بررسی عوامل مولد شانکر درختان میوه هسته دار در استان قم

Stone fruit canker disease is produced by some pseudomonas species and pathovars of P.syringae. some yeast species have in recent years been encountered associated with or causing stem canker in a few central and khorasan provinces of Iran. To determine the microorganisms associated with canker symptoms in Qom province, the regions were surveyed and symptomatic specimers were collcted and brought to the laboratory. Pieces of shoots with canker symptoms were washed under tap water and the affected bark tissues were macerated in drops of sterile water in petri dishes . After30 min standing at room temperature, loopfals of the resulting suspensions were streaked on plates of sucrose nutrient agar (SNA). single whitish to pale pink colonies growing on the medium after two days of incubation at 25C were subcaltured on SNA. Phenotypic characteristics the isolates were determined using standard bacteriological method . selected isolates were inoculated by wounding on twig of peach(Prunus persica) seedling. Brown sunken lesions were formed on twig about 12 days post inoculation. The inoculated isolates werereisolated from the cankered tissuees . some cankers were cracked but did not exude gummy sahstance . Isolats were urease positive, oxidase negative and tolerated 4% sodium chloride. They atilized several carbo hydrates including sucrose trehalose xylose and citrate but not inulin, mesoeryth rifol melibiose or galacturonate as sole carbon sources for growth . Genomic DNA was isolated from selected strainsand used for PCR amplification of a frogment of the 26S rRNA, using primers D1D2. The amplicons were sequenced (by bioneer company in soth korea ). The sequences were companed with those prent in Gen Bank using the BLAST algorithm . The isolates showed the highest similarity with Cryptococcus friedmanni. No pathogemic pseudomonas species were isolated from the samples tested.