Molecular characterization of mating-type loci in selected homothallic species of Neurospora, Gelasinospora and Anixiella

Abstract

The mating-type loci of selected homothallic members of the Sordariaceae have been compared with the mating-type locus of the heterothallic Neurospora crassa . The N. crassa A mating-type idiomorph is present in its entirety in all homothallic strains tested with the exception of N. terricola , which is missing approximately 1·0 kbp. In N. crassa , this 1·0 kbp region contains an open reading frame for a polypeptide with a DNA-binding domain. Earlier mutational analyses show that this region is involved in events following fertilization. Some 700 bp of the N. crassa a idiomorph are also absent from the genomes of all homothallic strains tested. A 1·1 kbp region to the immediate left of the N. crassa mating-type locus is present in the genomes of all the homothallic species and is contiguous with the a idiomorph in most isolates. At least 2 kbp from the right flank of the N. crassa mating-type locus is not present in any of the homothallic strains tested. The absence of regions in and around the mating-type locus is discussed in light of the molecular function of the N. crassa mating-type region.