تعيين ويژگي‌هاي جدايه‌هاي Pseudomonas syringae pv. syringae، عامل بيماري بلايت باكتريايي گندم در استان كرمان و ارزيابي واكنش ژنوتيپ‎هاي ايراني گندم نسبت به آن

Characterization of Pseudomonas syringae pv. syringae, the causal agent of bacterial blight of wheat in Kerman province and evaluation of the reaction of Iranian wheat genotypes to it

گندم نان مهم‌ترين گياه زراعي دنياست و عملكرد آن تحت تاثير بيماري‎هاي متعددي از جمله بلايت برگي باكتريايي (Bacterial leaf blight, BLB) ناشي از Pseudomonas syringae pv. syringae (Pss) قرار مي‌گيرد. مناسب‎ترين روش مديريت اين بيماري استفاده از ارقام مقاوم است. به منظور شناسايي ژنوتيپ‎هاي گندم مقاوم به اين بيماري، از بوته‌هاي گندم و جو داراي علايم مشخص بيماري بلايت در استان كرمان نمونه‌برداري و سويه‌هاي باكتري جداسازي شد. ويژگي‎هاي فنوتيپي و بيماري‌زايي جدايه‌ها تعيين و سپس با استفاده از آغازگرهاي اختصاصي ژن syrB عامل توليد سيرينگومايسين و تعيين توالي ناحيه 16S rDNA، ITS و ژن‌هاي gyrB، rpoD و hrpL ويژگي‌هاي ژنوتيپي جدايه‌ها بررسي شد. بر اين اساس دو جدايه Pss انتخاب و واكنش 99 ژنوتيپ‎ بومي بهاره و پاييزه گندم نان و دوروم (Triticum durum) نسبت به اين جدايه‎ها بررسي ‎شدند. واكنش برگ‌هاي مايه‎زني‎شده با سوسپانسيون باكتري هفت تا 10 روز پس از مايه‎زني يادداشت‎برداري ‎شد. آزمايش در قالب طرح بلوك كامل تصادفي و در سه تكرار آزمايش و هر تكرار شامل پنج بوته انجام ‎شد. نتايج اين پژوهش نشان‎داد كه از ميان ژنوتيپ‎هاي بررسي‎شده، رقم اميد به بيمارگر Pss مقاوم است. از اين ژنوتيپ گندم مي‌توان براي اصلاح ارقام مقاوم گندم به بيماري بلايت برگي باكتريايي استفاده كرد.

Wheat (Triticum aestivum) is the most important food crop in the world, but its yield is adversely affected due to plant pathogens particularly bacterial leaf blight (BLB) caused by Pseudomonas syringae pv. syringae (Pss). The management method presently in practice is insufficient to meet current safety and/or efficacy standards. Therefore, use of resistant genotypes is the best approach to manage BLB. The present study was undertaken to identify possible sources of resistance to Pss in cultivars and germplasms of wheat available. Two strains of Pss were isolated from symptomatic leaves of wheat and barley in Kerman province. The isolates were identified as Pss on the basis of physiological and biochemical characters, using specific primers and sequencing of 16S rRNA, ITS, and gyrB, rpoD, hrpL genes. Pss strains produced necrotic streaks on the susceptible wheat cv. Golestan. These strains were used for inoculation of 99 winter and spring wheat and durum (Triticum durum) genotypes to identify possible sources of resistance to BLB. The reaction of infiltrated seedlings fourth leaves infiltrated with bacterial suspension was scored seven to ten days after inoculation. Accessions were arranged in a randomized complete block design and three replications and five plants in each replicate were used. Among all the genotypes evaluated, only cv. Omid was found to be resistant to BLB. This wheat genotype can potentially be used in breeding wheat cultivars for resistance to BLB.