فراوانی جداسازی و برخی ویژگی‌های بیماریزایی گونه‌هایی از Pseudomonas spp. عامل شانکر درختان میوه هسته دار در برخی مناطق جنوب غرب ایران

Determining the frequency of isolation of pathogens that cause a disease is an important guide for its management. Bacterial canker of stone fruit trees is caused by different bacterial species. To identify and determine the frequency of isolation, Pseudomonas spp. strains were obtained from 436 plant samples displaying typical symptoms of bacterial canker. Fruit trees sampled included peach, nectarine, apricot, plum, cherry, sour cherry and almond trees grown in some southwestern provinces of Iran, during 2018 to 2022. The isolates were identified based on a polyphasic approach which included phenotypic, biochemical and molecular tests. The frequency of isolation from the plant samples was as follows: Pseudomonas syringae pv. syringae (Pss)(32.1%), Pseudomonas syringae pv. morsprunorum (Psm)(21.8%), Pseudomonas marginalis (Pm)(10.7%), Pseudomonas viridiflava (Pv)(10.3%) and Pseudomonas syringae pv. persica (Psp) (2.7%). No bacteria were isolated from 19.3% of the samples. At least one pathogenic bacterial species was isolated from 80.7% of the samples, while 28.4% of the samples (124 samples) were infected with more than one pathogen. Pss(96%), Psm(89.5%), Psp(66.6%), Pv, and Pm(42.8%) isolates, respectively, from the highest to the lowest disease severity caused on detached branches and seedlings of the respective hosts, peach seedlings were more sensitive to all bacteria than other hosts. The frequency of isolating more than one pathogenic species was higher in orchards with severe infection. According to our information, this is the first report of Psp from Iran and of pathogenicity of Pm strains as a cause or associated with canker of stone fruit trees.