Mating factor linkage and genome evolution in basidiomycetous pathogens of cereals.
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.
Bakkeren
Guus
G
Pacific Agri-Food Research Centre, Agriculture and Agri-Food Canada, Summerland, BC. BakkerenG@agr.gc.ca
Jiang
Guoqiao
G
Warren
René L
RL
Butterfield
Yaron
Y
Shin
Heesun
H
Chiu
Readman
R
Linning
Rob
R
Schein
Jacqueline
J
Lee
Nancy
N
Hu
Guanggan
G
Kupfer
Doris M
DM
Tang
Yuhong
Y
Roe
Bruce A
BA
Jones
Steven
S
Marra
Marco
M
Kronstad
James W
JW
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*
D005656:Fungal Proteins; C402628:MFA1 protein, Ustilago hordei; D010675:Pheromones; D018626:Retroelements