شناسايي عوامل بيماري بلايت باكتريايي گياه ياس هلندي در تهران و كرج

Identification of bacterial blight disease of privet (Ligustrum sp.) in Tehran Province

طي ماه‌هاي تابستان تا پاييز سال 1396 تعداد 50 نمونه مشكوك به بيماري باكتريايي از گياه ياس هلندي از پارك­ها و فضاي سبز شهرهاي تهران و كرج جمع آوري شد. نمونه‌ها جهت بررسي­ هاي بيشتر به آزمايشگاه منتقل شد. ابتدا از نمونه‌هاي آلوده پس از شستشو و ضد عفوني سطحي با محلول 1% آب ژاول و شستشوي مجدد با آب مقطر استريل، سوسپانسيون لازم تهيه شد. سپس يك لوپ از هر سوسپانسيون روي محيط كشت­ه اي نوترينت آگار(NA) و كينگس-بي (KB) كشت گرديد. تك كلني‌هاي غالب در هر پتري ابتدا خالص سازي و سپس اثبات بيماريزايي شدند. جدايه­ هاي باكتريايي كه قادر به ايجاد فوق حساسيت روي گياه شمعداني و لكه برگي و پژمردگي روي گياه ياس هلندي بودند انتخاب شدند. از بين جدايه­ هاي منتخب، تعداد 7 جدايه كه داراي صفات فنوتيپي متفاوت از بعد صفات مرفولوژيكي، فيزيولوژيكي و بيوشيميايي بودند انتخاب شدند. با استفاده از PCR، ژن 16S rRNA جدايه­ هاي منتخب توسط جفت آغازگر عمومي P1 و P6 تكثير شدند. پس از توالي يابي محصولات PCR و بلاست توالي­ ها مشخص شد كه 7 جدايه منتخب به جنس/گونه Stenotrophomonas maltophilia، Pseudomonas plecoglossida، Staphylococcus sp.، Ochrobactrum sp.، Achromobacter sp.، Bacillus sp. و Paenibacillus sp. تعلق دارند.

During the summer months until the fall of 2017, 50 diseased samples of ligustrum plants suspected to bacterial disease were collected from all around Tehran and Karaj parks and green spaces. The diseased samples were transferred to the laboratory for further investigation. The dominant single colonies with distinguished morphology were selected and fulfilled their pathogenicity on geranium and detached stems and leaves of the host plant. Seven pathogenic bacterial isolates were further analyzed by morphological, physiological and biochemical traits. Using PCR, the 16S rRNA gene of the selected isolates was amplified DNAs were first extracted by alkaline lysis method and their 16S rRNA genes were amplified with primer pair P6/P1. The PCR products were sequenced by Macrogen Co. (Seoul, Korea) and the edited sequences were compared with deposited sequences in Genbank nucleotide database (http://www.ncbi.nlm.nih.gov). According to the results, heterogeneous species include strains of Stenotrophomonas maltophilia, strains of Pseudomonas plecoglossida, strains of Bacillus sp., strains of Paenibacillus sp., strain of Ochrobactrum sp., strains of Achromobacter sp., and strains of Staphylococcus epidermidls were identified. The presence of a wide range of not-so-well-known bacteria, but the pathogen confirms their importance, at least as secondary pathogens. This is the first report of isolating certain novel bacterial agents on ligustrum in Iran.