The role of bacterial extracellular RNAs in plant infections with Xylella

病原体的感染成功依赖于将毒力因子，即所谓的效应物，传递到宿主细胞中，以规避植物的免疫。自2013年以来，顶端木霉(XF)在欧洲作为一种细菌病原体出现，与橄榄树、杏仁树和柑橘树上的毁灭性流行病有关。由于缺乏III型系统及其分泌的效应器，XF抑制宿主免疫的机制仍未得到回答。胞外囊泡(EVS)是一种重要的细菌结构，与XF毒力相关。这个子项目将评估来自XF的EVS在宿主感染中的作用。我们最近在拟南芥中建立了XF感染，并观察到XF EV的免疫原性和免疫抑制活性。EVS上RNA结合蛋白和RNAs的检测表明，EVS可以运输细菌胞外RNA(ExRNA)物种。我们的目标是确定与XF病相关的EV RNA谱系，并解决EV RNA对植物免疫系统的调节作用。为了解决EV RNA物种和宿主靶标的签名是否在微生物物种中通用，我们将在RU5116中进行比较研究。受益于RU5116的研究，我们将探索RNA介导的针对XF的沉默。总而言之，这个子项目将导致对病原菌毒力，特别是对XF的致病机理的新的见解，并最终目的是识别新的病原体效应物和寄主靶标，当靶向时，将导致病原菌无毒力和植物抗性。

The infection success of pathogens depends on the delivery of virulence factors, so-called effectors, into host cells to circumvent plant immunity. Since 2013, Xylella fastidiosa (Xf) emerged as a bacterial pathogen in Europe associated with devastating epidemics in olive, almond and citrus trees. Lacking a Type III system and its secreted effectors, the mechanism used by Xf to suppress host immunity remain unanswered. Extracellular vesicles (EVs) are important bacterial structures, which have been associated with Xf virulence. This subproject will evaluate the role of EVs from Xf in host infection. We recently established Xf infection in Arabidopsis and observed both immunogenic and immune-suppressive activities of Xf EVs. Detection of RNA-binding proteins and RNAs at EVs suggests that EVs could transport bacterial extracellular RNA (exRNA) species. Our goal is to identify the EV RNA repertoire associated with Xf disease and to address the modulation of the plant’s immune system by EV RNAs. To address whether signatures of EV RNA species and host targets are common across microbial species, we will contribute to comparative studies within the RU5116. Benefitting from RU5116 research, we will explore RNA-mediated silencing against Xf. Together, this subproject will lead to new insights into the mechanisms contributing to pathogen virulence, in particular for Xf, and ultimately aims to identify novel pathogen effectors and host targets that, when targeted, will result in pathogen non-virulence and plant resistance.