Functional characterization of the Phytophthora infestans effector Avr2

卵菌是一类深分枝真核生物，包括引起拟南芥霜霉病的阿拉伯透明膜孢菌或引起马铃薯和番茄晚疫病的致病疫霉。在计算机分析中预测，几个卵菌物种的基因组编码了大量所谓的RXLR-鹿效应器，这些效应器被认为是操纵宿主细胞功能的感染策略的一部分。在拟南芥中，利用基于细胞的系统，我们已经鉴定出致病疫霉RXLR鹿类效应器Avr2和BSU1样磷酸酶之间存在强烈的相互作用。Avr2在拟南芥中的过表达导致植株出现严重的矮化表型和异常的气孔密度。这种表型与油菜素类固醇信号通路的缺陷相一致，在该通路中，BSU1样(BSL)磷酸酶起到正调节作用。该项目的主要目标将包括使用生化、分子生物学和反向遗传学方法来表征Planta中Avr2的分子功能，重点是与BSL相关的油菜素类固醇依赖反应。后者在植物对病原菌的抗性/敏感性中的作用将被研究。本项目的研究成果将指导致病疫霉自然寄主植物的基础研究。

Oomycetes are deep-branching eukaryotes that include Hyaloperonospora arabidopsidis, the causal agent of downy mildew on Arabidopsis thaliana, or Phytophthora infestans which causes potato and tomato late blight. In silico analysis predicted that the genome of several oomycete species encodes for a large number of so-called RXLR-dEER effectors that are assumed to manipulate host cellular functions as part of their infection strategy. Using a cell-based system in Arabidopsis we have identified a strong interaction between the P.infestans RXLR dEER effector Avr2 and BSU1-like phosphatases. Overexpression of Avr2 in Arabidopsis leads to plants having a severe dwarf phenotype and abnormal stomata density. The phenotype is consistent with a defect of the brassinosteroid signalling pathway in which BSU1-like (BSL) phosphatases act as positive regulators. The main objective of this project will consist to use biochemical, molecular biology and reverse genetic approaches to characterize the molecular function of Avr2 in Planta with focus on the brassinosteroid-dependent responses involving BSLs. The role of the latter in plant resistance/susceptibility to pathogens will be investigated. The results coming out from this project will guide fundamental research in the natural host plants of P.infestans.