F. floriforme cells (photo credit: Minou Nowrousian)

Filobasidium floriforme

Filobasidium floriforme is a basidiomycete belonging to the order Filobasidiales within the Tremellomycete group. In contrast to many mushroom-forming basidiomycetes, F. floriforme grows mostly as a yeast, i.e. as single cells as can be seen in the picture, or forming few filamentous structures (hyphae). F. floriforme is capable of accumulating trehalose, a disaccharide that is used in a variety of fields for its preservative properties. Thus, F. floriforme is a candidate for the analysis of biochemical pathways that enable the biosynthesis and accumulation of trehalose. In addition, the Tremellomycete group of basidiomycetes, of which F. floriforme is a member, is of interest for the analysis of the evolution of sexual development, in particular of the mating-type regions. This has been studied in detail in the order Tremellales that comprises model organisms like the human pathogen Cryptococcus neoformans, and these analyses have indicated a trend towards fusion of the two mating type loci into one large mating-type region in pathogenic Cryptococci. A similar trend was recently observed in the Trichosporonales, a sister order to the Tremellales. However, it is not clear yet how widespread this trend is and if it extends to other branches of Tremellomycetes and therefore might constitute an ancient evolutionary trait. Thus, the genome of F. floriforme will be informative with respect to the evolution of sexual development in fungi.