Functional Genomics of Phytophthora-Plant Interactions

Ohio State University Research Foundation -Do Not Use, Columbus OH

Investigators

Abstract

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 cells 2. 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)