Sistotrema raduloides, close up of the fresh, hydnoid hymenophore. The genome strain derives from this collection (Otto Miettinen 20392). [Image credit: Otto Miettinen]

This genome was sequenced as part of the JGI CSP "1000 Fungal Genomes – Deep Sequencing of Ecologically-relevant Dikarya" project. Within the framework of this project, we are sequencing keystone lineages of saprophytic, mycorrhizal, and endophytic fungi that are of special ecological importance. Dozens of sequenced species were harvested from Long Term Observatories to serve as the foundation for a reference database for metagenomics of fungi and for a comprehensive survey of the soil fungal metatranscriptome.

Sistotrema raduloides OMC1660

Sistotrema is a polyphyletic, diverse genus in the order Cantharellales. The type species of Sistotrema (S. confluens) is a mycorrhizal species, but most Sistotrema species are probably not. Sistotrema raduloides represents its own lineage, separate from most other Sistotrema species (Moncalvo et al. 2006). It forms fruiting bodies on decaying decidious wood. Fruiting bodies are soft, hydnoid and effused and have a characteristic, sweet smell - among Sistotrema species this is one of the easiest to identify. Sistotrema raduloides favours closed, old forests with abundance of dead wood, and is considered associated with old-growth or high conservation value forests in North Europe. It is classified as Near Threatened in Norway.

Wheather Sistotrema raduloides and other Sistotrema species are able to decay wood is an open question. Most Sistotrema species, including S. raduloides, inhabit dead wood and appear to be saprotrophic. There are still 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, though only a few members of the order have been sequenced (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. Whether a denser sampling of the Cantharellales genomes will uncover class II peroxidases or similar enzymes remains to be seen. In any case, the genome of Sistotrema raduloides is of interest in trying to understand ecology and nutrition of early diverging Agaricomycetes.

The genome strain was collected from an old-growth forest in Southern Finland, where it grew on a fallen trunk of aspen (Populus tremula).

The 1KFG project is a large collaborative effort aiming for master publication(s). Please do contact the PI for 1KFG - Deep Sequencing of Ecologically-relevant Dikarya (Dr. Francis Martin) for permission prior to the use of any data in publications.