Role of organelle dynamics and retrograde signaling during plant innate immunity

1项目概要 2该项目的重点是叶绿体作为产生免疫信号的核心参与者， 3.调节针对病原体感染的先天免疫应答所需的程序性细胞死亡（PCD）。 4虽然线粒体在哺乳动物PCD过程中起着核心作用，但新出现的证据表明，在植物中， 5叶绿体在执行限制病原体传播的局部PCD中具有关键功能。叶绿体 除了参与免疫信号的产生，如活性氧（ROS）和免疫反应外， 7防御激素水杨酸（SA），也直接参与病原体的识别。有趣的是， 8叶绿体在免疫应答过程中动态改变形态，发出充满基质的管状 9个突起称为基质。这些诱导的基质利用细胞骨架延伸，然后锚到细胞骨架上。 10个核，这有利于叶绿体的核周聚集和叶绿体产生的氢的运输 11过氧化物（H2 O2）ROS和防御蛋白质的细胞核。此应用程序的总体目标是使用 12新的细胞生物学，遗传学，蛋白质组学和计算方法的组合，以解开 13种小孢子形成的机制基础及其在驱动核周叶绿体聚簇中的作用， 14随后从叶绿体向细胞核释放逆行免疫信号。具体而言，目标1将确定 15和表征子座形成和子座引导的叶绿体运动所需的蛋白质。这 16包括延伸所需的驱动蛋白马达和与基质外被膜相关的蛋白质 17，可能驱动子座启动或调节。将进行无偏倚的正向遗传筛查， 18鉴定其它子实体特异性组分。目的2将研究子实体所需的免疫信号 19诱导和释放H2 O2作为一个特定的退化叶绿体信号。小座的作用 将检查由SA和H2 O2信号传导组成的免疫信号传导的扩增。的关系 将研究21种不同的H2 O2来源、免疫应答期间的细胞器运动和PCD，以确定 22 H2 O2如何在细胞外传播到细胞内来源以调节先天性免疫应答。功能 23在H2 O2信号传播过程中，将使用子座和叶绿体定位进行检查- 在目标1中表征的24种特异性突变体。目标3将集中于病原体效应物如何影响基质， 25细胞器，和细胞骨架动力学作为毒力策略。另外，机械基础如何三 将确定26种效应物破坏基质和细胞器动力学。理解不同的角色 PCD和先天免疫过程中的27个细胞器将为细胞死亡和细胞凋亡提供统一的机制基础。 28生存过程中发生的反应传染性病原体。我们的模型系统的结果将 29广泛影响对影响先天免疫的细胞器与核通讯的理解， 30种传染病

1 Project Summary 2 This project focuses on the chloroplast as central player in the generation of immune signals and the 3 regulation of programmed cell death (PCD) required for innate immune responses against pathogen infection. 4 Although mitochondria play a central role during mammalian PCD, emerging evidence suggests that in plants 5 chloroplasts have a critical function in executing localized PCD that limits pathogen spread. Chloroplasts in 6 addition to being involved in the generation of immune signals, such as reactive oxygen species (ROS) and the 7 defense hormone salicylic acid (SA), also participate directly in the recognition of pathogens. Interestingly, 8 chloroplasts dynamically change their morphology during immune responses and send out stroma-filled tubular 9 projections called stromules. These induced stromules use the cytoskeleton to extend and then anchor to the 10 nucleus, which facilitate perinuclear clustering of chloroplasts and transport of chloroplast-generated hydrogen 11 peroxide (H2O2) ROS and defense proteins to the nucleus. The overall goal of this application is to use a 12 combination of novel cell biology, genetics, proteomics and computational approaches to unravel the 13 mechanistic basis of stromule formation and their role in driving perinuclear chloroplast clustering and 14 subsequent release of retrograde immune signals from chloroplasts to nuclei. Specifically, Aim 1 will identify 15 and characterize proteins required for stromule formation and stromule-directed chloroplast movement. This 16 includes the kinesin motor required for extension and proteins associated with the outer envelope of stromules 17 that may drive stromule initiation or regulation. An unbiased forward genetic screen will be conducted to 18 identify other stromule specific components. Aim 2 will investigate immune signals required for stromule 19 induction and the release of H2O2 as a specific retrograded chloroplast signal. The role of stromules in 20 amplification of immune signaling consisting of SA and H2O2 signaling will be examined. The relationship of 21 different H2O2 sources, organelle movement and PCD during immune responses will be studied to determine 22 how H2O2 propagates extracellularly to intracellular sources to regulate innate immune responses. The function 23 of stromules and chloroplast positioning during H2O2 signal propagation will be examined using the stromule- 24 specific mutants characterized in Aim 1. Aim 3 will focus on how pathogen effectors affect stromules, 25 organelle, and cytoskeleton dynamics as a virulence strategy. In addition, mechanistic basis of how three 26 effectors disrupt stromules and organelle dynamics will be determined. Understanding the role of different 27 organelles during PCD and innate immunity will provide a unified mechanistic basis of cell death and cell 28 survival process that occur in response to infectious pathogens. The results from our model systems will 29 impact broadly on understanding of organelle-to-nuclear communication that influence innate immunity against 30 infectious diseases.