ETIOLOGY AND HOST RANGE OF BACTERIAL LEAF BLIGHT AND NECROSIS OF SQUASH AND MUSKMELON IN IRAN
N. Sedighian, M. Shams-Bakhsh, E. Osdaghi, P. Khodaygan
In Summer and Autumn of 2010, blighted cucurbitssuspected of bacterial infection were observed in the EastAzarbayejan province of Iran. Infected plants exhibitedspots on the leaves which, in the early stages of the disease,appeared as small, yellow and water-soaked with chlorotichaloes. As time went by, the spots enlarged, necrotizedand coalesced so as to cover a large area of the blade,while the leaves rolled along their longitudinal axis. Suchsymptoms had not previously been observed in cucurbitsin East Azarbayejan. To investigate the etiology of thisdisorder, symptomatic leaves were collected from affectedplants and the putative agent was isolated and identified asPseudomonas syringae pv. aptata based on morphological,physiological, biochemical, molecular and pathogenicitytests. In BOX-PCR, four bacterial isolates from cucurbitsformed a coherent group and their sequences showed ahigh similarity (99%) with P. syringae pv. aptata GSPB1067,as confirmed by phylogenetic analysis based on gyrB andrpoD. To the best of our knowledge, this is the first reportof leaf blight and necrosis of Cucurbitaceae causedby P. syringae pv. aptata in Iran.