2006 Annual Report 4d.Progress report. This documents research conducted under a specific cooperative agreement between ARS and University of Tennessee. Additional details of research can be found in the report for the parent project 5302-22000-007-00D, Epidemiology and Management of Xylella fastidiosa (Xf)-caused Diseases and Xf Insect Vectors. This research focuses on identifying key genes that underly metabolic pathways involving defense responses to Xylella fastidiosa (Xf) infection. Based on the functional genomics work conducted under the parent CRIS project. The initial effort is focused on a few target genes associated with signal transduction and defense responses such as methyl transferases; salicylic acid methyl transferase (SAMT) and jasmonic acid methyl transferase (JAMT). Full length copies of these genes from grape are being cloned from various PD resistant grape species (V. arizonica, V. aestivalis and V. shuttleworthi) as well as PD-susceptible wine grape, V. vinifera. Up/down stream non-coding regions, which correspond to regulatory regions, are also being sequenced using a genomic walking strategy. Functional tests for these genes are underway using an in intro expression system. The results of this research will contribute to characterizing the functions of candidate genes in grapevines that are associated with the defense responses to Xf infection and disease development, and to identify the mechanisms of the biosynthesis of metabolites in grape plants involved in defense pathways.