水稻叶片中ABA诱导H2O2产生活化OsDMI3的机理研究

It was shown that the activation of rice Ca2+/calmodulin-dependent protein kinase (OsDMI3) by abscisic acid (ABA) is dependent on Ca2+,CaM and H2O2. However, the mechanisms of ABA-induced activation of OsDMI3 by H2O2 remain to be determined. In this project, based on our pervious studies, we intend to identify the mechanisms of H2O2- depressed interaction between OsPP45 and OsDMI3. Meanwhile,we shall elucidate the question whether H2O2 could directly activate OsDMI3. In addtion, we shall evaluate the roles of H2O2-induced Ca2+ and CaM in the processes of OsDMI3 activation by ABA. Further, we shall dissect how Ca2+/CaM activate OsDMI3 released by OsPP45 inhibition. By the reasearch of these aspects, the project will reveal the mechanism of ABA-induced activation of OsDMI3 by H2O2. This project is not only helpful to our understanding for the function of CCaMK under stress conditions, but also has an important significance for improvement of crop stress resistance by using molecular biology manipulation.

申请人先前的研究显示，ABA能够诱导水稻叶片OsDMI3活化，且H2O2、Ca2+以及CaM是必需的。然而，ABA诱导H2O2产生活化OsDMI3的机理尚有待阐明。本项目拟在前期工作的基础上，一方面调查H2O2抑制OsPP45与OsDMI3互作的机制，同时明确H2O2能否直接活化OsDMI3；另一方面调查H2O2调控的Ca2+、CaM在ABA诱导的OsDMI3活化中的作用；最后研究Ca2+/CaM活化从OsPP45抑制中释放的OsDMI3的机理，从而阐明ABA诱导OsDMI3活化的分子机制。这一研究的开展有助于人们对CCaMK参与植物抗逆反应作用机制的认识，为利用分子生物学手段提高作物的耐逆性提供重要的理论基础。

本项目在前期工作的基础上调查了水稻叶片中ABA产生H2O2活化OsDMI3的机理研究，主要研究结果如下：.（1）调查了水稻叶片中ABA通过H2O2抑制OsDMI3与OsPP45的互作的机制。前期研究发现水稻叶片中OsDMI3与OsPP45相互作用。本项目发现ABA通过产生H2O2氧化OsPP45的Cys350和Cys428位点使其形成分子间二聚体，进而抑制OsPP45的活性来解除OsDMI3与OsPP45的相互作用。同时明确了ABA和H2O2都不能直接活OsDMI3。.（2）调查了H2O2调控的Ca2+、CaM在ABA诱导的OsDMI3活化中的作用。调查发现OsPP45作用于OsDMI3的CaM结合区域，抑制OsDMI3与CaM结合而抑制其活性。.（3）研究了Ca2+/CaM活化从OsPP45抑制中释放的OsDMI3的机理。明确了ABA能通过抑制OsPP45的活性释放OsDMI3，使OsDMI3的T263位点自磷酸化。自磷酸化的OsDMI3结合H2O2活化的CaM从而磷酸化下游底物，传递ABA反应。.（4）调查了水稻叶片中OsLEA5在增强水稻耐逆性中的作用。.（5）分析了水稻叶片中OsMPK1作用BIP130上游调控ABA诱导的抗氧化途径的机理。.本项目已在Plant Cell、Plant Cell Physiol等刊物上发表论文3篇，另有1篇论文待发表。这些研究结果不仅加深了我们对ABA信号转导机理的认识，而且对于进一步利用分子手段提高农作物的抗逆性具有重要的指导意义。