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Diversity of Streptomyces spp. causing potato common scab in Eastern Canada

Amy Novinscak: Université de Moncton

<div>Common scab is a potato disease that significantly decreases the market value of potato tubers following the development of necrotic lesions on their surface. <em>Streptomyces scabiei </em>is the main causal agent of common scab; however, other closely related species, including <em>S. acidiscabies</em> and <em>S. turgidiscabies</em>, have also been shown to cause the disease. In this study, we focused on the genetic and phenotypic diversity of <em>Streptomyces </em>spp. able to infect tubers in Prince Edward Island, the main potato-producing province in Canada. Three hundred and twenty-five pathogenic <em>Streptomyces</em> cultures were retrieved from the lesions of potatoes harvested from three separate geographical locations using selective culture media and PCR analyses. Genome fingerprinting analyses using repetitive elements polymerase chain reactions (ERIC- and BOX-PCR) revealed 25 distinct genetic groups. The geographical distribution of these groups was analysed and genomes of predominant species have been sequenced using Next-Gen sequencing. A multi-locus sequence analysis based on 16S rRNA, <em>gyrB</em>, <em>rpoD</em> and <em>rpoB</em> was performed, as well as sequence analyses of pathogenesis-related genes encoding for thaxtomin synthase (<em>txt</em>), tomatinase (<em>tomA</em>), and necrosis protein (<em>nec1</em>). The core and pan-genomes of the <em>Streptomyces </em>spp. were also identified. The virulence of the various strains is currently being analysed through pathogenicity tests (<em>in vitro</em> and on potato tuber slices).</div>