Arabidopsis basil immunity to human and plant pathogens

描述(申请人提供)：这项研究的长期目标是阐明植物对人类病原体的免疫力和植物对病原体的敏感性的明显相互交织的分子基础。本研究以拟南芥-丁香假单胞菌/肠出血性大肠杆菌(EHEC)为模型进行研究。最近的一项研究表明，转基因表达紫丁香疫霉毒力蛋白AvrPto(一种可能的GTP酶激活蛋白)抑制了拟南芥基于细胞壁的胞外免疫，不仅允许紫丁香疫霉的大量繁殖，而且允许EHEC O157：H7的大量繁殖。这项研究要检验的中心假设是：i)植物利用基于细胞壁的免疫来抵御包括人类病原体在内的许多微生物，以及ii)紫丁香菌毒力蛋白通过抑制极化的胞外小泡运输(例如AvrPto)或下调微生物激活的免疫信号转导途径(例如蛋白酪氨酸磷酸酶HopPtoD2)来抑制这种宿主免疫。具体目标是：1)研究人类病原体对拟南芥基于细胞壁的细胞外免疫的激活作用，2)基因组范围内鉴定抑制寄主基于细胞壁的免疫的毒力蛋白，3)阐明AvrPto抑制极化的胞外小泡运输的机制，4)阐明HopPtoD2下调免疫相关信号转导途径的机制，以及5)用功能基因组方法表征拟南芥基于细胞壁的免疫。将使用分子遗传学、细胞生物学、转基因、显微和发病机制等方法相结合。这项拟议的研究不仅将有助于了解细菌病原体如何在高等真核生物中致病的基础知识，还将有助于深入了解人类病原体污染和定植植物的分子基础，人类病原体已成为因食用新鲜蔬菜食品而引起食物中毒的主要公共卫生和生物恐怖问题。

DESCRIPTION (provided by applicant): The long-term goal of this research is to elucidate the apparently intertwined molecular bases of plant immunity to human pathogens and plant susceptibility to plant pathogens. We use the model Arabidopsis-Pseudomonas syringae/enterohemorrhagic Escherichia coli (EHEC) pathosystem for this research. A recent study shows that transgenic expression of P. syringae virulence protein AvrPto (a putative GTPase activating protein) suppresses the cell wall-based extracellular immunity in Arabidopsis, allowing substantial multiplication of not only P. syringae, but also EHEC O157:H7. The central hypotheses to be tested in this research are: i) Plants uses the cell wall-based immunity to ward off many microbes, including human pathogens, and ii) P. syringae virulence proteins suppress this host immunity by either inhibiting polarized extracellular vesicle trafficking (e.g., AvrPto) or down-regulating the microbe-activated immunity signal transduction pathway (e.g., HopPtoD2, a protein tyrosine phosphatase). Specific aims are: 1) Investigation of the activation of Arabidopsis cell wall-based extracellular immunity by human pathogens, 2) Genome wide identification of P. syringae virulence proteins that suppress host cell wall-based immunity, 3) Elucidation of the mechanism by which AvrPto inhibits polarized extracellular vesicle trafficking, 4) Elucidation of the mechanism by which HopPtoD2 down-regulates the immunity-associated signal transduction pathway, and 5) Characterization of Arabidopsis cell wall-based immunity using functional genomic methods. A combination of molecular genetic, cell biological, transgenic, microscopic, and pathogenesis methods will be used. The proposed research will not only contribute to the fundamental knowledge of how bacterial pathogens cause disease in higher eukaryotes, but also will provide insight into the poorly understood molecular basis of contamination and colonization of plants by human pathogens, which have become a major public health and bioterror concern due to food poisoning from consuming fresh vegetable foods.