在鉴定一个新的大豆疫霉无毒效应分子PsAvr3b的过程中，我们首次发现疫霉菌基因组存在一类独特的能够抑制植物免疫反应的含有RxLR-Nudix基序的效应分子家族。本项目将通过对测序的约30种疫霉菌和其它物种的Nudix序列进行系统的生物信息学分析，了解RxLR-Nudix类效应分子的分布、起源以及进化过程；通过植物体内表达效应分子，分析不同RxLR-Nudix类效应分子在抑制植物免疫反应中的作用；通过对疫霉菌中效应分子的基因沉默，研究其对疫霉菌致病性的作用；通过筛选效应分子在寄主细胞内的分子靶标，研究效应分子对靶标蛋白的修饰作用，分析它们如何与植物靶标结合、如何抑制植物抗病反应，并对其结构特征进行解析。研究结果将为认识疫霉菌如何通过效应分子抑制植物免疫提供新的知识，有助于从分子水平上认识植物对疫霉菌的抗性机制，为合理利用植物抗病性、通过基因工程改良植物对疫霉菌的抗病性提供理论指导。

In the identification of a new Avirulence effector PsAvr3b of Phytophthora sojae, we first discovered a unique class of RxLR effectors containing Nudix motif, which could suppress plant immunity, and only exist in Phytophthora genus. In this project, basing on the genomic sequences of more than 30 Phytophthora species and some other organisms, we will study the distrubution,origination, and evolution of this RxLR-Nudix effector family by bioinformatic analysis; testing their virulence function in inhibiting plant immunity by expressing effectors in plant tissue; elucidating their contribution of these effectors to the pathogenicity of different Phytophthora species by gene silencing; identification of their molecular targets in plant cell, and testing the modification of effectors to their target proteins, determining the protein structure of effectors, and elucidating the mechnism by which these effectors bind their targets and interfer with plant immunity. The results will provide new knowledge to understand how Phytophthora suppress plant immunity by RxLR effectors, help to understand the molecular mechnism of plant resistance to Phytophthora, and will provide theoretical guidance to the utilizaiton and modification of plant resistance to control Phytophthora plant disease.