Mechanisms and functions of SNARE protein-dependent and vesicle-mediated exocytosis in plant immune responses

对微生物病原体的细胞外免疫反应是植物中普遍存在的现象。我们结合遗传和生化研究揭示了至少存在三种分子机制限制微生物在外质体中的生长。这些包括囊泡介导的未知货物的胞吐，吲哚硫代葡萄糖苷衍生代谢物通过ABC转运体的运输，以及外泌体的生物发生/递送。在这个项目中，我们研究了囊泡介导的免疫反应，需要在质膜驻留的PEN1 syntaxin、接头蛋白SNAP33和囊泡驻留的VAMP721/722之间形成三重SNARE复合物。我们最近的观察表明，这种分泌途径在对细菌PAMPs的反应中被迅速激活，并有助于限制细菌的生长。这一发现和质谱技术的最新进展为植物根系分泌物的系统分析提供了基础。此外，我们将进行细胞生物学和生化实验，以更好地了解VAMP721/722膜室在植物防御反应中的性质和动力学。

Extracellular immune responses to microbial pathogens are a widespread phenomenon in plants. Our combined genetic and biochemical studies revealed the existence of at least three molecular mechanisms that restrict microbial growth in the apoplast. These include vesicle-mediated exocytosis of unknown cargo, transport of indole glucosinolate-derived metabolites through an ABC transporter, and the biogenesis/delivery of exosomes. In this project we study vesicle-mediated immune responses requiring ternary SNARE complex formation between plasma membraneresident PEN1 syntaxin, the adaptor protein SNAP33, and vesicle-resident VAMP721/722. Our recent observations show that this secretory pathway is rapidly activated in response to bacterial PAMPs and contributes to bacterial growth restriction. This and recent advances in mass spectrometry by which secreted molecules can be identified in root exudates, provide the basis for systematic analysis of cargo. In addition, we will perform cell biological and biochemical experiments to better understand the nature and dynamics of VAMP721/722 endomembrane compartments in plant defense responses.