Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: March 16, 2007
Publication Date: February 20, 2008
Citation: Wanner, L.A. 2008. Single common scab-causing Streptomyces species characterize individual potato fields. American Journal of Potato Research. 85(1):32.
Common scab reduces potato quality and marketability in the US and worldwide, and is caused by a few species in the large genus of soil bacteria Streptomyces. At least eleven common scab-causing Streptomyces species have been described world-wide, based on 16s ribosomal DNA sequences, whole genome sequence similarity and biochemical characteristics. Recently, a large number of Streptomyces isolates has been obtained and characterized from multiple field locations in 19 US states and one Canadian province. Using PCR primers designed to unique sequences in the 16s ribosomal RNA genes, only five species were identified among 1000 isolates determined to be likely pathogens on the basis that they contained genes encoding the pathogenicity determinant thaxtomin. In almost all cases, only a single species was found in a field location, although different species were frequently found in adjacent locations. The most common species was S. scabies, the first-described and best known plant pathogenic species which occurs world-wide. Other species included two species previously described from Europe, S. europaeiscabiei and S. stelliscabiei, and a new species or strain recently described and found primarily in Idaho. Pathogenic S. acidiscabies was found in one location in New Brunswick. Genetic variation in chromosomal and pathogenicity-associated markers was identified within species from single field locations. The species found and their distribution appears to contrast with species distributions in Europe. The significance of different scab-causing species and genetic variation within species for severity and management of common scab is currently not known, although examples of differences in symptom severity and cultivar susceptibility between scab-causing species have been recently confirmed in Europe. (Poster, Plant protection, PAA membership 657).