Zhang Xiaoxiao, Yang Yuwen, Zhao Mei, Yang Linlin, Jiang Jie, Walcott Ron, Yang Shanshan, Zhao Tingchang
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
Department of Plant Pathology, University of Georgia, Athens, GA, United States.
Front Plant Sci. 2020 Nov 20;11:579218. doi: 10.3389/fpls.2020.579218. eCollection 2020.
is the causal agent of bacterial fruit blotch (BFB), and BFB poses a threat to global watermelon production. Despite its economic importance, the molecular mechanisms underlying pathogenicity and virulence are not well understood, particularly with regard to its type III secreted effectors. We identify a new effector, AopP, in and confirm its secretion and translocation. AopP suppresses reactive oxygen species burst and salicylic acid (SA) content and significantly contributes to virulence. Interestingly, AopP interacts with a watermelon transcription factor, ClWRKY6, and . ClWRKY6 shows typical nuclear localization, and AopP and ClWRKY6 co-localize in the nucleus. infection, SA, and the pathogen-associated molecular pattern flg22 promote ClWRKY6 production, suggesting that ClWRKY6 is involved in plant immunity and SA signaling. Furthermore, ClWRKY6 positively regulates PTI and SA production when expressed in . Importantly, AopP reduces mRNA and ClWRKY6 protein levels, suggesting that AopP suppresses plant immunity by targeting ClWRKY6. In summary, we identify a novel effector associated with the virulence mechanism of , which interacts with the transcription factor of the natural host, watermelon. The findings of this study provide insights into the mechanisms of watermelon immune responses and may facilitate molecular breeding for bacterial fruit blotch resistance.
是细菌性果斑病（BFB）的致病因子，BFB对全球西瓜生产构成威胁。尽管其具有经济重要性，但其致病性和毒力的分子机制尚未完全了解，特别是关于其三型分泌效应子。我们在中鉴定出一种新的效应子AopP，并证实了其分泌和转运。AopP抑制活性氧爆发和水杨酸（SA）含量，并对毒力有显著贡献。有趣的是，AopP与西瓜转录因子ClWRKY6相互作用，并且。ClWRKY6显示出典型的核定位，AopP和ClWRKY6在细胞核中共定位。感染、SA和病原体相关分子模式flg22促进ClWRKY6的产生，表明ClWRKY6参与植物免疫和SA信号传导。此外，ClWRKY6在中表达时正向调节PTI和SA的产生。重要的是，AopP降低mRNA和ClWRKY6蛋白水平，表明AopP通过靶向ClWRKY6抑制植物免疫。总之，我们鉴定出一种与的毒力机制相关的新型效应子，它与天然寄主西瓜的转录因子相互作用。本研究结果为西瓜免疫反应机制提供了见解，并可能有助于细菌性果斑病抗性的分子育种。
