Arabidopsis basil immunity to human and plant pathogens

描述（由申请人提供）：本研究的长期目标是阐明植物对人类病原体的免疫和植物对植物病原体的敏感性之间明显相互交织的分子基础。本研究采用拟南芥-丁香假单胞菌/肠出血性大肠杆菌（EHEC）病理系统模型。最近的一项研究表明，转基因表达丁香假单胞菌毒力蛋白AvrPto（一种假定的GTPase激活蛋白）可抑制拟南芥细胞壁外免疫，使丁香假单胞菌和EHEC O157:H7大量繁殖。本研究要验证的中心假设是：i)植物利用细胞壁免疫来抵御包括人类病原体在内的许多微生物；ii)丁香假单胞菌毒力蛋白通过抑制极化胞外囊泡运输（如AvrPto）或下调微生物激活的免疫信号转导途径（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)人类病原体对拟南芥细胞壁外免疫激活的研究；2)丁香假单胞菌抑制宿主细胞壁免疫的毒力蛋白全基因组鉴定；3)AvrPto抑制极化胞外囊泡运输的机制阐明；4)HopPtoD2下调免疫相关信号转导通路的机制阐明。5)拟南芥细胞壁免疫的功能基因组学研究。结合分子遗传学，细胞生物学，转基因，显微和发病方法将被使用。拟议的研究不仅有助于了解细菌病原体如何在高等真核生物中引起疾病，而且还将深入了解人类病原体污染和植物定植的分子基础，这已经成为由于食用新鲜蔬菜食物中毒而引起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.