Ustilaginomycotina sp. SA807 culture on potato dextrose agar (left) and cell morphology from potato dextrose broth (right). Bar = 2.5 mm (left) and 10 µm (right). Photos: Sebastian Albu.

Ustilaginomycetes sp. (SA807)

The ballistosporic yeast SA807 was isolated from the leaf of an aquatic fern, Salvinia molesta (giant salvinia),  in Louisiana. The fungus initially forms yeast-like colonies, but later develops a gummy or tough rubbery rugulose outer layer covered with short hyphal tufts. The culture becomes darker in color with age due to purple pigmentation that also leaches into culture media. According to molecular phylogenetic analyses and ultrastructure examination, the fungal isolate belongs to Ustilaginomycetes, but it is clearly distinct from any described orders in the class sensu Begerow et al. 2014 (Albu and Aime, unpublished).

Salvinia molesta D.S. Mitchell is an invasive free-floating aquatic fern species that forms dense mats on the surfaces of lakes and ponds. A few studies have focused on potential biocontrol methods (Flores & Carlson, 2006, Schooler, et al., 2011) . However, its fungal phylloplane ecology remains undocumented. Understanding fungal symbionts and their relationship to the plant host may lead to potential approaches for controlling Salvinia species.

The genome sequence of Ustilaginomycetes sp. SA807 will provide the genome reference sequence for a new lineage of smut fungi. Researchers will use these data in phylogenetic and phylogenomic reconstructions and in comparative genomics studies that seek to elucidate the molecular bases governing production of sexual and anamorphic states and the evolution of phytopathogenicity in Ustilaginomycotina.