Data from: The cacao pathogen Moniliophthora roreri (Marasmiaceae) possesses biallelic A and B mating loci but reproduces clonally

The cacao pathogen Moniliophthora roreri belongs to the mushroom-forming
family Marasmiaceae, but it has never been observed to produce a fruiting
body, which calls to question its capacity for sexual reproduction. In
this study, we identified potential A (HD1 and HD2) and B (pheromone
precursors and pheromone receptors) mating genes in M. roreri. A PCR-based
method was subsequently devised to determine the mating type for a set of
47 isolates from across the geographic range of the fungus. We developed
and generated an 11-marker microsatellite set and conducted association
and linkage disequilibrium (standardized index of association, IAs)
analyses. We also performed an ancestral reconstruction analysis to show
that the ancestor of M. roreri is predicted to be heterothallic and
tetrapolar, which together with sliding window analyses support that the A
and B mating loci are likely unlinked and follow a tetrapolar organization
within the genome. The A locus is composed of a pair of HD1 and HD2 genes,
whereas the B locus consists of a paired pheromone precursor, Mr_Ph4, and
receptor, STE3_Mr4. Two A and B alleles but only two mating types were
identified. Association analyses divided isolates into two well-defined
genetically distinct groups that correlate with their mating type; IAs
values show high linkage disequilibrium as is expected in clonal
reproduction. Interestingly, both mating types were found in South
American isolates but only one mating type was found in Central American
isolates, supporting a prior hypothesis of clonal dissemination throughout
Central America after a single or very few introductions of the fungus
from South America.