Plant diseases caused by bacteria of the Pseudomonas syringae species are a serious threat to many crops. The group of proteobacteria Pseudomonas syringae plays an important role in the study of the pathogenesis and resistance of plants to bacterial diseases. The study described for the first time the genetic and phenotypic diversity of 57 strains of Pseudomonas syringae isolated from affected soybean, cereal, sunflower and other plants in the Russian Federation from 1950 to 2019.
The MLSA (Multilocus Sequence Analysis) method was used to assess genetic diversity, including analysis of fragments of glyceraldehyde-3-phosphate dehydrogenase (gapdh), subunit D of RNA polymerase (rpoD), gyrase B (gyrB) and citrate synthase I (gltA) genes. The synthesis of syringomycin and coronatine was evaluated using sensitive strains of yeast, barley, tomato and sunflower sprouts, as well as checking for the presence of toxin genes confirmed by PCR (Polymerase Chain Reaction). The pathogenicity of the strains was confirmed on the sprouts of the most frequently affected crops, namely peas, soybeans, sunflower, barley and wheat. The sensitivity of bacteria to 10 antibiotics and two bactericidal commercial products was tested using the standard disk method.
The results showed a high genetic homogeneity of the Russian P. syringae population infecting various crops, as well as an increase in the proportion of antibiotic-resistant strains over time. Thus, this study is important for the effective control of bacterial diseases of plants, as it gives an idea of the nature of the spread and characteristics of pathogenic strains, which allows us to develop more accurate strategies to combat them.
The bacterium Pseudomonas syringae is considered a model object in phytopathology and the functions of the genes responsible for virulence were shown on it, methods of genetic analysis of the population of phytopathogenic bacteria were worked out. A special feature of our study, which was carried out jointly with Professor A.N. Ignatov from the Agrobiotechnological Department of the RUDN University, was a comprehensive analysis of the population structure of this bacterium, including the so-called polyphase characterization, that is, analysis by different methods. The results showed that the pathogen population in Russia is genetically homogeneous, which is typical for subpopulations around the world. In the future, based on these data, it is planned to answer the question "How pathogen strains adapt to the conditions of a changing climate and, most importantly, what to do so that as a result of this their virulence and losses from them do not exceed current indicators and, ideally, decrease," said one of the authors of the study, assistant of the Department of Plant Protection - Rashit I. Tarakanov.