Enigmatic Sebacinales

A historical retrospect and a taxonomic update will deal with Sebacina s.l. and s.str., Craterocolla, Efibulobasidium, Serendipita, Tremellodendron, Tremelloscypha, Tremellostereum, and Piriformospora, the Sebacinaceae, and the Sebacinales. Phylogenetic hypotheses for the order and subordinal taxa are discussed, including environmental sequence taxa. The cryptic biodiversity in Sebacinales is extensive but mostly unresolved with respect to the species involved. Trophic stages are manifold in Sebacinales but restricted to plant dependencies. Most of the species grow endophytically or form various mycorrhizae, but Craterocolla and Efibulobasidium species appear to be saprobic. The sebacinalean mycorrhizal diversity is unparalleled: ectomycorrhizae, ericoid and orchid mycorrhizae are frequent, both in autotrophs and heterotrophs, as well as mycothalli with Jungermanniales. Mycorrhizal community structures are difficult to evaluate in Sebacinales because of the high percentage of environmental sequence taxa lacking further characteristics. Nutritional requirements and exchanges have been studied extensively in Piriformospora indica, suggesting future possibilities for agricultural applications. The genomes of this species and of Sebacina vermifera have been sequenced recently, thus opening new fields in studying and understanding functional and evolutionary aspects.