Leaf-inhabiting endophytic yeasts are abundant but unevenly distributed in three Ficus species from botanical garden greenhouses in Germany

Yeasts of both Ascomycota and Basidiomycota occur in various ecological zones of many geographic regions and climatic conditions, but environmental yeast research has often been conducted in either extreme habitats or the phyllosphere. Here, we report on the occurrence of foliar endophytic yeasts of three tropical Ficus species from two German greenhouses in Greifswald and Berlin. Living leaves were collected and subjected to dilution-to-extinction cultivation. Fungal colonies were used for morphological analyses, microsatellite-primed fingerprinting, sequencing and phylogeny of the internal transcribed spacer (ITS) DNA. Fifteen percent (similar to 200 colonies) of all fungal isolates belonged to the genera Cryptococcus (Filobasidiales) and Rhodotorula (Sporidiobolales and Cystobasidiales) that split into 23 species / operational taxonomic units. No other yeast-forming taxa were isolated. Both side-specific and host-specific variations in species composition and abundance were observed; however, statistics did not support significant associations. Further evidence exists that gardening practices, such as moving potted plants, could influence fungal endophytic communities.