title: Dimorphic mating-type chromosomes in the fungus Microbotryum violaceum.
abstract: Fungi often mate as haploids, and sex chromosomes (i.e., mating-type chromosomes) that are dimorphic for their size or overall DNA content have never been reported in this kingdom. Using electrophoretic techniques for karyotype analysis, a highly dimorphic chromosome pair that determines mating compatibility is shown to occur in populations of the fungus Microbotryum violaceum. This substantiates the evolution of such dimorphism as a general feature associated with haploid determination of mating compatibility, which previously had been known only in haplodioecious plants (mosses and liverworts). Size-dimorphic sex chromosomes are present in a lineage of M. violaceum native to Europe, as well as a lineage native to North America. However, they are very different in size between these lineages, indicating either independent evolution of the dimorphism or a large degree of divergence since their isolation. Several DNA sequences that show sequence similarity to transposons were isolated from these sex chromosomes.
authors.affiliation: Department of Biology, University of Virginia, Charlottesville, Virginia 22903, USA. michael.hood@virginia.edu
authors.forename: Michael E
authors.initials: ME
authors.lastname: Hood
mesh_terms: D001487:Basidiomycota / Q000235:genetics*; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D012730:Sex Chromosomes / Q000235:genetics*