Genetic Diversity among Plant Pathogenic Streptomyces Strains from Potato Fields in Northwest of Iran

Different species of Streptomyces are common in most types of soil. Some certain species are plant pathogenic especially on potato. This study was conducted to evaluate genetic diversity among some local Streptomyces spp. strains isolated from soil and infected tubers in potato farms in northwest of Iran. Repetitive DNA elements (BOX, ERIC and REP) as genetic markers were used for diversity studies and distance matrix was performed by UPGMA method. The cluster analysis showed 8, 5 and 7 distinct clusters with 85% similarity levels in ERIC, BOX and rep markers, respectively. Genetic clusters were moderately geographical region-depended but no significant correlations were found between clusters and other characteristics such as strains virulence or potato cultivars. Also, a dendogram was constructed from combined results of all three markers which showed four distinct groups at 80% similarity level. A close correlation was observed between strains virulence and these genetic groups. DNA sequencing followed by morphologic assay were used for detection of distinct species. The results demonstrated the existence of a considerable genetic diversity among collected plant pathogenic Streptomyces strains in the region. Also, the results suggest that combined results from all three ERIC, BOX and REP markers could be more useful and reliable than from each individual marker.