Genetic diversity and virulence traits of Pseudomonas syringae pv. syringae isolated from various hosts in Serbia

In this study, we assessed the genetic relatedness of 11 representative Pseudomonas syringae pv. syringae (Pss) strains isolated in Serbia from different herbaceous and woody plant species, as well as one reference Pss strain, using various molecular tools such as repetitive element palindromic PCR, arbitrarily primed PCR, insertion sequences 50 PCR (IS50-PCR) and multilocus sequence analysis (MLSA). Their virulence traits were also assessed by inoculating detached pear and lilac leaves, as well as immature cherry fruitlets. The results indicated genetic heterogeneity among the strains, which formed a complex network with prominent clustering patterns. While four distinct groups could be recognised when comparative Pss strains from the database were included in the analyses, the strains in focus of this study segregated into two distinct genetic groups labelled PssG-2 and PssG-3. MLSA findings mostly matched the IS50-PCR results, while virulence assays helped distinguish sweet cherry (RE05, RE3) and pumpkin (PS-T71) strains as the most virulent. Only strain Pss25, originating from pear, exhibited host specificity.