Diversity of Cryptococcus and Dioszegia yeasts (Basidiomycota) inhabiting arbuscular mycorrhizal roots or spores Carsten Renker a, * , Verena Blanke a , Boris B€ orstler a , Jochen Heinrichs b , Franc ßois Buscot a a Terrestrial Ecology, Institute of Botany, University of Leipzig, Johannisallee 21, D-04103 Leipzig, Germany b Department of Systematic Botany, Albrecht von Haller Institute of Plant Sciences, University of G€ ottingen, Untere Karsp€ ule 2, D-37073, G€ ottingen, Germany Received 22 September 2003; received in revised form 24 November 2003; accepted 6 January 2004 First published online 5 February 2004 Abstract The genera Cryptococcus and Dioszegia contain basidiomycetous yeasts found in a wide range of habitats. Primers to amplify the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA (nrDNA) of arbuscular mycorrhizal fungi (AMF) also allow detecting members of this yeast group. Here we report the results of a sequence analysis using maximum parsimony on a set of 50 ITS sequences of yeasts associated with AMF structures (roots of 26 plant species, AM spores) from six field sites in Central Germany. Among 10 separated taxa, respectively five in the Tremellales and two in the Filobasidiales had unknown sequences. Therefore it was not possible to assign these sequences to any known species. The study indicates that exploring the diversity of Cryptococcus and Dioszegia in soil habitats with molecular methods might enlarge the actually estimated biodiversity of the group. Ó 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved. Keywords: Arbuscular mycorrhizal fungi; Biodiversity; Cryptococcus; Dioszegia; Filobasidiales; Rhizosphere; Soil fungi; Tremellales 1. Introduction Basidiomycetous yeasts of the genus Cryptococcus have a world-wide distribution reaching from the tropics to the arctic and antarctic regions and are able to col- onize phylloplane and stems of plants [1–3], different kinds of feces [4–6], or aquatic habitats [7,8]. Recent studies have also revealed Cryptococcus as a dominating fungal group in soils [9,10]. Classical microbiological methods and physiological profiles only separate a limited number of species, but molecular techniques have shown some of them (e.g. Cryptococcus albidus and Cryptococcus laurentii) to correspond to species groups [11,12], leading to the de- scription of new taxa [13–15]. Recent studies have re- vealed the paraphyletic character of Cryptococcus that appeared to encompass species within the hymenomyc- etous Tremellales and Filobasidiales, but also some in the Trichosporonales and Cystofilobasidiales [16,17]. To solve some of the resulting taxonomic problems, the genus Dioszegia within the Tremellales was emended based on analysis of the internal transcribed spacer (ITS) of the nuclear ribosomal DNA (nrDNA), and three species, i.e. D. hungarica, D. aurantiaca and D. crocea, formerly belonging to Bullera or Cryptococcus, were designated to belong to Dioszegia [18]. In order to identify arbuscular mycorrhizal fungi (AMF) on roots by analysis of the ITS, we recently developed a nested PCR approach [19]. From its design, we knew that the primer pair for the first PCR has 100% specificity for AMF of the phylum Glomeromycota and also 100% compatibility for Basidiomycota within the Tremellales and Filobasidiales, to which Cryptococcus and Dioszegia belong. It was therefore to be expected * Corresponding author. Tel.: +49-341-973-8582; fax: +49-341-973-8599. E-mail address: crenker@uni-leipzig.de (C. Renker). 1567-1356/$22.00 Ó 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.femsyr.2004.01.001 FEMS Yeast Research 4 (2004) 597–603 www.fems-microbiology.org