马铃薯晚疫病菌效应蛋白PexRD24与其寄主抗病相关基因的识别及应答机制研究

Potato late blight, is one of the most destructive oomycete diseases. The agent of Phytophthora infestans, secretes proteins called effector into the host cell. Those proteins suppress plant immunity as the important weapon and play critical role during the pathogen infecting. Based on the pre-exsiting research, an effector from P. infestans called PexRD24, strongly upregulated in potatoes and N. benthamiana suggesting that it is a｀core＇effector. A lot of experiments showed P. infestans effector PexRD24 needed isoforms of host protein phosphatase type 1c (PP1c) which interacts with RD24 to successfully develop P. infestans. This study aims to screen potato resources which were specifically recognized and resisted by RD24 gene through overexpressing RD24 in potato plants. Microarray data will be utilized to explore potato resistance genes associated with RD24. The response mechanisms between RD24 and resistant genes to RD24 will be analyzed by constructing RD24 mutant via the interaction KVTF motif between RD24 and PP1c. All these studies will provide strategy for preventing effector RD24 to help P.infestans to develop disease, providing important clues and theoretical basis about its recognition mechanisms between resistance genes and RD24，also providing genes source for getting RD24 resistant germplasm resources.

晚疫病为马铃薯第一大毁灭性卵菌病害，该病原菌即致病疫霉菌P. infestans在侵入寄主细胞的同时分泌效应蛋白，这类蛋白在晚疫病致病过程中发挥着关键作用，是其抑制植物免疫的最重要武器。前期研究发现PexRD24是一种重要的核心效应蛋白，超量表达后显著促进晚疫病菌侵染马铃薯和烟草，大量实验证明RD24必须利用与其寄主互作的靶标蛋白磷酸酶PP1c才能实现侵染。本项目拟通过在马铃薯上过量表达RD24，从马铃薯抗晚疫病种质资源中筛选与RD24特异性识别的抗病资源。结合基因表达谱芯片技术超量表达RD24基因，分析相关基因表达，挖掘与RD24相关抗病基因。基于RD24与PP1c互作位点KVTF基序构建RD24突变体，初步分析抗病基因与效应蛋白RD24的应答机制。本研究将为抑制RD24帮助晚疫病菌侵染寄主提供研究策略，为其抗病基因的识别机制提供重要线索和理论依据，为获得抗RD24种质资源提供基因来源。

晚疫病为马铃薯第一大毁灭性卵菌病害，其病原即致病疫霉菌P. infestans在侵入寄主细胞的同时分泌效应蛋白，这类蛋白在晚疫病致病过程中发挥关键作用。前期研究发现，致病疫霉菌的一个重要核心效应蛋白PexRD24，利用其寄主靶蛋白I型蛋白磷酸酶（PP1c）来促进晚疫病菌侵染。基于这一研究基础，本项目通过寻找特异性识别效应蛋白RD24的马铃薯抗性资源，初步分析了效应蛋白RD24的抗性基因对RD24的应答机制。目前已取得如下研究进展：（1）在马铃薯种质资源库内收集了80份马铃薯野生种和栽培种抗性种质资源，经接种鉴定，筛选获得了具有中抗及以上晚疫病抗性的种质资源20份。（2）利用农杆菌介导和PVX侵染表达系统，成功找到了对晚疫病具有最高级抗性且含有RD24抗性基因的野生种Solanum papita。（3）构建了RD24与PP1c关键互作位点KVxF突变体RD24mut，经PVX侵染系统表型检测，发现S. papita不能识别RD24mut，表明目标抗性基因与PP1c/RD24的互作及识别存在潜在关联性。（4）将抗病亲本S. papita与感病亲本进行杂交，成功构建了F1代马铃薯抗/感分离杂交群体。（5）利用R基因目标序列富集测序（Renseq）和图位克隆技术，快速将该抗性基因锁定至5号染色体的一定区段。本研究后续有望克隆一个新的马铃薯抗性基因，同时揭示RD24与R基因的识别机制，为马铃薯晚疫病科学高效防控提供理论和技术支撑。