磷脂酰肌醇-4-磷酸调控PIN2囊泡运输响应生长素信号的分子机制

磷脂酰肌醇磷酸盐（PIPs）在调控植物生长发育以及逆境响应中有重要作用。PIN2是转运生长素的重要膜蛋白。本项目拟研究PIPs对PIN2囊泡运输的调控及机理。以磷脂酰肌醇-4-磷酸激酶β（PI4Kβ）/磷脂酰肌醇-4-磷酸（PtdIns4P）为研究对象，比较观察野生型和pi4kβ1pi4kβ2质膜上PIN2的动态变化，研究PI4Kβs以及PtdIns4P对质膜PIN2的影响。利用酵母双杂交、分离荧光素酶系统和免疫共沉淀技术，筛选、鉴定与PI4Kβs/PtdIns4P互作的囊泡运输相关蛋白，研究PI4Kβs/PtdIns4P与相关蛋白互作对PIN2的质膜定位、丰度以及在反式高尔基体网络（TGN）与质膜之间运输的影响，从而阐明PtdIns4P介导生长素极性运输、根组织间浓度梯度建立的作用机制。研究结果对揭示磷脂调控植物激素（生长素）信号的机理有重要作用。

Phosphatidylinositol phosphates (PIPs) play critical roles in regulating plant growth, development as well as in the responses to abiotic and biotic stress, PIN2 is an important membrane associated carrier to transport auxin out of the cell. This project is dedicated to study how PIPs regulate membrane trafficking of PIN2 and uncover potential mechanisms. We will focus on phosphatidylinositol 4-OH kinase β (PI4Kβ) and phosphatidylinositol-4-phosphate (PtdIns4P), and compare dynamics of plasma membrane (PM) localized PIN2 between wild type and pi4kβ1pi4kβ2, and explore effects of PI4Kβs and PtdIns4P on PM localized PIN2. We will screen and identify target proteins that interact with PI4Kβs/PtdIns4P via yeast two hybrid, split luciferase, co-immunoprecipitation, and observe the influence of the interaction between PI4Kβs/PtdIns4P and the corresponding proteins on the localization and abundance of PIN2 at PM, as well as the trafficking between trans-Golgi network (TGN) and PM, and further uncover mechanisms for polarized transport of auxin and establishment of auxin gradient among organs of the root mediated by PtdIns4P. The results will help people understand how phospholipids regulate plant hormone (auxin) signaling transduction.