Molecular and Conventional Identification and Pathogenicity of Rhizoctonia solani Isolates from Tobacco (Nicotiana tabacum L.) in Samsun, Turkey

Abstract

A total of 101 fungal samples were isolated from tobacco (Nicotiana tabacum L.) plants in Samsun, Turkey and identified as Rhizoctonia solani. Of these samples, three were identified as belonging to Anastomosis Group (AG) -1-IB, 6 to AG-2-1, 25 to AG-4-HG-I and 67 to AG-4-HG-II, using ITS1-5.8S-ITS2 rDNA RFLP analysis, base sequence phylogenies and conventional characters, such as anastomosis reactions, morphology and thiamine requirement. For five isolates from both the AG-4-HG-I and AG-4-HG-II groups and for all isolates of the AG-1-IB and AG-2-1 groups, molecular analysis and pathogenicity tests were performed. All selected Rhizoctonia solani isolates were highly virulent to tobacco plants, causing symptoms resembling damping-off, except for isolate 55TkTB63, which was only moderately virulent.