Molecular and pathological characterization of the isolates of Rhizoctonia spp. associated with dry bean ( Phaseolus vulgaris ) in Türkiye

A total of 65 isolates of Rhizoctonia spp. were isolated from necrotic roots of 425 symptomatic bean ( Phaseolus vulgaris ) plants collected from nine provinces of Türkiye including Balıkesir, Burdur, Bursa, Eskişehir, Karaman, Konya, Kütahya, Nevşehir and Niğde in 2018 and 2019. Fifty isolates with multinucleate (MN) hyphae were characterized as Rhizoctonia solani , whereas fifteen isolates were Rhizoctonia sp. with binucleate (BN) hyphae. The isolates of R. solani belonged to 7 anastomosis groups including AG-1 (one isolate), AG-1-IA (one isolate), AG-2-1 (six isolates), AG-4-HGI (18 isolates), AG-4-HGII (17 isolates), AG-4-HGIII (five isolates) and AG-5 (one isolate). Only one isolate could not be placed in any recognised anastomosis group. Three of these anastomosis groups, AG-1, AG-1-IA and AG-2-1, were non-pathogenic while the others caused disease severities between 71-100% on bean plants in pathogenicity tests. Fifteen BN Rhizoctonia isolates belonged to the two anastomosis groups AG-F (seven isolates) and AG-K (eight isolates). Eighty-two bean lines comprising most of the cultivars grown in Türkiye and several lines archived at Eskişehir Transitional Zone Agricultural Research Institute were tested against one of the most aggressive isolates of AG4-HGII. Four bean lines [Weighing (Samsun), USWK-6, Beryl/Weihing 1, 4F-675-1/Ph.coch.(GÖYNÜK)/Matterhorn] were resistant, while six lines [4F-2409/İTAŞ GB-33, Şeker Fasulye 2 (Sakarya/Geyve Pazardan), ES-855/4F-2834//4F-2666/4F-2849-2, (4F-1182/4F-2833)/Emerson, USCR-9, Weihing//4F-675-1/Ph.coch.(GÖYNÜK)/3/Weihing 1] were moderately resistant.