Mating genes in and evidence for a heterothallic ancestral state.

The genus includes many important plant pathogens with a wide global distribution. In order to better understand the reproductive biology of these fungi, we characterised the structure of the mating type locus and flanking genes using the genome sequences for seven species. Primers to amplify the mating type genes in other species were also developed. PCR amplification of the mating type genes and multi-gene phylogenetic analyses were used to investigate the mating strategies and evolution of mating type in a collection of 70 species residing in 10 species complexes. Results showed that the organisation of the locus and flanking genes is conserved. In heterothallic species, a novel gene, was identified in the idiomorph; the idiomorph, in most cases, contained the gene. Neither nor was found in homothallic (.) , , and . Four different homothallic locus gene arrangements were observed. Ancestral state reconstruction analysis provided evidence that the homothallic state was basal in and this evolved from a heterothallic ancestor.