分泌蛋白SsSVP2调控核盘菌致病力的分子机制研究

Sclerotinia sclerotiorum is a typical necrotrophic fungus, which causes Sclerotinia stem rot (SSR) in many crops and is one of the important diseases in rapeseed production. Oxalic acid and hydrolases secreted by S. sclerotiorum are considered as the main pathogenicity factors, also the important role played by the secreted proteins in the pathogenicity of S. sclerotiorum is paid more attention. Previously analysis of genome, transcriptome, and secreted proteome of S. sclerotiorum, we characterized a hypothetical secreted protein SsSVP2 (sscle_04g033140), that gene deletion mutants showed no obvious changes on mycelia growth, colony morphology, and sclerotia development. While the virulence on the rapeseed decreased by more than 30%, indicating that SsSVP2 is involved in the pathogenicity of S. sclerotiorum, SsSVP2 may be a potential effector-like protein. This project is intended to clarify the subcellular localization of SsSVP2 and its effect on host plant, identify SsSVP2-interacting proteins. Further, we will clarify the site or region of SsSVP2 which associated with SsSVP2-interacting proteins, and reveal the biological function of the interaction between SsSVP2 and SsSVP2-interacting proteins. Finally the molecular mechanism of SsSVP2 in the pathogenicity of S. sclerotiorum will be elucidated. These results will provide an important information for understanding the complex pathogenicity of S. sclerotiorum and disease resistance breeding against SSR.

核盘菌是典型的死体营养型病原真菌，引起多种作物的菌核病，是油菜生产中的重要病害之一。核盘菌分泌的草酸和水解酶类被认为是主要的致病因子，但是分泌蛋白在核盘菌的致病过程中所发挥的重要作用越来越受到重视。申请者前期通过对核盘菌的基因组、转录组和分泌蛋白质组进行分析，筛选到一个假定的分泌蛋白SsSVP2（sscle_04g033140），基因缺失后不影响菌丝生长、菌落形态和菌核发育，但在油菜上的致病力下降30%以上，表明SsSVP2参与了核盘菌的致病过程，可能是一个潜在的类似效应子的蛋白。本项目拟在此基础上，明确SsSVP2在植物细胞中的定位以及对寄主植物细胞的影响，鉴定与SsSVP2互作的植物蛋白，确定SsSVP2参与互作的位点或区域，揭示SsSVP2与互作蛋白分子互作的生物学功能，以此解析SsSVP2在致病过程中的分子作用机制。研究结果将为阐明核盘菌复杂的致病机理和抗菌核病育种提供重要参考。

油菜菌核病是由死体营养型病原真菌核盘菌引起的，是油菜生产中的重要病害之一。核盘菌寄主范围广、危害多种重要作物，长期以来认为其分泌的草酸和水解酶类是主要的致病因子，已有研究表明分泌蛋白在核盘菌的致病过程中所发挥的重要作用已受到广泛关注。. 在SsSVP2与核盘菌致病力相关的工作基础上开展相关研究，明确了Sssvp2基因敲缺失导致核盘菌侵染垫形成数量减少和致病力下降，并与核盘菌的高渗胁迫相关。同时，明确了SsSVP2在植物细胞中的亚细胞定位，证实SsSVP2不能诱导植物细胞发生坏死和抑制植物细胞坏死，SsSVP2可能通过干扰寄主植物的免疫反应促进核盘菌的侵染。在核盘菌体内鉴定到一个调控SsSVP2表达的转录因子SsFZC1，解析了转录因子SsFZC1缺失后的生物学功能，证实转录因子SsFZC1与侵染垫形成、菌核发育密切相关，正调控某些分泌蛋白的表达，利用HIGS沉默Ssfzc1可以增强寄主植物的抗病性。. 本项目所取得研究成果，有助于深入解析核盘菌的致病机理，为菌核病抗性种质资源的创制提供理论依据。