title: Characterisation of the mating-type locus in the genus Xanthoria (lichen-forming ascomycetes, Lecanoromycetes).
abstract: Conserved regions of mating-type genes were amplified in four representatives of the genus Xanthoria (X. parietina, X. polycarpa, X. flammea, and X. elegans) using PCR-based methods. The complete MAT locus, containing one ORF (MAT1-2-1) coding for a truncated HMG-box protein, and two partial flanking genes, were cloned by screening a genomic lambda phage library of the homothallic X. parietina. The flanking genes, a homologue of SLA2 of Saccharomyces cerevisiae and a DNA lyase gene, served to amplify the two idiomorphs of the X. polycarpa MAT locus. Each idiomorph contains a single gene: MAT1-2-1 codes for a HMG-box protein, MAT1-1-1 encodes an alpha domain protein. The occurrence of mating-type genes in eight single spore isolates derived from one ascus was studied with a PCR assay. In the homothallic X. parietina a HMG fragment, but no alpha box fragment was found in all isolates, whereas in X. elegans, another homothallic species, all tested isolates contained a fragment of both idiomorphs. Conversely, isolates of the heterothallic X. polycarpa contained either a HMG or an alpha box fragment, but never both.
authors.affiliation: Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland.
authors.forename: Sandra
authors.initials: S
authors.lastname: Scherrer
authors.forename: Undine
authors.initials: U
authors.lastname: Zippler
authors.forename: Rosmarie
authors.initials: R
authors.lastname: Honegger
mesh_terms: D000595:Amino Acid Sequence; D001203:Ascomycota / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics; D015723:Gene Library; D023061:Gene Order; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal / Q000235:genetics*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013172:Spores, Fungal
chemical_list: D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D004271:DNA, Fungal; D005656:Fungal Proteins; C082266:SLA2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase