Roles of auxin during Pseudomonas syringae pathogenesis

植物激素生长素控制着植物生长发育的许多方面。然而，生长素对细菌植物相互作用的影响尚不清楚。本项目旨在更好地了解生长素促进由两种植物病原体引起的疾病的机制：丁香假单胞菌，多种植物细菌性斑点病的病因，以及Dickeya spp.，细菌性软腐病的病因，马铃薯的重要病原体。已有研究发现，生长素在拟南芥（Arabidopsis thaliana）的p.s ynringae发病过程中发挥了多种作用，包括抑制宿主防御和调节病原菌基因表达。目前的项目将重点研究三个问题：1)丁香假单胞菌产生的生长素如何影响宿主生物学从而促进疾病易感性？ii)生长素如何影响丁香假单胞菌毒力因子的表达？iii) Dickeya产生的生长素是否导致马铃薯病害？本项目的研究结果将有助于进一步了解植物生长素在丁香假单胞菌（P. syringae）和丁香假单胞菌（Dickeya spp）发病过程中的作用。由于这两种病原菌都感染大量的作物，通过本工作获得的知识将为了解其他重要的植物-病原菌相互作用奠定基础，从而促进设计更有效的疾病控制策略。此外，由于这些研究包括对美国马铃薯农民直接关注的病原体Dickeya的调查，结果将提供相关信息，可用于加强疾病管理实践，并为广泛的疾病控制提供新的目标。技术段落：吲哚-3-乙酸（IAA）是生长素的一种天然形式，促进紫丁香的生长。番茄菌株DC3000 （PstDC3000）对拟南芥的影响。IAA不仅是一种植物激素，也是许多植物相关微生物合成和/或响应的微生物信号分子。因此，IAA可能通过几种不同的机制促进发病，包括抑制宿主防御，改变宿主生理，直接影响病原体生物学。本项目的主要目的是阐明生长素在拟南芥和其他宿主感染过程中促进PstDC3000毒力的机制。两个研究小组之间的多学科合作涉及两个实验室的互补专业知识，并将利用细菌遗传学，最先进的全球转录分析和代谢谱来进一步了解生长素在调节植物与病原体相互作用中的作用。这项研究的结果将是变革性的，因为它们将有助于发现植物与微生物相互作用中涉及的决定因素。该项目将为研究感染过程中调节病原体和宿主基因表达的信号分子和事件提供有价值的新见解。具体而言，该项目有以下目标：1)研究生长素对PstDC3000的直接作用；2)鉴定和表征对生长素敏感性改变的PstDC3000突变体；3)研究丁香假单胞植物来源的生长素在发病过程中的作用；4)研究病原菌来源的生长素在农业相关植物与病原菌相互作用中的毒力贡献。

Non-Technical ParagraphThe plant hormone auxin controls many aspects of plant growth and development. However, the impact of auxin on bacterial plant interactions is not well understood. This project seeks to better understand the mechanisms through which auxin promotes disease caused by two plant pathogens: Pseudomonas syringae, the causal agent of bacterial speck disease of a variety of plants, and Dickeya spp., the causal agent of bacterial soft rot, an important pathogen of potato. Previous research has found that auxin plays multiple roles during P. syringae pathogenesis of Arabidopsis thaliana, including suppression of host defenses and regulating pathogen gene expression. The current project will focus on three questions: i) How does auxin produced by P. syringae impact host biology to promote disease susceptibility? ii) How does auxin impact expression of P. syringae virulence factors?, and iii) Does auxin production by Dickeya contribute to disease on potato? The results of this project will be an improved understanding of the roles of auxin during pathogenesis of P. syringae and Dickeya spp. As both pathogens infect a large number of crops, knowledge gained through this work will serve as a foundation for understanding other important plant-pathogen interactions to facilitate the design of more effective disease control strategies. In addition, since these studies include the investigation of a pathogen, Dickeya, that is of immediate concern to U.S. potato farmers, results will provide pertinent information that can be used to enhance disease management practices and provide new targets for broad range disease control.Technical Paragraph: Indole-3-acetic acid (IAA), a naturally occurring form of auxin, promotes growth of P. syringae pv. tomato strain DC3000 (PstDC3000) on A. thaliana. IAA, in addition to being a plant hormone, is also a microbial signaling molecule that many plant-associated microbes synthesize and/or respond to. Thus, IAA can potentially act through several different mechanisms to promote pathogenesis, including suppressing host defenses, altering host physiology, and directly impacting pathogen biology. The primary goal of this project is to elucidate the mechanisms through which auxin promotes the virulence of PstDC3000 during infection of A. thaliana and other hosts. The multidisciplinary collaboration between the two research groups engages the complimentary expertise in the two labs and will utilize bacterial genetics, state of the art global transcriptional analysis and metabolic profiling to further understanding of the roles auxin plays in regulating plant-pathogen interactions. The results of this study will be transformative, as they will be instrumental in the discovery of determinants involved in plant-microbe interactions. The project will provide valuable new insight into the signaling molecules and events regulating pathogen and host gene expression during infection. Specifically, the project has the following objectives: 1) Investigating the direct effects of auxin on PstDC3000, 2) Identification and characterization of PstDC3000 mutants with altered sensitivity to auxin, 3) Investigate the roles of P. syringae-derived auxin during pathogenesis, and 4) Investigating the contribution of pathogen-derived auxin to virulence in agriculturally relevant plant-pathogen interactions.