水稻OsMKK1-OsMPK2级联调控抗病反应的方式与机制

There is growing body of evidences suggesting that mitogen-activated protein kinase (MAPK) signaling plays critical roles in plant defense responses. However, molecular mechanism underlying the regulation of plant innate immunity by MAPKs is still not well understood. Furthermore, knowledge of the function of plant MAPKs comes mainly from studies on Arabidopsis and tobacco. Thus, current understanding of the MAPKs function in monocots is still preliminary. Recently we found that rice MAP kinase kinase OsMKK1 interacts with MAP kinase OsMPK2, and the rice mkk1 and mpk2 mutants showed similar morphological phenotypes and compromised resistance to bacterial blight, suggesting that the two kinases function in the same signaling cascade. The proposed study will focus on the following questions: 1) How does OsMKK1-OsMPK2 cascade regulate rice innate immunity; 2) What are the downstream targets of the OsMKK1-MPK2 cascade and their function in rice defense responses. The proposed research will lead to new insights into the regulation of defense response by MAP kinase cascade in monocots and possibly new monocot-specific components and mechanisms of MAPK signaling. The ultimate goal of these studies is to further reveal regulatory mechanisms of rice-pathogen interactions, meanwhile to provide new strategies and targets for plant disease resistance improvement.

越来越多的证据表明有丝分裂原活化蛋白激酶（MAPK）在植物抗病防卫反应中起着重要调控作用。但目前对植物MAPK调控抗病免疫反应机制的了解非常有限，且研究结果主要来自拟南芥和烟草，对禾本科作物MAPK功能的了解则更加匮乏。在前期的工作中，我们发现OsMKK1与OsMPK2蛋白相互作用，水稻mkk1和mpk2突变体具有相似的形态并都表现出对白叶枯病菌抗病性的减弱。这些结果暗示OsMKK1与OsMPK2极可能在同一抗病信号转导途径上起作用。本课题将深入研究水稻OsMKK1-OsMPK2级联调控抗病免疫的具体方式以及OsMKK1-OsMPK2级联的底物蛋白及其作用机理。该工作的开展将加深我们对单子叶植物MAPK级联调控抗病免疫机理的了解，并可能发现禾本科植物特异的MAPK调控抗病反应的组分和机制。研究结果将深入阐释水稻-病原微生物互作调控机制，同时为水稻抗病性的改良提供新的策略或靶标。

有丝分裂原活化蛋白激酶（MAPK）在先天免疫中发挥着至关重要的作用。免疫系统识别外界病原后，通过MAPK信号传导级联激发防卫基因的表达。越来越多的证据表明，植物MAPK调控植物抗病防卫反应。但目前对植物中MAPK调控抗病免疫机制的了解还非常有限，且研究结果主要来自拟南芥和烟草，对禾本科作物MAPK功能的了解则更加匮乏。我们从水稻OsMKK1和OsMPK2在酵母中互作及osmkk1和osmpk2突变体表型相似并表现出对白叶枯病菌抗病性减弱入手，运用遗传学、细胞生物学、生物化学等方法系统研究了OsMKK1与OsMPK2的遗传和生化关系和OsMKK1-OsMPK2级联调控抗病免疫的方式及其分子机制。取得的主要成果如下：.1）鉴定了水稻中一个参与抗病的MAPK蛋白激酶级联；.2）阐明了OsMKK1-OsMPK2级联调控抗病免疫的具体过程，加深了对MAPK蛋白激酶参与植物防卫反应方式的了解；.3）建立了一个新型的鉴定MAPK底物的方法，并得到了成功应用；.4）鉴定获得OsMPK2蛋白激酶的底物蛋白17个，并对它们在抗病反应中的功能进行了检测，为深入阐明OsMPK2级联调控水稻抗病反应的分子机制奠定了重要基础。 . 综合分析项目所得主要研究成果，我们鉴定出调控水稻PTI反应的一条较为完整的MAPK信号级联，并基本阐明其作用的分子机制。研究结果加深了我们对单子叶植物MAPK级联调控抗病免疫机理的了解，为深入阐释植物-病原物互作调控机制和水稻抗病性的改良提供新的策略或靶标。