Translating extracellular ligand perception into a cytosolic Ca2+ signal: characterizing the role plant elicitor peptides and their receptor play in innate immune responses

该项目主要研究植物细胞免疫信号的信号转导系统，其总体目标是确定允许植物细胞膜受体蛋白感知病原微生物的分子机制，并将这种感知转化为防御反应。信号级联中的一个重要步骤是胞内钙离子的升高，这会引发下游的防御程序。研究将集中在一类植物激发子多肽(Pep)及其细胞膜受体(PEPR1)上。研究人员将测试PEP与PEPR1受体结合如何导致胞浆钙升高的模型。研究人员进行的初步研究表明，PEPR1受体具有鸟苷酸环化酶活性。该项目将研究细胞中的信号分子环鸟苷酰单磷酸(CGMP)是否由受体响应于导致PEP肽产生的病原体信号而在植物细胞中产生，以及cGMP的产生是否由于细胞膜上的环核苷酸门控离子通道的开放而升高胞内钙离子。免疫信号级联中的这些早期步骤将与下游防御反应联系在一起，例如限制毒力病原体(丁香假单胞菌)生长的抗菌素分子的产生，以及对无毒病原体(丁香假单胞菌avrRpt2)的过敏反应/程序性细胞死亡反应。该项目的首席研究员有招募高中生与实验室研究生合作的历史，以及接触少数族裔本科生项目并让这些学生参与研究的历史。这一外联和培训将在拟议的项目期间继续进行。首席调查员正在与当地一所高中的一名生物教师进行互动，并将与这名教师合作，招募高中生与本科生一起参与该项目的研究活动。

This project focuses on a signal transduction system involved in plant cell immune signaling; an overall aim is to identify molecular mechanisms that allow perception of pathogenic microbes by plant cell membrane receptor proteins and translation of this perception to defense responses. An essential step in the signaling cascade is a cytosolic Ca2+ elevation that evokes downstream defense programs. Studies will focus on a family of Plant Elicitor Peptides (Peps) and their cell membrane receptor (PEPR1). A model of how Pep binding to the PEPR1 receptor leads to cytosolic Ca2+ elevation will be tested by the investigators. Preliminary studies undertaken by the investigators indicate that the PEPR1 receptor has guanylyl cyclase activity. The project will investigate whether cyclic guanylyl monophosphate (cGMP), a signaling molecule in cells, is generated in plant cells by the receptor in response to pathogen cues causing Pep peptide generation, and if the cGMP production elevates cytosolic Ca2+ due to the opening of a cyclic nucleotide gated ion channel in the cell membrane. These early steps in the immune signaling cascade will be linked to downstream defense responses such as the generation of antimicrobial molecules that limit growth of a virulent pathogen (Pseudomonas syringae) and hypersensitive response/programmed cell death response to an avirulent pathogen (P. syringae avrRpt2).The Principal Investigator of the project has a history of recruiting high school students to work with graduate students in the laboratory, as well as accessing minority undergraduate programs and involving these students in research. This outreach and training will continue during the proposed project. The Principal Investigator has an ongoing interaction with a biology teacher at a local high school and will work with this teacher to recruit high school students to participate, along with undergraduate students, in the research activity of the project.