title: Ancestral polymorphism and linkage disequilibrium at the het-6 region in pseudohomothallic Neurospora tetrasperma.
abstract: In species of Neurospora, non-self recognition is mediated by at least 11 heterokaryon (het) incompatibility loci. Previously, we identified ancient allelic variation at het-c in pseudohomothallic N. tetrasperma, which confirmed outcrossing in this species. Here, we report distinct ancestral alleles at het-6 and un-24, two closely linked genes with het incompatibility function in N. crassa. The pattern of variation at het-6 and un-24 in N. tetrasperma is similar to that observed for N. crassa, where two ancestral allele specificities exist for each locus, Oak Ridge (het-6(OR), un-24(OR)) and Panama (het-6(PA), un-24(PA)). Only het-6(OR)/un-24(OR) and het-6(PA)/un-24(PA) allele combinations have been observed. The absence of recombinant haplotypes (e.g., het-6(OR)/un-24(PA)) appears to derive from an ancestral chromosomal rearrangement that limits recombination. Allelic variation at het-6 and un-24 in N. tetrasperma provides further evidence of outcrossing in this predominantly selfing species and indicates that selection maintains ancient allelic diversity at het loci.
authors.affiliation: Department of Plant Pathology, North Carolina State University, Campus Box 7244, Raleigh, NC 27695-7244, USA. Amy.Powell@duke.edu
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Powell
authors.forename: David J
authors.initials: DJ
authors.lastname: Jacobson
authors.forename: Donald O
authors.initials: DO
authors.lastname: Natvig
mesh_terms: D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D049770:Genes, Mating Type, Fungal; D014644:Genetic Variation; D015810:Linkage Disequilibrium; D009491:Neurospora / Q000235:genetics* / Q000502:physiology; D011995:Recombination, Genetic
chemical_list: D005656:Fungal Proteins