Regulation of Arabidopsis immune function through RIN4 sub-cellular localization and exocyst interaction

植物采用分支免疫系统，在绝大多数植物与微生物的相互作用中预防疾病。其中一个分支识别包含在保守的微生物分子中的病原体相关分子模式(PAMP)。第二个分支识别效应蛋白，这是病原体编码的毒力因子。这两个分支利用共同的信号通路并诱导共同的输出，但对它们组成的网络中交叉的机制基础知之甚少。模式植物拟南芥的RIN4蛋白是一种枢纽蛋白，在调节这两个分支中起着关键作用，因此对RIN4的详细了解将为深入了解植物免疫系统的功能提供基础。这项工作将解决RIN4功能的三个方面。细菌效应蛋白诱导的RIN4亚细胞定位的改变对植物免疫系统的两个分支的活性有明显的影响。拟议的工作将确定RIN4的亚细胞定位如何影响其防御调节功能。初步数据还表明，RIN4与植物外囊的成分相互作用，外囊是一种多蛋白质复合体，调节囊泡运输和膜融合事件，这些事件在植物免疫系统的功能中发挥重要作用。这项拟议的工作将确定外囊与RIN4的相互作用如何有助于植物免疫功能。最后，RIN4在保卫细胞中发挥作用，调节气孔对细菌感染的反应。植物防止附生细菌病原体入侵的能力取决于它们关闭和保持气孔关闭的能力。RIN4和针对RIN4的细菌效应蛋白对保卫细胞功能的控制将被研究。研究目标将使用植物病理学、分子、生化和细胞生物学方法。广泛的影响：以农业为燃料和养料的趋势对优化作物生产力提出了巨大的需求。为了最有效地培育和/或设计粮食和生物燃料作物的抗病能力，同时最大限度地减少有害的副作用，如减产，需要关于组成植物免疫系统的网络内联系的基本知识。虽然这项工作将在拟南芥模型系统中完成，但这些发现将适用于农业上重要的植物，因为已经在所有被研究并被证明在几种作物的免疫功能中发挥重要作用的陆地植物中确定了RIN4同源物。调查结果将在会议上公布，并发表在同行评议的期刊上。PI在本科生、研究生和博士后水平上与服务不足的群体合作的记录得到了证实，包括最近毕业的一名西班牙裔博士生。该项目的资金还将支持小型文科学院的学生参加俄亥俄州立大学的暑期本科生研究体验项目。最后，在俄亥俄州立大学2012年夏季功能基因组学实用研讨会期间，PI将参与一个以植物免疫系统为重点的模块的组织和指导。

Plants employ a branched immune system that prevents disease in the vast majority of plant-microbe interactions. One branch recognizes pathogen associated molecular patterns (PAMPs) that are contained within conserved microbial molecules. A second branch recognizes effector proteins, which are pathogen-encoded virulence factors. These two branches utilize common signaling pathways and induce common outputs, yet little is known about the mechanistic basis of intersections within the network they comprise. The RIN4 protein of the model plant Arabidopsis thaliana is a hub protein with key roles in regulating both branches, thus a detailed understanding of RIN4 will provide fundamental insight into the function of the plant immune system. The work will address three aspects of RIN4 function. Changes in the sub-cellular localization of RIN4, which are induced by bacterial effector proteins, have distinct effects on the activity of the two branches of the plant immune system. The proposed work will determine how sub-cellular localization of RIN4 affects its defense regulatory function. Preliminary data also indicate that RIN4 interacts with components of the plant exocyst, which is a multi-protein complex that regulates vesicle trafficking and membrane fusion events that play important roles in the function of the plant immune system. The proposed work will determine how interaction of the exocyst with RIN4 contributes to plant immune function. Finally, RIN4 functions in guard cells to regulate stomatal aperture in response to bacterial infection. The ability of plants to prevent invasion by epiphytically growing bacterial pathogens depends on their ability to close and keep closed their stomata. Control of guard cell function by RIN4 and bacterial effector proteins that target RIN4 will be investigated. The research aims will be addressed using plant pathology, molecular, biochemical, and cell biological methods.Broader Impacts: The trend to use agriculture to fuel as well as feed the world places great demand on optimizing crop productivity. To most effectively breed and/or engineer disease resistance in food and biofuel crops while minimizing deleterious side effects, such as reduced yield, requires fundamental knowledge about connections within the network comprising the plant immune system. Though the work will be done in the Arabidopsis thaliana model system, the findings will be applicable to agriculturally important plants, as RIN4 homologs have been identified in all land plants examined and demonstrated to play important roles in immune function of several crop plants. Findings will be presented at meetings and published in peer-reviewed journals. The PI has a proven record of working with underserved groups at the undergraduate, graduate, and post-doctoral levels, including the recent graduation of an Hispanic Ph.D. student. Funds from the project will also support participation of students from small liberal arts colleges in the Summer Undergraduate Research Experience program at The Ohio State University. Finally, the PI will participate in the organization and instruction of a module focusing on the plant immune system during the 2012 Summer Practical Workshop in Functional Genomics at Ohio State.