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

微生物引起的植物疾病对农业生产力有重大影响，从而影响不断增长的人类人口的食物和纤维供应。为了对抗潜在的病原体，植物进化出了一种复杂的防御系统，它可以检测潜在病原体的存在，并激活多种反应来限制病原体的增殖，防止组织损伤。其中一些反应包括加强细胞壁和释放具有抗菌特性的分子。尽管有这些和其他的防御反应，疾病仍然会发生，因为病原体也进化了多种策略来避开植物的防御系统。这个项目的目标是了解植物如何加强细胞壁和释放抗菌剂，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并减少其经济和社会影响的新方法带来曙光。该项目的研究活动将用于吸引来自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，他们也将成为外联活动的导师。植物内膜系统对于病原菌的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菌特性的蛋白质运送到细胞外环境(质外体)。这两种反应都需要蛋白质分泌，这一过程已经被研究过，但仍然知之甚少，特别是在植物中，因为它涉及多个高度动态的亚细胞室、运输途径和蛋白质网络。由于内膜介导的过程在植物-病原菌相互作用中是必不可少的，这些过程也是病原菌毒力因子的靶标，但病原菌使用的策略尚未得到很好的表征。这个项目的主要目的是深入了解调节植物防御反应的分泌途径和信号网络，以及这些过程是如何被细菌病原体的毒力因子靶向的。该项目将使用涉及活细胞成像和蛋白质组学技术的多学科方法，结合生物、遗传和生化分析来确定亚细胞隔室、运输途径和蛋白质网络，这些蛋白质网络在细胞壁重塑和向质外体运送抗微生物蛋白质方面发挥作用。该项目还将提供一个框架，以比较生活方式不同的细菌病原体如何触发不同的分子和细胞反应，以及适应的细菌病原体的毒力因子之间的协同作用如何颠覆植物免疫反应。该项目由植物生物相互作用计划和既定的激励竞争性研究计划(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智力优势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.