Pathogenicity of the Pseudomonas syringae DC3000 Bacterium towards the Common Bean and Isolation of the Sources of Resistance

The paper reports on the studies conducted to investigate the pathogenicity of the model bacterium Pseudomonas syringae pv.tomato (Pst) DC3000 towards Fabaceae crops and to identify sources of resistance to Pst DC3000 in the common bean. The material for the study was 24 common bean cultivars, one fava bean cultivar, and one common pea cultivar. To study virulence of the analyzed bacterium towards legume crops, five inoculation variants at different stages of plant ontogenesis, namely seedlings, cotyledonary leaves, primordial leaves, and first pair of true leaves formation, were used. According to the results of the analysis of variance, there is a significant effect of both the inoculation method and variety on the infection outcome: 63.6% of variance explained by the inoculation method, 29.8% of the variance by variety, and 6.6% by the interaction of these two factors. Primordial leaf phase proved to be the most sensitive stage of ontogenesis for plant infection, with the infection score for the analyzed common bean varieties of 0.5–4 points. When fava bean and common pea varieties were inoculated with Pst DC3000, the average infection score in seedlings and plantlets was approximately 0–0.5 points and did not statistically differ from the plants in the control group. The correlation coefficient between the manifestation of leaf wilting and chlorosis at the time of the first and second surveys was significant ((p < 0.005)—r = 0.95, Sr = 0.06, and t_r 16.38 > t_theor 2.01). When 22 collection accessions of common bean were evaluated for resistance to Pst DC3000, the infection core on the 14th day ranged from 0 to 4 points. Five domestic and foreign varieties, namely Supernano, Minidor, Alonso, Rosinka, and Nadezhda, showed high resistance to the Pst DC3000 bacterium, with the disease development (R) rate and disease spread (P) rate at the level of 0–12%.