Functional Genomics of Phytophthora-Plant Interactions

植物病原微生物具有操纵寄主植物生化、生理和形态过程的能力。这些操纵是通过多种毒力和无毒力因子来实现的，这些毒力和无毒力因子可以促进感染或触发防御反应。卵菌纲是真核植物病原菌的一个独特的分支，有着独立的进化历史。其中，疫霉属（Phytophthora spp.）引起世界上一些最具破坏性的植物疾病，并且可以说是双子叶植物最具破坏性的病原体。例如，致病疫霉（Phytophthora infestans），爱尔兰马铃薯饥荒病原体，引起晚疫病，这是一种导致马铃薯和番茄生产数十亿美元损失的疾病，被认为是对全球粮食安全的重大威胁。在疫霉基因组联盟的框架内，疫霉属的结构基因组学研究正在顺利进行。然而，尽管它们的经济影响和奇异的遗传，卵菌仍然相对不足，在分子水平上和关键的分子事件调节basc致病性和植物反应仍然知之甚少。本项目的总体目标是利用病毒介导的基因表达技术对植物致病疫霉基因进行高通量功能筛选。具体目标是：1.使用基于马铃薯X病毒（PVX）的载体对番茄和烟草中的致病疫霉DNA进行高通量功能表达筛选，以鉴定引起抗性反应、疾病样症状和/或改变的疾病易感性的DNA。2.鉴定选定的致病疫霉DNA和编码蛋白的一级序列、基因表达、生物活性和感染期间的细胞定位。3.描述番茄和烟草对选择的致病疫霉DNA的分子和细胞反应。PVX表达系统的瞬时性质和最近开发的农杆菌二元PVX载体的使用将允许以前所未有的高通量速率对病原体基因进行功能分析。功能筛选将解开一组新的疫霉基因，触发植物细胞中的各种细胞和分子反应，并将牢固地建立病原体基因和植物过程之间的功能连接。从这些研究中获得的知识将为调节经济上重要的病理系统的关键分子过程提供重要的见解，并将为提高作物的抗病性提供新的工具。该项目产生的信息和材料将通过一个互动网站免费提供给科学界，该网站将包括所选DNA的注释数据库以及相应的表型和表达数据。该项目还将为功能基因组学和生物信息学的跨学科培训和推广活动提供出色的机会，这些活动围绕着使用壮观的功能测定，历史和经济上重要的疾病病理系统，以及植物和微生物之间相互作用的挑战性概念。1.病毒载体中的致病疫霉cDNA文库，包括在植物细胞中触发各种细胞和分子反应的疫霉基因的收集2。用疫霉效应子处理的番茄和烟草的表型和表达分析. Phytophthora Functional Genomics Database（PFGD）. Phytophthora Functional Genomics Database（PFGD）. S. Kamoun（kamoun. osu.edu）2. Mark Waugh（mew@ncgr.org）

Plant pathogenic microbes have the remarkable ability to manipulate biochemical, physiologc al and morphological processes in their host plants. These manipulations are achieved through a diverse array of virulence and avirulence factors that an either promote infection or trigger defense responses. Oomycetes, such as Phytophthora, downy-mildews and Pythium, form a unique branch of eukaryotic plant pathogens with an independent evolutionary history. Among the oomy etes, Phytophthora spp. cause some of the most destructive plant diseases in the world, and are arguably the most devastating pathogens of dicot plants. or example, Phytophthora infestans, the Irish potato famine pathogen, causes late blight, a disease that results in multibillion-dollar losses in potato and tomato production and is considered a significant threat to global food security. Structural genomics studies of Phytophthora are well under way within the framework of the Phytophthora Genome Consortium. However, despite their economic impact and singular phylogeny, oomycetes remain relatively understudied at a molecular level and key molecular events modulating basc pathogenicity and plant response remain poorly understood. The overall obje tive of this project is to use the technology of virus-mediated gene expression to carry out high throughput fun tional screening of P. infestans genes in plants. The specific objectives are to: 1. Perform high throughput functional expression screening of P. infestans DNAs in tomato and tobacco using a potato virus X (PVX)-based vector to identify DNAs that indu e resistance responses, disease-like symptoms and/or altered disease susceptibility. 2. Characterize the selected P. infestans DNAs and the encoded proteins with regards to primary sequence, gene expression, biological activity, and cellular localization during infection. 3. Characterize the molecular and cellular responses of tomato and tobacco to the sele ted P. infestans DNAs. The transient nature of the PVX expression system and the use of a recently developed Agrobacterium binary PVX vector will allow functional analysis of pathogen genes at an unprecedented high throughput rate. The functional screening will unravel a battery of novel Phytophthora genes that trigger a variety of cellular and molecular responses in plant cells and will firmly establish functional connections between pathogen genes and plant processes. The knowledge gained from these studies will provide significant insight into key molecular processes regulating an economically important pathosystem and will provide novel tools for improvement of disease resistan e in crop plants. Information and material generated from this project will be made freely available to the s ientific community through an interactive website that will include an annotated database of the selected DNAs and corresponding phenotype and expression data. The project will also offer outstanding opportunities for interdis iplinary training and outreach activities in functional genomics and bioinformatics revolving around the use of spectacular functional assays, historically and economically important disease pathosystems, and challenging concepts on the interaction between plants and microbes. Deliverables: 1. Libraries of P. infestans cDNAs in virus vectors, including collection of Phytophthora genes that trigger various cellular and molecular responses in plant cells2. Phenotypic and expression analyses of tomato and tobacco treated with Phytophthora effectors.3. Phytophthora Functional Genomics Database (PFGD).Contact Information for Deliverables: 1. S. Kamoun (kamoun.1@osu.edu)2. Mark Waugh (mew@ncgr.org)