A phylogenetic hypothesis of Ustilaginomycotina based on multiple gene analyses and morphological data¹

Abstract

The subphylum Ustilaginomycotina comprises about 1500 species of basidiomycetous plant parasites. They are usually dimorphic, producing a saprobic haploid yeast phase and a parasitic dikaryotic hyphal phase. With only a few exceptions they occur on angiosperms and are found mainly on members of the Poaceae and Cyperaceae. Molecular methods recently have shown that anamorphic species such as members of Malassezia or Tilletiopsis should be included in this group. Here we present the most recent consensus as to the phylogeny of this group and discuss its relevant characteristics. Our morphological, ultrastructural and molecular phylogenetic data point to the existence of three lines of Ustilaginomycotina: Entorrhizomycetes, Ustilaginomycetes and Exobasidiomycetes. Entorrhizomycetes is represented by Entorrhizales, a small group of unusual teliosporic root parasites on Juncaceae and Cyperaceae. Ustilaginomycetes, to which the majority of Ustilaginomycotina belong, is a teliosporic and gastroid group characterized by the presence of enlarged interaction zones. Ustilaginomycetes is dichotomous, consisting of predominantly holobasidiate Urocystales and predominantly phragmobasidiate Ustilaginales. Exobasidiomycetes forms local interaction zones. This group is predominantly holobasidiate and consists of teliosporic Doassansiales, Entylomatales, Georgefischeriales and Tilletiales, nonteliosporic Ceraceosorales, Exobasidiales and Microstromatales, as well as the anamorphic Malasseziales. Entorrhizomycetes, Exobasidiomycetes and Ceraceosorales are proposed as new taxa, and the description of Ustilaginomycetes is emended.

• molecular phylogeny
• smut fungi
• systematics
• ultrastructure
• Ustilaginomycotina

We thank Kálmán Vánky, Apollonia Nagler, Meike Piepenbring and Franz Oberwinkler for loaning specimens; Michael Weiß for helping with the Latin diagnosis; Michael Weiß and Markus Göker for methodological advice; A. Kei Andrews for revising the language; Jacqueline Götze and Magda Wagner-Eha for technical assistance and the Deutsche Forschungsgemeinschaft for financial support. We also acknowledge support from NSF 0090301, Research Coordination Network: A Phylogeny for Kingdom Fungi to M. Blackwell, J.W. Spatafora and J.W. Taylor.