Detection of rDNA ITS polymorphism in Rhizoctonia solani AG 2-1 isolates

Abstract

The sequence variability of the ribosomal internal transcribed spacer regions ITS1 and ITS2, including the 5.8S gene, was investigated for Rhizoctonia solani isolates of anastomosis group (AG) 2-1. During PCR RFLP analysis of eight isolates, the restriction patterns of four isolates showed an excess of bands after restriction with the enzymes AvaII and/or HincII, which suggested the presence of more than one ITS region. By cloning the ITS region of six isolates sequence heterogeneity was detected in the isolates that showed an excess of bands in the PCR RFLP analysis; up to nine different ITS regions were identified within one isolate. The same level of diversity was found within the same isolate as among isolates. In the phylogenetic tree based on the rDNA ITS sequences of several AG 2-1 isolates, sequences derived from the same isolate did not form distinct clusters, questioning the relevance of further subdivision of heterogeneous AG 2-1 isolates based on the ITS region.

• anastomosis group 2-1
• internal transcribed spacer
• ITS heterogeneity
• Thanatephorus cucumeris

The authors thank Orelvis Portal for his helpful advice and technical comments during this work. Financial support for this research was provided by a grant to Joke Pannecoucque from the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT-Vlaanderen).