ASCRIPTION OF NtISOLATES OF RHIZOCTONIA SOLANI TO ANASTOMOSIS GROUP 21 AG21 ON ACCOUNT OF rDNAITS SEQUENCE SIMILARITY
S. Kuninaga, R. Nicoletti, E. Lahoz, S. Naito
A homogeneous group of Rhizoctonia solani isolates from tobacco, which showed intermediate features between anastomosis groups BI and 2-1 (AG-BI and AG- 2-1), was recently characterized. It was not conclusively assigned to any previously known AG and was provisionally named ‘Nt-isolates’. The rDNA sequence similarity in the ITS1 region of the Nt-isolates was evaluated and a high similarity (> 90%) was found with AG-2- 1 tester isolates, while it was remarkably lower with tester isolates from AG-BI and other AG-2 subgroups. Therefore, despite a low anastomosis frequency, Nt-isolates are to be considered members of AG-2-1.