病原菌保守性特征分子及其介导的植物抗病性

Pathogen conservation molecules and PAMP-triggered innate immunity in plants

摘要:

每种病原菌都有一些保守的特征性分子, 也称病原菌相关分子模式(PAMPs)。植物细胞表面的模式识别受体PRRs通过识别病原菌的PAMPs而激发免疫反应(PTI)。目前, 已发现多种PRRs/PAMPs的识别模式, 如拟南芥FLS2识别细菌鞭毛蛋白、拟南芥EFR识别细菌延长因子Tu (EF-Tu)、水稻CEBiP/CERK1识别真菌几丁质、水稻抗病蛋白XA21识别白叶枯病菌的硫化蛋白Ax21等。这些识别模式都能激发植物的基础免疫反应以抵抗病原菌的侵染。但是病原菌为了成功侵染寄主植物, 也进化出一些致病机制, 例如向植物细胞中注入毒性效应蛋白阻断PTI途径, 或者产生一种“自我伪装”机制以逃避PRRs的识别。因此, 研究者们根据PAMPs的结构特性对PRRs重新改造, 以期使植物获得持久、广谱和高效的抗性。综述目前已知的PAMPs分子类型、PRRs/PAMPs的识别机制及改造后的新型PRRs, 并分析PTI研究中存在的问题及其发展前景。

Abstract:

Pathogen associated molecular patterns (PAMPs) recognized by host cell surface localized pattern-recognition receptors (PRRs) are pathogen conservation molecules. So far, a few pairs of characterized PRR/PAMP in plants provided useful models to study the specificity of ligand-binding and likely activation mechanisms. For example, recognition models of FLS2-flagellin, EFR-Tu (EF-Tu), CEBiP/CERK1-chitin and XA21-Ax21 have been extensively studied. The perception between PRR and PAMP triggers immune response (PTI) to resist pathogens. However, to successfully grow and proliferate on their hosts, virulent pathogens had to override the PTI, for which, these pathogens evolved a variety of strategies, such as injecting effector proteins into the plant cell or sequestering their PAMPs. Based on the knowledge on the interaction of PRR-PAMP, researchers are trying to engineer PRRs ( chimeras of PRRs) to develop new strategies in molecular breeding for achieving durability and a broad-spectrum disease resistance. We reviewed the recent findings about recognitions of PRRs-PAMPs, the engineered PRRs, and discussed the future prospects and several issues in researches on PTI.