寄主植物与病原菌免疫反应的分子遗传基础

近年来,大量的植物抗病基因和病原菌无毒基因被克隆,抗病基因和无毒基因的结构、功能及其互作关系的研究也取得重大进展。在植物中,由病原菌模式分子(pathogen-associated molecular patterns, PAMPs)引发的免疫反应(PAMP-triggered immunity, PTI)和由效应因子引发的免疫反应(effector-triggered immunity, ETI)是植物在长期进化过程中形成的两类抵抗病原物的机制。PTI反应主要通过细胞表面受体(patternrecognition receptors, PRRs)识别并结合PAMPs从而激活下游免疫反应,而在ETI反应中,则通过植物R基因(resistance gene,R)与病原菌无毒基因(avirulence gene, Avr)产物间的直接或间接相互作用来完成免疫反应。本文对植物PTI反应和ETI反应分别进行了概述,重点探讨了植物R基因与病原菌Avr基因之间的互作遗传机理,并对目前植物抗性分子遗传机制研究和抗病育种中的问题进行了探讨和展望。

Molecular genetic mechanisms of interaction between host plants and pathogens

In recent years, a great number of plant resistance(R) genes and pathogen avirulence(Avr) genes were identified. Exciting breakthroughs were also made on the structural and functional analysis of R proteins and Avr proteins, and the mechanistic interaction between them. Plants have evolved two layers of the immune system to cope with pathogens in the evolutionary processes, which are pathogen-associated molecular pattern(PAMP)-triggered immunity(PTI) and effector-triggered immunity(ETI). In PTI responses, conserved PAMPs are recognized by plant plasma membrane-localized pattern recognition receptors(PRRs) and disease resistance is activated. Furthermore, the ETI immune signaling is activated by the recognition of pathogen Avr proteins by the host R proteins, which usually results in hypersensitive responses at the infection site. In this review, we summarize the progresses on PTI and ETI, and discuss the genetic mechanism of the interaction between plant R gene and pathogen Avr gene in detail. We also envision the new challenges and propose the new strategies for the future investigations on plant resistance molecular breeding.