Cross-kingdom RNA communication during smut fungal infection by Thecaphora thlaspeos

在感染过程中，病原体与其宿主沟通以抑制植物免疫系统并改变植物代谢。虽然在经典观点中，蛋白质效应物是主要的参与者，但最近已经变得明显的是，RNA也被交换并有助于跨王国通信。提出的递送机制是在细胞外囊泡（EV）中的转运，所述细胞外囊泡（EV）从病原体易位到宿主细胞以递送其货物。遗传上易处理的黑穗病真菌是研究EV介导的跨界RNA通讯的理想系统。在模式黑穗病真菌玉米黑粉菌中进行了关于EV中mRNA运输的开创性工作。在本论文中，我们主要研究了黑粉菌T. thlaspeos，这是我们最近建立的模式植物拟南芥（Arabidopsis thaliana）的一种遗传上易处理的病原体。我们将首先提供EV货物的清单，以随后解决跨王国RNAi和EV介导的mRNA转运对毒力的功能相关性。与U. maydis，T. thlaspeos保留了RNAi机制，因此在比较方法中，我们将确定mRNA和sRNA易位对感染的相对贡献。电动汽车的核心货物是什么？mRNA和sRNA靶向相同的植物过程吗？在RU 5116的exRNA通讯框架下，T. thlaspeos将呈现黑穗病真菌病原体，因为它能够使用sRNAs和mRNAs进行跨界通信。我们将比较RNA效应，特别是维管根病原体，互惠和病原体在常年感染。因此，我们将详细了解RNA效应子在植物-微生物相互作用中的功能作用。在未来，EV负载的分子机制的阐明将是重要的，以了解RNA是如何在病原体中的易位与翻译的目标。

During infections, pathogens communicate with their host to supress the plant immune system and modify plant metabolism. While in the classical view, protein effectors are the main player, recently it has become apparent that also RNAs are exchanged and contribute to cross-kingdom communication. A proposed delivery mechanism is the transport in extracellular vesicles (EVs) that translocate from the pathogen to the host cell to deliver their cargo. The genetically tractable smut fungi are ideal systems to study EV-mediated cross-kingdom RNA communication. Pioneering work on mRNA transport in EVs is carried out in the model smut fungus Ustilago maydis. In this proposal, we focus on cross-kingdom RNA communication in the Brassicaceae smut fungus T. thlaspeos, which we have recently established as a genetically tractable pathogen of the model plant Arabidopsis thaliana. We will first provide an inventory of the EV cargo to subsequently address the functional relevance of cross-kingdom RNAi and EV-mediated mRNA transport for virulence. In contrast to U. maydis, T. thlaspeos has retained the RNAi machinery, so that in a comparative approach, we will determine the relative contribution of mRNA and sRNA translocation to infection. What is the core cargo of EVs? Do mRNAs and sRNA target the same plant processes? In the frame of the RU5116, exRNA communication, T. thlaspeos will present the smut fungal pathogens, since it is able to use both sRNAs and mRNAs for cross-kingdom communication. We will compare RNA effectors in particular to vascular root pathogens, mutualists and pathogens during perennial infections. Thereby, we will gain detailed insight into the functional role of RNA effectors in plant-microbe interactions. In the future, elucidation of the molecular mechanisms of EV loading will be important to understand how RNAs are targeted for translocation vs. translation in the pathogen.