MATING-TYPE IN FILAMENTOUS FUNGI

Mating type genes regulate sexual compatibility and sexual reproductio n in fungi. This review focuses on recent molecular analyses of well-c haracterized mating systems from representative ascomycete (Neurospora crassa, Podospora anserina) and basidiomycete (Ustilago maydis, Copri nus cinereus, Schizophyllum commune) fungi. These mating systems inclu de many conserved components, such as gene regulatory polypeptides and pheromone/receptor signal transduction cascades, as well as conserved processes, like self-nonself recognition and controlled nuclear migra tion. The components' structures and their genetic arrangements in the mating system vary greatly in different fungi. Although similar compo nents and processes are also found in ascomycete yeasts (Saccharomyces cerevisiae and Schizosaccharomyces pombe), the filamentous systems ex hibit properties not encountered in yeast. Mating type genes act withi n, and control the development of, spatially differentiated fruiting b odies. The complex mating systems of basidiomycetes, unlike ascomycete systems, involve novel one-to-many specificity in both pheromone-rece ptor and homeodomain protein interactions.