تعیین گروه های آناستوموزی Rhizoctonia solani مرتبط با پوسیدگی ریشه و طوقه فلفل در ارومیه

Pepper (Capsicum annuum) is one of the most important vegetables that is cultivated in the most regions of West Azarbaijan province. Several pests and diseases reduce the quality and quantity of this crop worldwide and, root and crown rot caused by Rhizoctonia solani is considered as one of the most important diseases of pepper. In order to identify the anastomosis groups of Rhizoctonia isolates associated with this disease in the fields located in vicinity of Urmia, pepper plants showing the disease symptoms were collected from various fields in 12 regions in July to October, 2016. After washing with tap water and disinfection with 0.5% sodium hypochlorite, small pieces of root and crown from the margins of rotted parts were cultured on PDA containing streptomycin. After 48 hours, hyphae growing from plant tissues were transferred onto 2% water-agar and were then purified using hyphal tip method. In preliminary examination of morphological and colony characteristics of purified isolates, 47 R. Solani isolates was identified. To determine the anastomosis groups, pairs of Rhizoctonia isolates were first cultured on opposite sides on glass slides covered with a thin layer of PDA and after 12 hours incubation in moist chamber, isolates with the same anastomosis group were determined by examining the hyphal fusion of the isolates under microscope. Then, one isolate from each anastomosis group was selected and ribosomal ITS1-5.8S-ITS2 region of these isolates was amplified and sequenced. Overall, 47 R. solani isolates were collected from nine regions. Results of phylogenetic analyses indicated that the isolates were belonged to the three anastomosis groups i.e. AG-4, AG-5 and AG-K that AG-K is binucleate and the other two groups are multinucleate. Among the studied samples, 39 AG-4 isolates were detected in seven regions and, therefore, it was dominant anastomosis group in the pepper fields located in vicinity of Urmia. The isolates of the other two anastomosis groups were found in smaller geographical areas and lower frequencies, as six AG-5 and two AG-K isolates were detected in four and one regions, respectively.