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 the isolates were grouped into five and
three clusters at a similarity coefficient of 0.64 and 0.69, respectively. Although most of the variability
was found between isolates from different regions as expected, significant variation was observed within
the isolates collected from similar agro-ecological regions. Our results suggest the presence of different
races of R. solani within the same local geographic regions.