Identification and genetic diversity of Pseudomonas syringae pv. syringae strains causing bacterial canker in stone fruits in several northern and central provinces of Iran

Bacterial canker of stone fruits caused by Pseudomonas syringae pv. syringae (Pss) is widespread throughout Ardebil and Azarbaijane sharghi provinces. In this research samples were collected from various areas in Ardebil, Eastern Azarbaijane, Guilan, Mazandaran, Khorasane Razavi, Tehran and Qazvin provinces during 2010-2011. A total of 105 bacterial isolates were compared based on their phenotypic (physiological & biochemical) characteristics, pathogenicity and total cellular protein profiles (SDS-PAGE). Pss strains showed slight differences in phenotypic characteristics and protein profiles. All 105 strains of Pss tested were highly pathogenic on peach seedlings. All strains appeared to be similar in pathogenicity. All Pss isolates and Pss141 amplified a 752-bp fragment with the syrB primers. Genetic diversity among the strains was assessed by BOX- and IS50-PCR. Strains formed 9 and 8 clusters in the BOX-PCR and IS50-PCR, at 73% similarity level, respectively and by the combination data set of both BOX and IS50-PCR, strains formed 11 clusters. There was no significant correlation between genetic diversity and geographical origin of the isolates. The results demonstrated the existence of a considerable genetic diversity among Pss strains causing canker of stone fruit trees in various provinces of Iran. In this study, no correlation was observed between the Pss strains origin and their clusters.