植物病原真菌抑制几丁质触发植物免疫反应的策略

Strategies of plant pathogenic fungi to inhibit chitin-triggered plant immune responses

几丁质是真菌细胞壁的重要成分,其晶体结构使真菌细胞壁具有一定的强度和硬度,对植物病原真菌侵染结构和侵染菌丝的形成具有重要作用。在植物与真菌互作过程中,植物分泌的几丁质酶可以降解真菌的几丁质产生几丁质寡糖,几丁质寡糖作为一种病原相关分子模式(PAMP),能够被植物细胞膜上的几丁质受体识别进而触发植物免疫反应。植物病原真菌为了成功侵染植物进化出了多种策略抑制几丁质触发的植物免疫反应,具体而言,植物病原真菌分泌大量的效应蛋白、多糖或几丁质脱乙酰化酶、几丁质酶、蛋白酶等效应子抑制植物的免疫反应。这些效应子被分泌到植物细胞质外体或细胞内部破坏植物免疫系统,促进病原真菌在植物细胞中获取营养物质以供其定殖和生长发育。本文综述了植物识别几丁质的分子机制以及植物病原真菌抑制几丁质触发植物免疫反应的主要策略,并对今后的研究前景进行了展望。

Chitin is an important component of fungal cell wall.It imparts strength and rigidity to fungal cell wall due to its crystalline nature.Chitin plays an important role in infection-related morphogenesis of phytopatho-genic fungi,such as the infection structure and the infection hyphae.During the interaction between plants and plant pathogenic fungi,chitinases secreted by plants can degrade chitin to chitin oligomers.As a pathogen-asso-ciated molecular pattern(PAMP),chitin oligomer can be recognized by the membrane-located chitin receptors to stimulate plant immune responses.To successfully infect plants,plant pathogenic fungi have evolved a variety of strategies to inhibit the chitin-triggered plant immunity responses.Specifically,plant pathogenic fungi secrete many proteins such as effector proteins,polysaccharides or chitin deacetylases,chitinases and proteases to inhibit the plant defense responses.These proteins are secreted into the apoplast or inside the cell to destroy the plant immune system,which promotes the nutrient acquisition,colonization,growth,and development of the patho-genic fungi.This review summarizes the molecular mechanism of chitin recognition in plants and the main strate-gies to inhibit chitin-triggered plant immune responses of plant pathogenic fungi.We also discuss future research trends in this field.