The Molecular Mechanism Of Phosphatidylinositol-Specific Phospholipase C(PI-PLC) On The Effect Of Plant Thermotolerance

The environmental temperature above the normal growth temperature is considered as heat stress or heat shock for the sessile plants.Heat and heat-related drought or other stress lead to a great loss in agriculture all over the world.Therefore,it is imperative to understand how plants perceive heat and how to improve thermotolerance in plants.Many signaling pathways are believed to be involved in heat stress responses,e.g.heat stress could trigger rapid[Ca2+]increase in cytopiasm.It is widely accepted that two pathways could induce[Ca2+]burst in cytoplasm.One is that extracellular Ca2+ enters the cytoplasm tuough Ca2+ channel located in plasma membrane,the other is that endomembrane calcium pool release Ca2+ by Ca2+ ion channel through PLC/IP3 pathway.The former pathway has been reported in moss and Arabidopsis.Only that heat shock cou]d activate PI-PLC is reported through the later pathway.Former research in our lab had proven that heat shock could induce rapid IP3 concentration increase which could be blocked by PLC specific inhibitor U73122.This demonstrated PLC/IP3 system may contribute to plant heat stress response.However,genetic data are needed to support these findings.Recenty,Dr.Shuzhi Zheng 's work,using AtPLC9 T-DNA insertion lines,complement plants and overexpression lines,indicated AtPLC9 may play important role in early heat stress response.I participated in Dr.Shuzhi Zheng's work,and finish the expression pattern analysis and subcellular location of AtPLC9.IP3 content and the intercellular[Ca2+]quantification after heat shock.and so on.Dr Shuzhi Zheng and I discovered that AtPLC3 as well as AtPLC9 may contribute to heat tolerance in Arabidopsis.atplc3 exhibited reduced thermotolerance after heat shock.We also gained atplc3 atplc9 plants.The heat tolerance reduction in double mutant seemed more obvious compared to single mutants.To determine the substrate of PLC,we performed expression and purification of PLC9 protein in vitro.We found suitable induction conditions and get large mount of PLC9-MBP fusion protein in cytoplasm.Then we purified PLC9-MBP though affinity chromatography.Using radical labeled-PIP2 we explored the enzymatic activity of PLC9-MBP.Since AtPLC9 contributes to heat tolerance in Arabidopsis.and we ask whether this gene also has function in rice.We transformed AtPLC9 to Chang You]rice widely planted in south of China.By optimizing the callus induction and transformation conditions,we successfully got the transgenic plants.