Journal of Phytopathology. 2018;1–9. wileyonlinelibrary.com/journal/jph | 1 © 2018 Blackwell Verlag GmbH 1 | INTRODUCTION Pseudomonas syringae is a pathogen of over 180 plant species in- cluding fruit trees (Agrios, 2005). Because of differential pathogenic abilities, strains of P. syringae are classified into over 50 pathovars differing in range of hosts, that is species or cultivars (Young et al., 1996). Pathovars syringae (Pss), pathogenic to all commercially grown Prunus species and many other hosts and belonging to ge- nomospecies 1(reference) and morsprunorum (Psm) comprising race 1, pathogenic to cherry, plum and apricot and belonging to genom- ospecies 2 (Wormald, 1932), and race 2, pathogenic to cherry be- longing to genomospecies 3 (Freigoun & Crosse, 1975) are the main causal agents of bacterial canker and gummosis on stone fruit trees (Bultreys & Kaluzna, 2010; Burkowicz, 1981; Gardan et al., 1999; Sobiczewski, 1984; Vicente, Roberts, Russell, & Alves, 2004; Young, 1991). Moreover, from some species of stone fruits, pathovars avii (belonging to genomospecies 3, pathogenic to wild cherry trees grown for wood production) and persicae (belonging to genomospe- cies 3, pathogenic to peach, nectarine and Japanese plum) were iso- lated (Menard, Sutra, Luisetti, Prunier, & Gardan, 2003; OEPP/EPPO, 2005; Young, 1988). In west Azerbaijan of Iran, disease symptoms on peach, plum, almond, apricot, sweet and sour cherry plants include canker de- velopment on shoots and at the base of spurs and its progression upward accompanied by gum exudation early in the growing sea- son. Losses can result from a direct reduction in yield due to cold- induced blast or death of buds and flowers or from tree decline and death due to the development of cankers in branches and major scaffold limbs (Ogawa & English, 1991). Identification and differentiation of P. syringae pathovars were reported by Garrett, Panagopoulos, and Crosse (1966), Little, Bostock, and Kirkpatrick (1998), Scortichini, Marchesi, Dettori, and Rossi (2003), Stead Received: 14 February 2018 | Accepted: 12 April 2018 DOI: 10.1111/jph.12713 ORIGINAL ARTICLE Characterization and genetic diversity of Pseudomonas syringae isolates from stone fruits in north-western Iran Fardin Nosratnezhad 1 | Kiomars Rouhrazi 1 | Nabi Khezrinezhad 2 1 Department of Agriculture, Malekan branch, Islamic Azad University, Malekan, Iran 2 Department of Plant Protection, Mahabad Branch, Islamic Azad University, Mahabad, Iran Correspondence Kiomars Rouhrazi, Department of Agriculture, Malekan branch, Islamic Azad University, Malekan, Iran. Email: kiomars_rouhrazi@yahoo.com Abstract From 33 Iranian fluorescent Pseudomonas isolates originating from symptomatic tis- sues of peach (Prunus persica), plum (Prunus domestica), sweet (Prunus avium) and sour cherry (Prunus cerasus), 27 were identified as Pseudomonas syringae using LOPAT tests. Further characterization of those isolates by GATTa and L-lactate utilization tests and the detection of syringomycin and coronatine and yersiniabactin coding genes showed that five of them belonged to race 1 and four to race 2 of P. syringae pv. morsprunorum (Psm) and eighteen other isolates were identified as P. syringae pv. syringae (Pss). Based on the analysis of the fingerprint patterns generated by REP, ERIC and BOX-PCR, the strains were differentiated into three main groups at the 67% similarity level. Strains of the groups 1, 2 and 3 belong to Psm race 1, Psm race 2 and Pss, respectively. Rep-PCR analysis showed high intra-pathovar variation within the Pss isolates, which grouped into four distinct clusters. Using the REP primers, the percentage of polymorphic loci was 74.61%, whereas with BOX and ERIC primers, it was 60.5 and 55.21%, respectively. Finally, this study is the first report of the isola- tion of P. syringae pv. morsprunorum race 1 and 2 strains from stone fruit trees in Iran. KEYWORDS Iran, Pseudomonas syringae pv. morsprunorum, Pseudomonas syringae pv. syringae, Rep-PCR, Stone fruit trees