水稻耐盐响应中磷脂酶C介导的磷酸肌醇平衡和钙信号

磷酸肌醇（PIs)是磷脂酰肌醇（PtdIns）及其磷酸化产物的总称。经典磷脂酶C（PI-PLC）水解PtdIns(4,5)P2，生成二酰甘油和肌醇1,4,5-三磷酸。与动物细胞不同，植物细胞PtdIns(4,5)P2含量远低于PtdIns4P。我们发现了一个盐敏感的、水稻PI-PLC基因突变体（osplc1），体外试验表明，OsPLC1对 PtdIns4P的活性远远大于对PtdIns（4,5）P2。我们将以OsPLC1为研究对象，利用荧光标记的PIs探针蛋白，在细胞和植株水平上探索PtdIns4P是否作为水稻PI-PLC底物的证据；分析盐响应过程中PI-PLC活性是否影响PtdIns4P和PtdIns(4,5)P2 平衡，以及此平衡变化对耐盐性的作用。研究PI-PLC及其水解产物是否、如何调控Ca2+ 信号。本研究有望揭示植物PI-PLC的特异性，并阐明其在水稻耐盐中的作用机理。

Phosphoinositides (PIs) refer collectively to a group of membrane lipids comprising phosphatidylinositol (PtdIns) and its phosphorylated counterparts. Classic PLC (PI-PLC) hydrolyzes PtdIns(4,5)P2 to generate diacylglycerol and inositol1,4,5-trisphosphate. In plant cells, however, the concentration of PtdIns(4,5)P2 is much lower than that of PtdIns4P. We have identified a rice osplc1 mutant which is sensitive to salt stress. The protein of OsPLC1 expressed in E. coli showed a greater activity toward to PtdIns4P than to PtdIns(4,5)P2. In this project, we plan to determine whether this PI-PLC hydrolyzes PtdIns4P in cells and in planta, using PIs sensors. We will investigate the effects of salt-induced PI-PLC activation on the balance between PtdIns4P and PtdIns(4,5)P2, and salt tolerance. Whether and how Ca2+ signals are affected by the PLC hydrolysis products will also be explored in this project. The research will promote the identification of plant unique PI-PLC, and its function in rice resistance to salt stress.