title: Mating factor linkage and genome evolution in basidiomycetous pathogens of cereals.
abstract: Sex in basidiomycete fungi is controlled by tetrapolar mating systems in which two unlinked gene complexes determine up to thousands of mating specificities, or by bipolar systems in which a single locus (MAT) specifies different sexes. The genus Ustilago contains bipolar (Ustilago hordei) and tetrapolar (Ustilago maydis) species and sexual development is associated with infection of cereal hosts. The U. hordei MAT-1 locus is unusually large (approximately 500 kb) and recombination is suppressed in this region. We mapped the genome of U. hordei and sequenced the MAT-1 region to allow a comparison with mating-type regions in U. maydis. Additionally the rDNA cluster in the U. hordei genome was identified and characterized. At MAT-1, we found 47 genes along with a striking accumulation of retrotransposons and repetitive DNA; the latter features were notably absent from the corresponding U. maydis regions. The tetrapolar mating system may be ancestral and differences in pathogenic life style and potential for inbreeding may have contributed to genome evolution.
authors.affiliation: Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, Summerland, BC. BakkerenG@agr.gc.ca
authors.forename: Guus
authors.initials: G
authors.lastname: Bakkeren
authors.forename: Guoqiao
authors.initials: G
authors.lastname: Jiang
authors.forename: René L
authors.initials: RL
authors.lastname: Warren
authors.forename: Yaron
authors.initials: Y
authors.lastname: Butterfield
authors.forename: Heesun
authors.initials: H
authors.lastname: Shin
authors.forename: Readman
authors.initials: R
authors.lastname: Chiu
authors.forename: Rob
authors.initials: R
authors.lastname: Linning
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Schein
authors.forename: Nancy
authors.initials: N
authors.lastname: Lee
authors.forename: Guanggan
authors.initials: G
authors.lastname: Hu
authors.forename: Doris M
authors.initials: DM
authors.lastname: Kupfer
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Tang
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Roe
authors.forename: Steven
authors.initials: S
authors.lastname: Jones
authors.forename: Marco
authors.initials: M
authors.lastname: Marra
authors.forename: James W
authors.initials: JW
authors.lastname: Kronstad
mesh_terms: D002523:Edible Grain / Q000382:microbiology*; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000235:genetics*; D049770:Genes, Mating Type, Fungal; D008040:Genetic Linkage; D016681:Genome, Fungal; D010675:Pheromones / Q000235:genetics*; D020161:Physical Chromosome Mapping; D010935:Plant Diseases / Q000382:microbiology*; D018626:Retroelements / Q000235:genetics; D019849:Sex Determination Processes; D020080:Tandem Repeat Sequences; D014588:Ustilago / Q000235:genetics*
chemical_list: D005656:Fungal Proteins; C402628:MFA1 protein, Ustilago hordei; D010675:Pheromones; D018626:Retroelements