Understanding local and systemic signaling pathways in plant immunity

了解植物免疫中的局部和系统信号通路

• 批准号: RGPIN-2020-06687
• 负责人: Cameron, Robin
• 金额: $ 3.42万
• 依托单位: McMaster University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=740741
• 关键词: Understanding; local; systemic; signaling; pathways

Plants possess disease resistance pathways to combat microbial infections. Each year an estimated 10 to 40% of world food production is lost to disease despite resistant crop varieties and pesticide application. In view of these losses, the goal of my research is to understand plant immune responses to inform efforts to manipulate plant immunity to improve disease resistance in crops. In locally infected leaves, individual plant cells perceive pathogen-associated molecules called PAMPs to initiate PAMP-Triggered Immunity (PTI). Local defense can induce Systemic Acquired Resistance (SAR), in which mobile signals are produced and transported from induced to distant leaves to establish resistance to future pathogen attack. Some plants become more resistant to a particular pathogen as they age and exhibit Age-Related Resistance (ARR). For example, young 3 to 4 week-old Arabidopsis plants are susceptible to the bacterial pathogen, Pseudomonas syringae pathovar (pv) tomato (P.syringae), but exhibit resistance to the same pathogen as mature 6 to 7 week-old plants. My research team seeks to understand the molecular genetic and biochemical basis of plant immunity using the model system, Arabidopsis and P. syringae. We demonstrated that the plant hormone salicylic acid (SA) performs a previously unknown function as an antimicrobial agent that suppresses the growth and biofilm formation of P.syringae in plant intercellular spaces during ARR and PTI. Biofilms consist of adherent bacterial cells surrounded by an extracellular matrix that are thought to protect bacteria from host defense. To our knowledge, we are the first lab to show that P. syringae forms biofilms in leaf intercellular spaces and demonstrate that biofilm formation contributes to P.syringae success. We will perform parallel transcriptomic analysis of the plant and pathogen to understand how mature plants perceive normally virulent pathogens and how PTI- and ARR-responding plants inhibit P.syringae biofilm formation. My lab has made significant progress in understanding how SAR mobile signals including DIR1 access the phloem for movement from induced to distant leaves and identified proteins that accumulate in the phloem and contribute to SAR, perhaps by interacting with DIR1. We will take advantage of DIR1's role in both SAR-induced and distant leaves to identify the molecular components responsible for DIR1 movement out of SAR-induced leaves and identify DIR1 interactors that restrict its movement under non-inductive conditions and/or facilitate DIR1 movement upon SAR activation by performing DIR1 movement assays using SAR mutants and protein-protein assays (TurboID, co-IPs + LC-MS/MS). DIR1's cellular route during SAR will also be examined by conditionally blocking access to the phloem to observe the effect on movement of DIR1-iLOV (iLOV:fluorescent peptide), monitored using fluorescence microscopy, to reveal fundamental cellular information about the path taken by DIR1 during SAR.

植物拥有对抗微生物感染的抗病途径。尽管有抗性作物品种和使用杀虫剂，但每年估计有10%至40%的世界粮食产量因疾病而损失。鉴于这些损失，我的研究目标是了解植物免疫反应，为操纵植物免疫以提高作物抗病能力提供信息。在局部感染的叶片中，单个植物细胞感知到与病原体相关的称为PAMPs的分子，从而启动pamp触发免疫（PTI）。局部防御可以诱导系统性获得性抗性（SAR），在此过程中，移动信号从诱导叶片产生并传输到远处的叶片，以建立对未来病原体攻击的抗性。一些植物随着年龄的增长，对特定病原体的抵抗力会增强，并表现出与年龄相关的抗性（ARR）。例如，3 - 4周龄的拟南芥幼苗对细菌病原体丁香假单胞菌（pv）番茄（p.s ynringae）敏感，但对6 - 7周龄的成熟植株却表现出同样的抗性。我的研究团队试图通过拟南芥和丁香叶模型系统来了解植物免疫的分子遗传和生化基础。我们证明了植物激素水杨酸（SA）在ARR和PTI过程中发挥了一种以前未知的抗菌作用，它可以抑制p.s ynringae在植物细胞间隙的生长和生物膜的形成。生物膜由细胞外基质包围的粘附细菌细胞组成，被认为可以保护细菌免受宿主的防御。据我们所知，我们是第一个证明丁香假单胞菌在叶片细胞间隙形成生物膜的实验室，并证明生物膜的形成有助于丁香假单胞菌的成功。我们将对植物和病原体进行平行转录组学分析，以了解成熟植物如何感知正常毒性病原体，以及响应PTI和arr的植物如何抑制丁香假单胞菌生物膜的形成。我的实验室在理解包括DIR1在内的SAR移动信号如何进入韧皮部从诱导叶到远处叶的运动方面取得了重大进展，并鉴定了韧皮部中积累的蛋白质，这些蛋白质可能通过与DIR1相互作用来促进SAR。我们将利用DIR1在SAR诱导和远端叶片中的作用，确定负责DIR1从SAR诱导叶片中移动的分子成分，并通过使用SAR突变体和蛋白质-蛋白质分析（TurboID, co-IPs + LC-MS/MS）进行DIR1移动分析，确定在非诱导条件下限制其移动和/或在SAR激活时促进DIR1移动的DIR1相互作用物。在SAR期间，DIR1的细胞路径也将通过有条件地阻断韧皮部的通道来观察DIR1-iLOV （iLOV：荧光肽）运动的影响，使用荧光显微镜进行监测，以揭示DIR1在SAR期间所采取的路径的基本细胞信息。