Barley endosomal MONENSIN SENSITIVITY1 is a target of the powdery mildew effector CSEP0162 and plays a role in plant immunity

Encasements formed around haustoria and biotrophic hyphae as well as hypersensitive reaction (HR) cell death are essential plant immune responses to filamentous pathogens. In this study we examine the components that may contribute to the absence of these responses in susceptible barley attacked by the powdery mildew fungus. We find that the effector CSEP0162 from this pathogen targets plant MONENSIN SENSITIVITY1 (MON1), which is important for the fusion of multivesicular bodies to their target membranes. Overexpression of CSEP0162 and silencing of barley MON1 both inhibit encasement formation. We find that the Arabidopsis ecotype No-0 has resistance to powdery mildew, and that this is partially dependent on MON1. Surprisingly, we find the MON1-dependent resistance in No-0 not only includes an encasement response, but also an effective HR. Similarly, silencing of MON1 in barley also blocks Mla3-mediated HR-based powdery mildew resistance. Our results indicate that MON1 is a vital plant ...围绕吸器（haustoria）与活体营养菌丝（biotrophic hyphae）形成的包被，以及过敏反应（hypersensitive reaction, HR）细胞死亡，是植物针对丝状病原菌的核心免疫应答。本研究针对受白粉病菌侵染的感病大麦中此类免疫应答缺失的潜在调控因子展开探究。研究发现，该病原菌分泌的效应蛋白CSEP0162可靶向植物莫能菌素敏感性1（MONENSIN SENSITIVITY1, MON1）——该蛋白对多泡体与其靶膜的融合过程至关重要。过表达CSEP0162或沉默大麦MON1基因，均会抑制包被的形成。本研究证实，拟南芥生态型No-0对白粉病菌具有抗性，且该抗性的产生部分依赖于MON1。令人意外的是，No-0中依赖MON1的抗性不仅包含包被应答，还伴随有效的HR细胞死亡。同样地，在大麦中沉默MON1基因，也会阻断Mla3介导的基于HR的白粉病菌抗性。本研究结果表明，MON1是植物...