Characterization of Pseudomonas syringae pv. porri as the causal agent of bacterial leaf spot and blight of onion in Fars and Kermanshah provinces of Iran

The symptoms of bacterial leaf spot and blight on onion (Allium cepa L.) plants were observed in Fars (Eghlid) and Kermanshah (Bistoun) provinces with the rate of occurrence varying from 90 to 100% of the plants. In order to isolation and identification of the causal agent, suspicious samples were collected from infected fields. By culturing the samples on nutrient agar medium, 30 bacterial isolates were obtained. Pathogenicity test of the isolates on Allium spp. was performed and their pathogenicity was proved on onion, spring onion and leek. The isolates showed an identical total cell soluble protein pattern in SDS-PAGE. The isolates were similar to Pseudomonas syringae pv. porri based on phenotypic characteristics such as production of fluorescent pigment in KB medium, LOPAT tests, and utilization of different carbon sources. Genomic profiles generated with BOX-PCR placed the isolates into one groups. The results of the amplification and sequencing of the 16S rRNA, gyrB, and rpoD genes showed that the isolates belong to P. syringae pv. porri. This is the first report of the presence of the P. syringae pv. porri in Kermanshah province. Management of the disease seems to be necessary to prevent the disease epidemy.