A phylogenetic study of the genus Tilletiopsis, Tilletiaria anomala and related taxa based on the small subunit ribosomal DNA sequences.

Abstract

Small subunit ribosomal RNA gene sequences were determined in six species of the genus Tilletiopsis, in addition to Tilletiaria anomala. The phylogenetic trees were constructed for the species of the genus Tilletiopsis, in addition to T. anomala and related taxa by neighbor-joining and maximum likelihood methods. The phylogenetic trees showed that the basidiomycetous yeasts and related taxa were divided into three main clusters. Six species of the genus Tilletiopsis, in addition to T. anomala, constituted a cluster with Sympodiomycopsis paphiopedili, Tilletia caries, Ustilago hordei and U. maydis (cluster 1). In cluster 1, Tilletiopsis species and T. anomala constituted a subcluster with S. paphiopedili and T. caries (cluster 1b). The reliability of cluster lb was statistically well supported. On the other hand, Sporobolomyces roseus, the type species of the genus Sporobolomyces, was located at cluster 2 together with Bensingtonia species, Erythrobasidium hasegawianum, Kondoa malvinella, Leucosporidium scottii, Rhodosporidium toruloides and Sporidiobolus johnsonii. This result clearly showed the phylogenetic divergence between the genera Tilletiopsis and Sporobolomyces; whereas the genera Tilletiopsis and Sporobolomyces have common chemotaxonomic characteristics, i.e., the lack of xylose in the cells and the possession of Q-10 as the major ubiquinone.