晚疫病菌寄主细胞核定位效应蛋白PITG_20303的毒性作用机理

晚疫病菌通过分泌效应蛋白促进其对寄主的侵染。PITG_20303是晚疫病菌保守效应蛋白AVRblb2的毒性变异类型之一，逃避了抗病蛋白Rpi-Blb2的识别。该效应蛋白定位于植物细胞核，具有毒性功能，但作用机制尚不清楚。实验室前期通过免疫共沉淀及蛋白质谱分析鉴定到本氏烟草NbbZIP53与 PITG_20303互作，系统发育分析表明马铃薯中存在4个直系StbZIP53同源蛋白。本项目拟通过免疫共沉淀、酵母双杂交和双分子荧光互补技术，验证PITG_20303与StbZIP53的互作；通过分析其对靶标的亚细胞定位、蛋白稳定性、蛋白二聚体等的调控，揭示其对寄主靶标的调控机理；通过StbZIP53的沉默、过表达，明确其抗、感晚疫病的功能；通过转录组测序结合染色质免疫沉淀，明确其对寄主抗、感晚疫病相关基因的调控。综合以上结果，期望揭示PITG_20303通过寄主靶标StbZIP53的毒性作用机理。

Phytophthora infestans secretes effectors to promote host colonization. PITG_20303 belongs to the virulence variants of AVRblb2, a conserved effector family from P. infestans, and it evades recognition by the corresponding R gene Rpi-Blb2. Previous report shows that PITG_20303 is a virulence factor localized mainly in the host nucleus. However, the virulence mechanisms of PITG_20303 are poorly understood. Previously, by protein immunoprecipitation followed by mass spectrometry assays we have identified NbbZIP53 as a putative host target protein of PITG_20303, and have confirmed their interaction. By phylogenetic analysis we have identified 4 potato orthologs of NbbZIP53. In this project, we plan to use co-immunoprecipitation, yeast two hybrid and bifluorescence complementation assays to study the interaction of PITG_20303 and potato homolog protiens StbZIP53; to investigate the co-localization of PITG_20303 with StbZIP53 and the influence of PITG_20303 on StbZIP53’s stability and homodimerization in order to reveal the mechanisms underlining PITG_20303’s modulation of StbZIP53; to generate transgenic potato lines that silenced or overexpressed with StbZIP53 gene to investigate its role in plant defence against P. infestans; and to investigate underlying mechanisms of StbZIP53 in resistance or susceptibility to P. infestans by identification of StbZIP53-regulated genes through transcriptome sequencing and chromosome immunoprecipitation. Taken together, we expect to understand how PITG_20303 modulates its host target StbZIP53 to regulate resistance or susceptibility of the host plant to potato late blight.