Ein Beitrag zur Systematik und Entwicklungsbiologie höherer Pilze: Hefe-Typen der Basidiomyceten. Teil II: Microbotryum-Typ

In this and three further papers 205 yeasts and yeast states of Basidiomycetes and presumed relatives were investigated comparatively on the basis of the carbohydrate (neutral sugars) pattern of purified cell walls, urease-activity, diazonium blue B reaction on the production of extracellular amyloid compounds (EAS), fermentation of carbohydrates, and ubiquinone data. A clustering leading to the Protomyces-, the Microbotryum-, the Ustilago-, the Dacrymyces-, and the Tremella-type became apparent, especially from the qualitative and quantitative cell wall carbohydrate pattern. The different yeast types correspond well with 5S rRNA clusters known from the literature. 31 strains clustering within the Microbotryum-type comprise the phragmobasidial smut fungi of dicotyledonous hosts (Microbotryum. Sphacelotheca), the phragmobasidial Rhodosporidium- and Leucosporidium-species including some anamorph Rhodotorula-species, which lack an oxidative degradation of myo-inositol, the genera Sporobolomyces and Sporidiobolus, the Septobasidiales and some simple septate Auriculariales e.g. Agaricostilbum, Platygloea. Main characteristics of the Microbotryum-type are: 1. The absence of extracellular amyloid compounds. 2. The dominance of mannose and the presence of fucose as cell wall constituents. 3. A positive DBB-reaction and splitting of urea. Four Ustilago species parasitic on dicotyledonous hosts were transfered to Microbotryum (M. scabiosae, M. scorzonerae, M. cordae, M. vinosum) as a consequence from cell wall carbohydrate composition, production of rhodotorulic acid, and 5S rRNA sequence data from the literature. The predominance of mannose in the cell wall — otherwise only known from ascomycetous yeasts –, a type A secondary structure of 5S rRNA, a simple unifactorial mating system in all parasitic smut species suggest that the Microbotryum-type might be ancestral to the Ustilago-type. An evolution of simple (“siphonal”) holobasidia from “pseudotrichal” phragmobasidia will be discussed.     

Graphiolales: Basidiomycetes parasitic on palms

Graphiola phoenicis was restudied by light microscopy and investigated in detail with the scanning and the transmission electron microscopes. Hyphae of the fruitbody are mainly dikaryotic. Karyogamy occurs in cells which are interpreted as meiosporangia (basidia), and which develop in chains. Shortly after karyogamy, meiosis takes place in these basidia. Primary, sessile meiospores are then formed which later divide and produce thick-walled diaspores. The latter germinate either by hyphae or by yeast-like budding. The nutritional requirements of pure cultures of the yeast stage were also investigated. Life cycle, karyological criteria, ultrastructural details, and chemical tests clearly show thatGraphiola belongs in theBasidiomycetes. The taxonomic position within theHeterobasidiomycetes is discussed and the orderGraphiolales is validated.