Occurrence of Pseudomonas syringae pv. syringae the causal agent of bacterial canker of stone fruits in Guilan province of Iran

Abstract: Pseudomonas syringae pv. syringae causes canker, leafspots and necrosis of the bark of cherry, plum, and peach fruit trees. Symptoms caused by this pathogen on leaves, blossoms, and fruit, reported as common else where, are rare in Guilan cherry orchards. In this research, during survey from cherry, plum, and peach orchards in different areas of Guilan province (Talesh, Hashtpar, Astaneh-Ashrafieh and Lahijan), samples were taken from infected tissues of disease trees. For isolation of bacteria causing disease, infected tissue were crushed in bacteriological saline (0.85% w/v NaCl) and 100uL of juice was cultured on nutrient agar (NA) and King's B medium. Strains of bacteria rod-shaped, gram negative and aerobic bacterium were isolated. The strains produced Levan on media including sucrose. All strains made Hypersensitive Reaction (HR) on tobacco and geranium leaves. All of the isolated bacteria were oxidase, nitrate, tween 80 hydrolysis, indole and starch hydrolysis negative and could not rot potato tuber slices, produced H₂S, and grew at 36?C. The isolates could use citrate and urease. The isolates produced acid from sorbitol, galactose, myo-inositol, manitol, xylose, maltose and sucrose. Their gelatin test were positive. Based on morphological, physiological, biochemical, pathogenicity properties and total cellular protein profiles (SDS-PAGE), the predominate pathogenic type was identified as P. s. pv. syringae. This is the first report of the existence of P. s. pv. syringae on stone fruit trees in Iran.