THE ROLE OF NUCLEOTIDE-SEQUENCE ANALYSIS IN THE SYSTEMATICS OF THE YEAST GENERA CRYPTOCOCCUS AND RHODOTORULA

Phylogenetic relationships of basidiomycetous yeasts and yeast-like or ganisms were studied using partial large-subunit ribosomal DNA and RNA sequences. Three main clusters could be distinguished, which correspo nd with the orders Sporidiales, Tremellales and Ustilaginales, and cor relate with the biochemical composition of the cell wall and septal ul trastructure. Among the Sporidiales (Rhodotorula, Rhodosporidium, Spor obolomyces, Sporidiobolus) several clades are apparent, which also con tain some species of Erythrobasidium, Bensingtonia, Leucosporidium and Microbotryum. This indicates that these yeasts are polyphyletic. A si milar phylogenetic diversity was found among the Tremellales and Ustil aginales. Additionally, the results demonstrate that phenetic characte rs are not always reliable indicators for a phylogenetic classificatio n. A PCR technique for species identification is discussed.