Identification of Intersterility Groups of Heterobasidion annosum by Restriction Analysis of PCR Products

Polymerase chain reaction (PCR) was used to amplify ribosomal RNA (rRNA) genes of two isolates belonging to different intersterility groups of Heterobasidion annosum. Amplification of nuclear small rRNA or small mitochondrial rRNA yielded products of similar size in both intersterility groups. Digestion of PCR products with restriction enzymes did not reveal any differences between groups. Amplification of an internal transcribed spacer (ITS) region yielded an 0.3 kb product in both isolates. Digestion of this product with Hha I restriction enzyme revealed an intersterility specific banding pattern. These results indicate that PCR has a considerable potential for the diagnosis and characterization of fungal pathogens which are difficult to identify in conventional ways.