Molecular standardization of mating type terminology in the Gibberella fujikuroi species complex

Mating type in the Gibberella fujikuroi species complex is controlled by a single locus with two alleles and is usually identified following sexual cr osses with standard, female-fertile tester isolates. The mating type allele s have been arbitrarily designated "+" and "-" within each biological speci es, and the nomenclature is tied to the standard tester strains. We develop ed a pair of PCR primers that can be used to amplify a unique fragment of o ne of the mating type alleles (MAT-2) from at least seven of the biological species in this species complex. Based on the amplification pattern, we pr opose a replacement for the existing, arbitrary +/- terminology that is pre sently in use. The new terminology is based on DNA sequence similarities be tween the mating type allele fragments from the biological species of the G . fujikuroi species complex and the corresponding fragments from other fila mentous ascomycetes.