Chapter 100 - Discussion of Teleomorphic and Anamorphic Basidiomycetous Yeasts

Abstract

The presence of ballistoconidia in Sporobolomyces led Kluyver and van Niel to suggest that this yeast is basidiomycetous, based on the morphological resemblance of ballistoconidia with actively discharged basidiospores. The life cycles of basidiomycetous yeasts include heterothallic and homothallic systems, which may occur within a single species. In the heterothallic system, compatible mating types conjugate and give rise to dikaryotic hyphae, usually with clamp connections. In many dimorphic basidiomycetes the dikaryotic hyphal state may be parasitic on either green plants or fungi. However, putative host associations have not been identified from any yeast taxa and their sexual states are only known from observations on culture media. Basidiomycetous yeasts predominantly form soft, often slimy, or mucoid colonies. The yeast state usually commences with basidiospore germination. In some Tremella species and in species of Mycogloea, basidial cells can occasionally bud directly The unicellular haploid state ends at the initiation of the dikaryotic state in those yeasts with known teleomorphs (i.e., following mating of compatible cells). However, development of hyphae and basidia from single haploid cells (i.e., self-fertile or monokaryotic fruiting) or fusion of same sex haploid cells occurs in some species, such as Filobasidiella neoformans.