La. Casselton et Ns. Olesnicky, MOLECULAR-GENETICS OF MATING RECOGNITION IN BASIDIOMYCETE FUNGI, Microbiology and molecular biology reviews, 62(1), 1998, pp. 55
The recognition of compatible mating partners in the basidiomycete fun
gi requires the coordinated activities of two gene complexes defined a
s the mating-type genes. One complex encodes members of the homeobox f
amily of transcription factors, which heterodimerize on mating to gene
rate an active transcription regulator. The other complex encodes pept
ide pheromones and 7-transmembrane receptors that permit intercellular
signalling. Remarkably, a single species may have many thousands of c
ross-compatible mating types because the mating-type genes are multial
lelic. Different alleles of both sets of genes are necessary for matin
g compatibility, and they trigger the initial stages of sexual develop
ment-the formation of a specialized filamentous mycelium termed the di
karyon, in which the haploid nuclei remain closely associated in each
cell but do not fuse. Three species have been taken as models to descr
ibe the molecular structure and organization of the mating-type loci a
nd the genes sequestered within them: the pathogenic smut fungus Ustil
ago maydis and the mushrooms Coprinus cinereus and Schizophyllum commu
ne. Topics addressed in this review are the roles of the mating-type g
ene products in regulating sexual development, the molecular basis for
multiple mating types, and the molecular interactions that permit dif
ferent allelic products of the mating type genes to be discriminated.
Attention is drawn to the remarkable conservation in the mechanisms th
at regulate sexual development in basidiomycetes and unicellular ascom
ycete yeasts, Saccharomyces cerevisiae and Schizosaccharomyces pombe,
a theme which is developed in the general conclusion to include the fi
lamentous ascomycetes Neurospora crassa and Podospora anserina.