Anastomosis Grouping of Rhizoctonia solani Isolates Causing Rice Sheath Blight Disease in Andhra Pradesh, India

Thirty isolates of Rhizoctonia solani collected from different regions across five districts of Andhra Pradesh were observed for variation and identification of anastomosis group causing sheath blight of rice in Andhra Pradesh. The hyphal anastomosis test results indicated that all the isolates belong to single anastomosis group AG1-1A. Further, anastomosis reactions were grouped into three categories. YSR Kadapa isolates showed C1: hyphae contact only (same/different AG), Nellore and Chittoor isolates showed C2: killing reaction which represents a vegetative incompatibility response between genetically different individuals (same AG), West and East Godavari isolates have shown C3: perfect fusion (same AG) of vegetative hyphal cells between two isolates that suggestive of genetically similar. The distribution pattern of AG categories in different districts of Andhra Pradesh found the correlation with geographical region where the pathogen isolate was collected and the data also correlated with the genetic variation analysis where the grouping of isolates were based on geographical origin.