Allozyme Differentiation of Intersterility Groups ofHeterobasidion annosumIsolated from Conifers in the Western United States

Allozyme analysis was conducted on 64 isolates from basidiocarps of Heterobasidion annosum. The isolates belonged to the «S» and «P» intersterility groups and were collected from five conifer species found in the western United States. Ten allozyme loci distributed among eight enzyme systems were examined. Intersterility groups differed at nine loci. Few alleles were common to both intersterility groups, and only one locus, MDH-1, was monomorphic. Several loci, including MDH-2, GDH, and PGI, were diagnostic for the S or P intersterility groups, suggesting fixation for alternative or null alleles (...)