WRKY77正调控茉莉酸介导的水稻抗病性研究

Expression levels of rice WRKY77 was induced by jasmonate treatment and inoculation of rice blast fungus Magnaporthe oryzae in a race-specific manner. Accumulation of JA and its analogs was increased in WRKY77 overexpression plants and decreased in its RNAi lines. Plant with increased WRKY77 expression exhibited enhanced resistance to M. oryzae, suggesting that WRKY77 is a positive regulator against the fungal pathogen. In this project, we will try to know how WRKY77 functions in the JA-mediated defense pathway of rice using its knock-out and overexpressing plants. We will figure out the target genes of WRKY77 and its interacting components by ChIP-seq, RNA-seq, yeast-two hybrid, immune coprecipitation, and so on methods, and select 1-2 unique genes for further studies. Also, we will analyze phosphorylation status of WRKY77 in response to JA treatment and pathogen infection and effects of WRKY77 phosphorylation on its biochemical functions and stability. The goal of this study is to figure out how WRKY77 functions in JA-mediated in the rice innate immunity.

水稻WRKY77受茉莉酸和稻瘟菌诱导，且具有小种特异性。超表达WRKY77增加了茉莉酸的积累和提高了对稻瘟菌的抗性，而RNAi干涉植株表现相反，说明WRKY77是水稻抗病的正调控因子。本项目将利用WRKY77敲除突变体等材料分析该基因对茉莉酸和水稻抗病信号途径的影响；通过ChIP-seq、RNA-seq、酵母双杂交和免疫共沉淀等方法获得WRKY77的靶标基因和互作蛋白，并挑选1-2个新基因进行后续研究；分析茉莉酸和稻瘟菌处理对WRKY77磷酸化修饰的影响以及磷酸化对WRKY77蛋白功能的影响。研究对明确WRKY77在茉莉酸介导的水稻抗病途径中的作用有意义。

研究结果表明OsWRKY77(OsWRKY7)受茉莉酸、PAMPs及病原菌诱导表达。促分裂原活化蛋白激酶活化的OsWRKY77主要通过茉莉酸信号途径来提高水稻的抗病性，正调控茉莉酸合成途径的基因OsAOS2和抗病防卫相关基因OsPR1b等的表达；同时OsWRKY77作用在OsWRKY89的上游，调控水稻柠檬烯合成酶基因OsTPS19的表达。超表达OsWRKY77的水稻增加了激素JA/JA-Ile、植保素樱花素等化合物的积累和对病原菌的抗性。OsWRKY77作用在OsCERK1受体激酶和OsMPK5激酶下游，通过磷酸化修饰增强其与W-盒的结合活性。OsJAZ5、OsJAZ9能与OsWRKY77互作、并增强其与W-盒的结合活性；OsWRKY77蛋白的磷酸化修饰能显著减弱这种互作关系。osmpk5突变体增加了对稻瘟病菌的敏感性，减弱了OsWRKY77靶标基因的诱导表达及相关化合物的积累。受该项目资助，已发表论文2篇，申请转基因中试1项。研究结果为解析水稻抗病机制、改良作物抗性提供了基础。