Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 20, 1999
Publication Date: N/A
Technical Abstract: Yeasts occur in both the Ascomycota and the Basidiomycota, but their placement within each of these phyla has only become apparent in recent years as a result of phylogenetic analysis of gene sequences such as ribosomal DNA. From this work, the budding ascomycetous yeasts were shown to be a sister group to the euascomycetes, whereas Schizosaccharomyces, Taphrina, Protomyces, Saitoella, Neolecta, and Pneumocystis represent a phylogenetically divergent group basal to the other ascomycetes. Basidiomycetous yeasts occur in four phylogenetic groups that are represented by Sympodiomycopsis, Rhodosporidium, Filobasidiella, and Cystofilobasidium. Molecular studies are beginning to provide an accurate means for resolution of species and for their rapid detection. These studies have also demonstrated that many presently accepted genera are poorly circumscribed, primarily because morphology-based taxonomic characters, such as ascospore shape, presence of teliospores in meiotic states, and hyphal septal structure, often correlate poorly with relationships determined from phylogenetic analysis of gene sequences. The impact of molecular studies on yeast taxonomy and on estimates of biodiversity will be discussed.