Intersterility group differentiation in Heterobasidion annosum using ribosomal IGS1 region polymorphism

The intergenic spacer region 1 (IGS1) of the nuclear ribosomal RNA gene rep eat was examined in three European intersterility groups of the wood-rot fu ngus Heterobasidion annosum. The IGS1 elements were informative for restric tion fragment length polymorphism (RFLP) fingerprinting the fungal interste rility groups following digestion with two different four-cutter restrictio n endonucleases. The fingerprints of isolates from the same intersterility group from different localities shared some fragments in common, but also s howed specific fragments suggesting that RFLP of the IGS1 region might be u sed in population studies. RFLP patterns between isolates from different in tersterility groups differed more markedly. RFLP were also detected in the IGS1 region of North American strains of H. annosum and in the related spec ies Heterobasidion araucariae. The results indicate that ribosomal IGS1 reg ion fingerprinting could be a useful tool to identify the fungal intersteri lity group in Heterobasidion annosum.