2008 Annual Report 1a.Objectives (from AD-416) The objective of this cooperative research project is to use genetic approaches to identify molecular components and mechanisms that regulate gene expression in Pseudomonas syringae pv. tomato DC3000 (hereafter DC3000), a pathogen of tomato and Arabidopsis. The project will focus primarily on regulatory pathways that are thought to be important in the development of disease. The materials and data generated by this effort will be analyzed by ARS to generate computational models for gene regulation. 1b.Approach (from AD-416) A wide variety of methodologies will be used to dissect gene regulation, and new strategies will be developed as required. The range of possible techniques include the generation, selection and screening of mutants under various conditions, the creation of targeted mutants using molecular methods, and the construction of strains that over-express genes of interest. In addition, the project is likely to employ high throughput techniques such as robotics to aid in the screening of large numbers of strains in parallel, or test the response of DC3000 in multiple environmental conditions. 3.Progress Report Research conducted under this agreement is monitored via weekly meetings between the ADODR and the cooperator. Both laboratory personnel supported by this project were on medical leave for the first part of the reporting period, and both subsequently resigned shortly after returning to work. These positions were revised and new personnel were filled and trained. Efforts to augment and screen the transposon mutant library have been restarted, and mutants in novel regulators are under construction. The major accomplishment for this reporting period is the release of a high-resolution map of core and variable regions of the P. syringae genome and the assignment of genes related to virulence and iron homeostasis to particular variable regions. The research addresses the Action Plan for National Program 303: Plant Diseases, Component 2: Biology, Ecology, Epidemiology and Spread of Plant Pathogens and Their Relationships with Hosts and Vectors and Problem Statement 2A: Pathogen Biology, Virulence Determinants and Genetics of the Pathogen.