Characterization of Pseudomonas syringae pv. morsprunorum originating from sweet cherry and plum in Serbia

Pseudomonas strains originating from symptomatic (bacterial spot) leaf tissues of sweet cherry (Topola, Sumadija) and plum (Krusedol Selo, Srem) were isolated during 2016 and 2020, respectively. Based on the findings yielded by classical microbiological methods, LOPAT (+---+), GATTa (--++) and pathogenicity tests performed on detached fruitlets (sweet and sour cherry) and pods (bean pods), all strains were confirmed to belong to P. syringae pv. morsprunorum. The detection of cfl gene allowed strains that belong to race 1 to be identified. The DNA fingerprinting patterns obtained with four rep-PCR (BOX and ERIC), RAPD-PCR (M13), and IS50-PCR (IS50) methods revealed that the seven tested sweet cherry and plum P. s. pv. morsprunorum strains, as well as comparative KBNS71 and the reference strain CFBP 2119, were genetically heterogeneous. Conversely, MLSA based on the four-gene-based scheme (gapA, gltA, gyrB, and rpoD) indicated genetic homogeneity among all tested Serbian sweet cherry and plum strains, as well as P. s. pv. morsprunorum race 1 strains from the NCBI. Although the MLSA findings indicate that the sweet cherry and plum strains used in this study are 100% identical, as they might have different virulence genes, genome sequencing should be performed to eventually find the strain sub-clades based on the host.