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POSTERS: Proteomics / metabolomics / genomics

Comparative genomic and phylogenomic analyses of the sweetpotato soil rot pathogen, Streptomyces ipomoeae.
Natasha Ruschel Soares - Louisiana State University. Kuei-Ting Yang- Louisiana State University, Christopher Clark- Louisiana State University Agricultural Center, Jonathan Badger- National Institutes of Health, Jose Huguet-Tapia- University of Florida, Gregg Pettis- Louisiana State University Agricultural

Ŕĺ°~µan data-contrast="auto" lang="EN-US" class="TextRun SCXW27529777 BCX0" xml:lang="EN-US">Previous phylogenomic analysis suggested that the common scab pathogen Streptomyces scabiei and the soil rot pathogen Streptomyces ipomoeae (Si) are derived from a shared pathogenic ancestor. Despite this relationship, these pathogens differ substantially in host range, virulence factor production and associated disease symptoms, and it is our hypothesis that such differences are related to niche development by Si. S. scabiei contains pathogenicity islands at conserved loci, including a mobile island at aviXI, which contains genes (txt) for production of the phytotoxin thaxtomin. To gain insights into the Si genome, here we have performed comparative analyses involving both virulent and avirulent strains of Si, as well as other plant pathogenic and saprophytic Streptomyces spp. We found that the txt cluster has apparently become fixed within the Si genome separately from aviXI, where a small excisable island still exists. Using ortholog gene searches, we have defined a Si pathogen-specific genome (SiPSG), which comprises 153 ortholog groups. It is anticipated that genes within the SiPSG contribute to the unique aspects of soil rot disease. Comparative txt gene analysis has provided evidence that thaxtomin production in Si is under unusually strong regulation by bldA, a major regulator of secondary metabolism in the genus. Overall, the results here will facilitate elucidation of the mechanisms governing virulence in this novel Streptomyces plant pathogen.