CAREER: Dissecting the cellular pathways and signaling networks orchestrating plant defense responses and their interplay with bacterial virulence factors

由微生物引起的植物病害对农业生产力具有重大影响，并因此影响到不断增长的人口的食物和纤维的可获得性。为了对抗潜在的病原体，植物已经进化出一种复杂的防御系统，该系统检测潜在病原体的存在并激活多种反应以限制病原体增殖并防止组织损伤。其中一些反应包括强化细胞壁和释放具有抗菌特性的分子。尽管有这些和其他防御反应，疾病仍然发生，因为病原体也进化出多种策略来避开植物防御系统。该项目的目的是了解植物如何强化细胞壁并释放抗菌剂，以及病原体如何干扰这些过程。这些知识将为控制植物病害和减少其经济和社会影响的新方法提供启示。该项目的研究活动将用于吸引代表性不足的少数群体的本科生，并将为博士后研究员和研究生提供多学科培训，他们也将在外联活动中担任导师。植物内膜系统对于病原体识别和防御反应的部署是必不可少的，例如细胞壁的重塑和将具有抗微生物特性的蛋白质递送到细胞外环境（质外体）。这两种反应都需要蛋白质分泌，这是一个已经研究过但仍然知之甚少的过程，特别是在植物中，因为它涉及多个高度动态的亚细胞区室，运输途径和蛋白质网络。由于内膜介导的过程在植物-病原体相互作用中是必不可少的，这些过程也是病原体毒力因子的靶点，但病原体使用的策略尚未得到很好的表征。该项目的主要目标是更深入地了解调节植物防御反应的分泌途径和信号网络，以及这些过程如何被细菌病原体的毒力因子靶向。该项目将使用多学科方法，包括活细胞成像和蛋白质组学技术，结合生物学，遗传学和生物化学测定，以确定亚细胞区室，运输途径和蛋白质网络在细胞壁重塑和抗菌蛋白质向质外体的传递中发挥作用。该项目还将提供一个框架，以比较具有不同生活方式的细菌病原体如何触发不同的分子和细胞反应，以及适应细菌病原体的毒力因子之间的协同相互作用如何破坏植物免疫反应。该项目由植物生物相互作用计划和刺激竞争研究的既定计划（EPSCoR）共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Plant diseases caused by microorganisms have a significant impact on agricultural productivity and, consequently affect the availability of food and fiber for an ever-growing human population. To fight potential pathogens, plants have evolved a complex defense system that detects the presence of potential pathogens and activates multiple responses to restrict pathogen proliferation and prevent tissue damage. Some of these responses include the fortification of the cell wall and the release of molecules with antimicrobial properties. In spite of these and other defense responses diseases still occur because pathogens have also evolved multiple strategies to avoid the plant defense system. The objective of this project is to understand how plants fortify the cell wall and release antimicrobials, and how pathogens interfere with these processes. This knowledge will shed light into new approaches to control plant diseases and reduce their economic and societal impact. The research activities from this project will be used to engage undergraduate students from under-represented minorities, and will provide multi-disciplinary training for postdoctoral fellows and graduate students, who will also be mentors in the outreach activities. The plant endomembrane system is essential for pathogen recognition, and for the deployment of defense responses such as the remodeling of the cell wall and the delivery of proteins with antimicrobial properties to the extracellular milieu (apoplast). Both of these responses require protein secretion, a process that has been investigated but remains poorly understood, especially in plants, as it involves multiple and highly dynamic subcellular compartments, trafficking pathways and protein networks. Because endomembrane-mediated processes are essential in plant-pathogen interactions, these processes are also targets of pathogen's virulence factors, but the strategies that pathogens use have not been well characterized. The main objective of this project is to gain a deeper understanding into secretory pathways and signaling networks regulating plant defense responses and how these processes are targeted by virulence factors from bacterial pathogens. This project will use multi-disciplinary approaches involving live-cell imaging and proteomics technologies in combination with biological, genetic and biochemical assays to identify subcellular compartments, trafficking pathways and protein networks operating in cell wall remodeling and delivery of antimicrobial proteins to the apoplast. The project will also provide a framework to compare how bacterial pathogens with contrasting lifestyles trigger distinct sets of molecular and cellular responses, and how synergistic interactions between virulence factors from adapted bacterial pathogens subvert plant immune responses. This project is jointly funded by the Plant Biotic Interactions Program and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.