橡胶树白粉病菌Y/F/WxC效应蛋白功能分析

Powdery mildew is one of the most important rubber tree diseases, caused by obligate biotroph fungal Oidium heveae whose molecular mechanism of the pathogen is not clear. According to the genome and transcriptome of O. heveae which had been sequenced by former research work in our Lab, we screening to 233 Candidate Secreted Effector Proteins (CSEPs), including 106 Y/F/WxC effector proteins. CSEPs presumably represent the weapons of powdery mildews for pathogenesis, and no significant numbers of such Y/F/WxC effector proteins were identified from genome and EST sequences from either fungi (except powdery mildew). In this study, genomics, transcriptomics, bioinformatics and cytological methods are adopted. By compatible and incompatible interaction between O. heveae and disease-resistant or sensitive rubber tree lines,and Arabidopsis thaliana susceptible mutant, the relationship of Y/F/WxC CSEP and infection pathogenesis of O. heveae in host will be built; in the meantime, further identifying the function of 3-5 Y/F/WxC effector proteins by transient expression assay in tobacco, yeast-two hybrid (Y2H) and GST Pull-Down. These results will reveal the expression patterns of genes which encoding the Y/F/WxC effector proteins in O. heveae during infection process, described the role of Y/F/WxC effector proteins play in the process of infection and the function in the long-term evolution between the interaction of O. heveae and host. It will provide new theory for the development of rubber tree powdery mildew control strategies and biological evolution.

白粉病是橡胶树重要病害之一，由专性寄生菌Oidium heveae引起，其分子致病机理尚不清楚。我们已完成该病菌基因组和转录组测序，筛选到233个候选效应蛋白(CSEP)，其中Y/F/WxC效应蛋白106个。CSEP是O. heveae侵染寄主过程中的重要武器，Y/F/WxC是白粉菌CSEP特有保守基序。本研究采用基因组学、转录组学、生物信息学以及细胞学等方法，通过O. heveae与橡胶树抗感品系及拟南芥的亲和/非亲和互作，建立Y/F/WxC效应蛋白与侵染结构发育过程的对应关系，通过烟草瞬时表达系统，结合酵母双杂交、GST Pull-Down等技术鉴定3-5个Y/F/WxC效应蛋白功能，揭示病原侵入过程中Y/F/WxC效应蛋白表达模式，阐述关键Y/F/WxC效应蛋白在白粉病菌侵染寄主过程中的角色及其在白粉病菌与寄主长期进化中的作用，为制定橡胶树白粉病防控策略以及生物进化提供新的理论依据。

橡胶树白粉病是橡胶树重要叶部病害之一，由专性寄生菌Erysiphe quercicola引起，其分子致病机理尚不清楚。病原物通过分泌效应蛋白与寄主植物建立亲和互作，本研究完成了橡胶树白粉菌基因组和转录组的测序，并对其效应蛋白（经典泌出型和非经典泌出型）进行预测。在此基础上挑选10个在侵染阶段高表达的假定效应蛋白，通过农杆菌介导的烟草瞬时表达技术进行初步功能筛选，最终明确2个假定的非经典泌出型效应蛋白EqCmu和EqPDT能够促进辣椒疫霉的侵染。进一步通过酶活验证、系统发育分析、基因表达分析、酵母同源基因的敲除及互补验证、亚细胞定位和农杆菌介导的烟草瞬时表达技术对EqCmu和EqPDT的分子作用机制进行研究，最终明确了EqCmu和EqPDT可能不仅能够在真菌细胞质中行使合成芳香氨基酸的功能，也能够通过其酶活性作用于植物细胞质苯丙酮酸盐途径，抑制植物的SA合成，从而促进病原菌的侵染。