Pseudomonas syringae pv. syringae has an extremely broad host range and is responsible for considerable agricultural crop losses throughout the world. For these reasons significant research has focused on the epidemiology and pathogenesis of this bacterium and its pathovars. The recent availability of genomic sequences has provided an important resource for gaining valuable understanding of this pathogen's virulence mechanisms and their regulation. Analysis of the 6.12 Mb Pseudomonas syringae pv. syringae B728a (B728a) genome identified the presence of nine distinct genomic regions encoding nonribosomal peptide synthetases (NRPSs). Three of the largest NRPS gene clusters are situated in close proximity to one another, thereby comprising a netabolite biosynthesis dense region of the genome. The peptide synthesis rich region is over 186 kb, accounts for over 3% of the B728a genome, and includes the syringomycin/syringopeptin (syr/syp) toxin clusters, the achromobactin siderophore cluster, and an uncharacterized NRPS (Psyr_2576-2577). The syr/syp genomic island encodes two phytotoxic cyclic lipopeptides (CLPs), syringomycin and syringopeptin, which serve as major virulence factors for P.s.s. B728a (Bender et al., 1999). These pore forming toxins are primarily responsible for the necrotic lesion formation characteristic of the disease brown spot of bean (Scholz-Schroeder et al., 2001). Due to the immense size of this metabolite rich region and the presence of two well-studied virulance factors, we are investigating this portion of the genome as a potential virulence "hot spot."