Diversity of soybean bacterial blight pathogen Pseudomonas savastanoi pv. glycinea in the Russian Federation

One of the most harmful bacterial diseases of soybean is bacterial blight caused by bacterium Pseudomonas savastanoi pv. glycinea. The pathogen can reduce soybean yield (up to 40 %), oil content and seed germination. To manage the pathogen damage, protection measures should be comprehensive, the most cardinal of which is breeding for resistance. To obtain resistant varieties, it is necessary to understand the diversity of the pathogen in the area and to breed against the most common and harmful forms of the pathogen. In this regard, the aim of the study was to characterize Pseudomonas savastanoi pv. glycinea strains circulating in the Russian Federation as casual agents of bacterial blight of soybean. 12 strains of the soybean bacterial blight pathogen were isolated from soybean plant parts and seeds grown in different regions of the Russian Federation. The isolated strains were identical to the reference strain Psg CFBP 2214 in fluorescence, colony morphology on King B medium and LOPAT test results (+, –, –, –, –, +) and formed an amplicon in specific PCR analysis of cfl (coronafacate ligase) gene. The strains had different virulence to Kasatka soybean plants, and the width of symptomatic zone when leaves were artificially inoculated ranged from 3.23 mm (in strain G7) to 6.53 mm in strain G4. Comparison of the obtained gltA and ITS 16S-23S rRNA gene sequences showed a high (95.8…98.8 %) identity to the bacterial blight pathogen strains deposited to NCBI Genbank, and phylogenetic analysis showed a low intra-strain genetic polymorphism. Analysis of the race composition of the strains showed that the race 4 was predominant in the Russian Federation.