大麦抗病蛋白MLA免疫复合体的组分鉴定及其介导免疫的机制研究

Plants utilize NB-LRR type resistance (R) proteins to detect avirulence effectors from invading pathogens and trigger isolate-specific immune responses. However, the mechanisms of effector recognition or downstream signaling triggered upon R protein activation are so far not well understood. The barley Mla locus encodes allelic NB-LRR type R proteins to mediate defense responses against the powdery mildew pathogen. Accumulating evidence shows that diverse proteins associate with the R protein MLA during barley-powdery mildew interactions, suggesting the presence of immune complexes involving MLA. In this study, we plan to elucidate composition of the MLA-containing immune complexes, and therefore explore how R proteins recognize effectors and mediate downstream immune responses. We will carry out investigations to: 1) identify components of the MLA-containing immune complexes, and tempo-spatial dynamics of the components, e.g. at difference stages of MLA activation and in different subcellular compartments; 2) analyze the immunity-related function of individual components identified in the immune complex; 3) analyze the evolutionary conservation of plant immunity between monocot and dicot, based on the core components of the immune complexes; 4) isolate and identify avirulence effectors secreted from barley powdery mildew fungi.

植物利用NB-LRR类型的抗病蛋白识别相应的病原菌无毒效应蛋白从而激发专化性抗病反应（ETI）。至今，抗病蛋白如何识别效应蛋白及激活后如何介导下游免疫反应的机制仍不甚清楚。大麦抗病基因座Mla编码多个NB-LRR类型的抗病蛋白抵御白粉病菌的侵染。越来越多的证据表明在大麦与大麦白粉菌互作过程中，抗病蛋白MLA与多种蛋白均有互作，MLA可能以免疫复合体的形式存在。本项目拟深入解析MLA免疫复合体的组成，进而揭示抗病蛋白被激活及引发下游免疫反应的机制。研究将包括以下几方面：鉴定MLA免疫复合体组分、分析其时空动态变化（例如MLA被激活前后、MLA不同亚细胞定位等）；研究MLA免疫复合体各组分介导免疫的分子机制；挖掘免疫复合体的核心组分，探讨单子叶与双子叶植物之间免疫机制进化的保守性；鉴定大麦白粉菌无毒效应蛋白。

植物利用NB-LRR类型的抗病蛋白识别相应的病原菌无毒效应蛋白从而激发专化性抗病反应（ETI）。至今，抗病蛋白如何识别效应蛋白及激活后如何介导下游免疫反应的机制仍不甚清楚。大麦抗病基因座Mla编码多个NB-LRR类型的抗病蛋白抵御白粉病菌的侵染。利用大麦与白粉菌互作体系为模式，本着解析大麦MLA免疫复合体的组成、探究其识别及激活机制的目的展开研究。执行期间鉴定到可能是大麦MLA免疫复合体组分的关键蛋白：分子伴侣HSP60以及调节植物能量平衡的关键蛋白SnRK1α。研究发现SnRK1α能磷酸化MLA10的S562位点，MLA10介导大麦对白粉菌的小种专化抗性依赖于其S562位点的磷酸化，而S562位点的磷酸化会导致MLA引发细胞死亡功能的丧失。上述结果为解析抗病蛋白识别病原菌并激活下游免疫反应的具体机制提供了重要信息。