Functional characterization of the Phytophthora infestans effector Avr2

卵菌是深分支的真核生物，包括阿拉伯透明霜霉（Hyaloperonospora arabidopsidis），其是拟南芥上霜霉病的病原体，或引起马铃薯和番茄晚疫病的致病疫霉。计算机模拟分析预测，几种卵菌物种的基因组编码大量所谓的RXLR-dEER效应子，这些效应子被认为是操纵宿主细胞功能作为其感染策略的一部分。在拟南芥中使用基于细胞的系统，我们已经鉴定了致病疫霉RXLR dEER效应子Avr 2和BSU 1样磷酸酶之间的强相互作用。在拟南芥中过量表达Avr 2导致植物具有严重的矮化表型和异常的气孔密度。该表型与油菜素类固醇信号传导途径的缺陷一致，其中BSU 1样（BSL）磷酸酶作为正调节剂。该项目的主要目标将包括使用生物化学，分子生物学和反向遗传学方法来表征Avr 2在植物中的分子功能，重点是涉及BSL的油菜素类固醇依赖性反应。将研究后者在植物对病原体的抗性/易感性中的作用。该项目的研究结果将指导致病疫霉天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.