Genome biology and evolution of mating-type loci in four cereal rust fungi

by Zhenyan Luo, Alistair McTaggart, Benjamin Schwessinger Permanent heterozygous loci, such as sex- or mating-compatibility regions, often display suppression of recombination and signals of genomic degeneration. In Basidiomycota, two distinct loci confer mating compatibility. These loci encode homeodomain (HD) transcription factors and pheromone receptor (Pra)-ligand allele pairs. To date, an analysis of genome level mating-type (MAT) loci is lacking for obligate biotrophic basidiomycetes in thePucciniales, an order containing serious agricultural plant pathogens. Here, we focus on four species ofPuccinia that infect oat and wheat, includingP.coronata f. sp.avenae,P.graminis f. sp.tritici,P.triticina andP.striiformis f. sp.tritici. MAT loci are located on two separate chromosomes supporting previous hypotheses of a tetrapolar mating compatibility system in thePucciniales. TheHD genes are multiallelic in all four species while the PR locus appears biallelic, except forP.graminis f. sp.tritici, which potentially has multiple alleles. HD loci are largely conserved in their macrosynteny, both within and between species, without strong signals of recombination suppression. Regions proximal to the PR locus, however, displayed signs of recombination suppression and genomic degeneration in the three species with a biallelic PR locus. Our observations support a link between recombination suppression, genomic degeneration, and allele diversity of MAT loci that is consistent with rece...
Source: PLoS Genetics - Category: Genetics & Stem Cells Authors: Source Type: research