Agricultural Microbes Genome 2 Conference Agricultural Microbes Genome 2 Conference
Poster: Microbial Genome Sequencing/Programs
P01_06.html
The bacterium Erwinia carotovora subspecies atroseptica (Eca) is a commercially important potato pathogen. Eca and other soft rot erwinias secrete enzymes that degrade plant cell walls. However the basis of Eca's restricted host range is not clear, early events in establishing infection are not understood and the discovery of type III secretion (hrp) genes in other soft rot erwinias suggests that their pathogenicity is more complex than previously recognised. Here we describe: (1) a BAC library as a resource for studying the Eca genome; (2) probing the library with pathogenicity genes to identify regions of interest and (3) one-fold sequence coverage of random subclones from BAC of interest as a strategy for gene discovery. Two BACs that hybridised to a hrpN probe were sample sequenced which revealed various genes of interest, including: (1) an entire hrp gene cluster; (2) homologues of other known or putative pathogenicity genes from other Erwinia species, namely dspE (E. amylovora), hecAB and pecSM (E. chrysanthemi); (3) pectinolytic genes (4) homologues to Xylella fastidiosa genes, including haemolysin-like genes and (5) homologues to genes important in the pathogenicity of Agrobacterium tumefascians. Furthermore, many sequences are highly similar to Escherichia coli genes, but are differently located on the chromosome, indicating considerable genomic reorganisation between these two closely related species. This approach of sample sequencing selected BACs has identified many potential new Eca pathogenicity factors and comparison with the E. amylovora hrp cluster suggests that we have sequence information from >80% of potential open reading frames in this region.