Genetic and phenotypical diversity of Pseudomonas syringae population in the Russian Federation

Proteobacteria comprising species of Pseudomonas syringae group cause diseases of many plants around the world. The phytopathogen has a complex taxonomic structure, which is constantly being revised due to the emergence of new molecular and biochemical diagnostic methods. Here for the first time, we describe the genetic and phenotypic diversity of 57 strains of Pseudomonas syringae isolated from affected soybeans, cereals, sunflowers, and other plants in the Russian Federation from 1950 to 2019. Genetic diversity was assessed by Multi Locus Sequence Analysis (MLSA) using fragments of the genes of glyceraldehyde-3-phosphate dehydrogenase (gapdh), the DNA-directed RNA polymerase subunit D (rpoD), gyrase (topoisomerase) B subunit (gyrB), and citrate synthase I (gltA). The synthesis of syringomycin and coronatine by bacteria was assessed by the reaction of susceptible yeast culture, seedlings of barley, tomato, and sunflower, and by presence of toxin genes confirmed by PCR test. The pathogenicity of the strains was confirmed on seedlings of dicotyledonous and monocotyledonous plants of peas, soybean, sunflowers, barley and wheat, as the most affected crops. The sensitivity of bacteria to 10 antibiotics of the main mechanisms of activity and two bactericidal commercial products was tested by standard disc method. The obtained results showed a high genetic homogeneity of the Russian population of P. syringae, which infects various agricultural crops, and an increase in the proportion of antibiotic-resistant strains over the years.