Morphological and Genetical Variability among Rhizoctonia solani Isolates Causing Sheath Blight Disease of Rice

Eighteen isolates of Rhizoctonia solani collected from infected rice plants in four different locations of Bangladesh were studied by using morphological characters and molecular markers. Anastomosis study with a reference isolate confirmed that all the isolates belonged to R. solani. Significant variation was observed in sclerotial size, shape and distribution. Un-weighted pair group method with arithmetic mean dendrogram constructed based on the Gower's general similarity coefficient showed that these isolates were grouped into four clusters at the 0.68 similarity coefficent according to morphological characters. Cluster I was a major cluster consisting of 13 isolates, while clusters II to IV consisted of 1 or 2 isolates. Analyses by variable number of tandem repeat and amplified fragment length polymorphism markers showed that…