SUITABILITY OF INTERGENIC SPACER OR INTERNAL TRANSCRIBED SPACER MICROSATELLITE-PRIMED PCR FOR THE IDENTIFICATION OF RHIZOCTONIA SOLANI AND SOME PHYTOFUNGI

The intergenic spacer (IGS) region or internal transcribed spacer (ITS) region were used in pair-combinations with microsatellite-primed polymerase chain reaction (MP-PCR) primers to establish whether additional polymorphisms can be yielded. A total of 24 Rhizoctonia solani isolates representing 13 anstomosis groups and 9 different fungal species isolate were recovered from different areas and hosts. Forty different primer combinations were tested for their ability to provide discrete bands and individual isolates' readily interpretable and reproducible IGS / ITS-MP-PCR profiles. Both approaches produced highly reproducible and complex genomic fingerprints, with fragments ranging in size from 100 to 2,000 bp (IGS-MP-PCR) and 50 to 2,000 bp (ITS-MP-PCR). MP-PCR markers yielded more bands than IGS / ITS-MP-PCR because of their higher redundancy in the fungal genome. The number of fragments generated by both techniques varied according to the fungal species and also with the primer combination used. Each primer used could differentiate all of the fungal isolates examined in this study. The profiles generated were identical and reproducible between repeated PCR experiments.

PRACTICAL APPLICATIONS

Combining the intergenic spacer/internal transcribed spacer-microsatellite-primed polymerase chain reaction technique with microsatellite–detection assay allows the rapid and specific detection of Rhizoctonia solani anastomosis groups and different phytopathogenic fungi. The utility of this approach stems from its simplicity and reproducibility, the high number of polymorphisms revealed, the very small amounts of DNA needed, rapidity, and ease of performance. The improved technique will present valuable information on the role of some phytopathogenic fungi and R. solani in agriculturally important plant diseases.