA级联途径中的位置，加深对葡萄糖和ABA信号互作机制的认识。本研究将进一步揭示葡萄糖信号的分子机理，探明植物激素与环境因子之间的互作网络系统。

葡萄糖通过调控参与光合作用、生物合成和营养分配等过程的基因表达调节植物生长发育过程。目前，其精细的调控网络并不是很清楚。在本研究中，我们发现泛素E3连接酶AtCHYR1及其同源蛋白AtCHYR2是种子萌发过程中响应葡萄糖信号的调控因子，通过高浓度葡萄糖胁迫下对chyr1、chyr2、chyr1chyr2、35S:AtCHYR1、35S:AtCHYR2等植株在种子萌发和生长过程中的生理表型观察和生理指标测定，明确了AtCHYR1和AtCHYR2在植物葡萄糖信号途径中的功能，其中AtCHYR2调控高浓度葡萄糖抑制子叶转绿过程，而AtCHYR1调控高浓度葡萄糖抑制种子萌发到子叶展开过程。通过免疫沉淀结合质谱技术、酵母双杂交、烟草BiFC和Co-IP等技术，筛选并确定互作蛋白为蛋白磷酸酶PP2A的C1亚基和C2亚基，揭示AtCHYR1可能通过与蛋白磷酸酶PP2A相互作用而调控葡萄糖信号响应过程，进而推测AtCHYR1可能通过调控PP2A的蛋白磷酸酶活性进而影响SnRK1的磷酸化状态来调控葡萄糖信号通路。本项目为揭示植物糖信号传导的分子机理以及糖与ABA激素信号之间的网络互作机制具有理论意义，同时也可用于农作物的遗传育种，降低农作物种子在不良条件下的萌发,从植物糖信号角度为植物抗性改良提供新的有效途径。