Use of an rRNA internal transcribed spacer region to distinguish closely related isolates of the genera Rhizoctonia

Inter-and intra specific variation among isolates of Rhizoctonia bataticola and R. solani the causal organism of root rot of cotton were evaluated by analysis of the internal transcribed spacer (ITS) sequences of the rRNA region. The ITS region was first amplified by polymerase chain reaction (PCR) with specific primers and amplification products, which ranged between 540 to 680 bp were obtained for all the isolates analyzed.The degree of polymorphism observed did not allow proper identification of most of the isolates. Analysis of two internal transcribed spacer sequences ITS 1 and ITS 2, revealed that within the isolates of R. bataticola, the size of ITS 1 region ranged from 135 to 184 bp while the size of ITS 2 varied by 4 bp. The size of ITS 1 ranged from 155 to 205 bp, while the size of ITS 2 ranged from 149 to 251 bp in isolates of R. solani. Based on phylogenetic analysis of the ITS 1 and ITS2 sequences different isolates of R. bataticola and R. solani were grouped in separate clusters.