Sistotrema brinkmannii, nearly smooth, thin fruiting body in fresh state (collection Otto Miettinen 23742). [Image credit: Otto Miettinen]

In the “1KFG: Deep Sequencing of Ecologically-relevant Dikarya” project (CSP1974), we are sequencing keystone lineages of plant-interacting fungi and saprophytic fungi that are of special ecological importance for understanding terrestrial ecosystems. In addition, comparative genome analysis with saprotrophic, mycorrhizal and pathogenic fungi will provide new insights into the specific and conserved adaptations associated with each fungal lifestyle.

Sistotrema brinkmannii

Sistotrema is a highly polyphyletic genus in the order Cantharellales. The type species of Sistotrema (S. confluens) is a mycorrhizal species, but most Sistotrema species are probably not. Sistotrema brinkmannii is not closely related to the generic type but along with many other, apparently saprotrophic Sistotrema spp. forms its own lineage with the order (Moncalvo et al. 2006). Sistotrema brinkmannii is widespread and abundant, among the most common species of the genus in temperate and boreal areas of the Northern hemisphere. It forms small fruiting bodies on decaying wood and quite often on dead fruiting bodies of other wood-inhabiting fungi. Its fruiting bodies are effused, short-lived and almost smooth with minute granules.

Sistotrema brinkmannii, like most Sistotrema species, inhabits dead wood and appears to be saprotrophic, though whether they are able to decay wood is still an open question. There are no confirmed white or brown rot fungi in Cantharellales based on genomic data. Class II peroxidases are an enzyme family characteristic of white rot fungi, but so far they have not been detected in Cantharellales (Nagy et al. 2016). Understanding if members of the Cantharellales are able to decay wood and through which mechanism is a key to understanding and dating the origin of white rot - Cantharellales are the earliest diverging extant lineage of the Agaricomycetes, and all the other studied lineages of Agaricomycetes produce class II peroxidases.

Oberwinkler (1970) claims this species is lichenized, though it is unclear if his observations were based on S. brinkmannii sensu stricto. A related genus, Multiclavula, is known to be lichenized. The anamorphic genus Burgoa has been associated with Sistotrema spp. (Diederich and Lawrey 2007). The Sistotrema brinkmannii species complex has been used in studying homothallism, and it is said that bipolar, homothallic forms of this otherwise tetrapolar, heterothallic species are found in nature (Ullrich and Raper 1975; Hallenberg 1984).

The polysporic genome strain derives from a mixed forest in Helsinki, Southern Finland, where its fruiting body grew on a birch log on a dead fruiting body of Fomes fomentarius (herbarium collection Otto Miettinen 22115.1).

Researchers who wish to publish analyses using data from unpublished CSP genomes are respectfully required to contact the PI and JGI to avoid potential conflicts on data use and coordinate other publications with the CSP master paper(s).