晚疫病菌效应子Pi22798靶向马铃薯StKNOX3调控晚疫病抗性免疫应答机制解析

马铃薯对保障我国粮食安全具有重要意义。晚疫病是马铃薯最严重病害，栽培品种抗性很容易被快速进化的晚疫病菌克服，易于爆发成灾。晚疫病菌侵染马铃薯时会分泌效应子进入寄主细胞，与作用靶标互作、从多个层面抑制马铃薯免疫反应。申请者前期研究发现晚疫病菌 “核心” 效应子Pi22798靶向马铃薯 DNA 结合蛋白 StKNOX3，StKNOX3 则与组蛋白单泛素化蛋白StHUB互作。预示Pi22798靶向StKNOX3促进其与特异DNA序列结合，并招募StHUB来修饰组蛋白H2B，从染色体水平通过调控抗性相关基因的表达来抑制免疫应答。本项目拟从Pi22798-StKNOX3-StHUB分子互作方面深入解析Pi22798如何通过靶向StKNOX3精细调控晚疫病抗性的机制。研究将揭示晚疫病菌效应子调控寄主抗性的一种新模式，拓宽和丰富晚疫病菌致病与寄主抗病机制的认识，为有效利用寄主免疫机制来改良马铃薯晚疫病抗性提供理论和实践依据。

Potato plays very import role in agriculture and food security in China. Late blight caused by Phytophthora infestans is the devastative disease of potato in the world. Resistance cultivars, used in potato production, are easily overcome by the quickly evolving aggressive new strains. P. infestans secreted and delivered number of effectors inside host cell where they targeted to various proteins to modulate and manipulate immune responses to promote disease. In previous research, we found that a core effector Pi22798 targeted with the potato DNA binding protein StKNOX3, while StKNOX3 interacts with StHUB which could monoubiquitinate histone H2B. Hypothesis that effector Pi22798 targeted to StKNOX3, which promotes StKNOX3 binding to specific region of genome DNA. After that，StKNOX3 recruits StHUB protein and then monoubiquitinates histone H2B to regulate disease related gene expression at transcriptional level. In this proposal, we will focus on the Pi22798-StKNOX3-StHUB molecular interactions and aimed to dissect the molecular mechanism of how P. infestans core effector Pi22798 manipulates potato late blight resistance by targeting the DNA binding protein StKNOX3. The project will uncover a new model of how P. infestans manipulates host immunity using effector as weapon. Present research will enrich and expand our understanding on how P. infestans subverts host innate immunity, which will provide us the theoretical bases and novel practical methods to improve potato late blight resistance.