Chondrostereum purpureum fruiting bodies have a white upper surface while the lower, spore-producing surface is light-brown to purple to reddish. Photo from a birch stump, Helsinki, Finland (collection Miettinen 19107). [Photo 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.

Chondrostereum purpureum

Chondrostereum purpureum is a wood-inhabiting basidiomycete with stereoid fruiting bodies, i.e. caps with a smooth hymenial surface. It belongs to the Agaricales, in Cyphellaceae (Vizzini et al. 2022). The species is a fast-growing pioneer wood decomposer on various angiosperm wood, and can attack living trees through wounds (Rayner and Boddy 1988). After initial dominance and only limited wood decay, it gets replaced in a few years by other wood decomposing basidiomycetes. In fruit trees, particulary of Rosaceae, it causes so-called silver leaf disease (van Zoeren and McManus 2021).

C. purpureum is widely distributed in temperate and boreal regions of Eurasia and North America, and is also found in New Zealand. It shows considerable genetic variation, but no evidence of reproductive barriers has been found nor is the genetic variation structured by geography or host tree (Ramsfield et al. 1996; Becker et al. 2004; Hamberg et al. 2018).

Due to its pathogenic ability, researchers in Canada and Europe have developed a method to use it as a biocontrol agent preventing growth of unwanted deciduous tree sprouts after logging or forest clearance. Stumps of deciduous trees and saplings are treated with Chondrostereum, which kills them in a year or two, while uncut trees (and conifers) are not affected (Wall 1990; Becker et al. 2005; Hamberg et al. 2021). Its pathogenic mechanism has been studied, though it is not fully understood - polygalacturonases, laccases and peroxidase activities are associated with the infection (Hamberg et al. 2021).

Reina et al. (2019) published a genome of C. purpureum based on a German strain originating from birch wood. Based on the enzymatic profile, they concluded the species is a white-rot fungus. Laccases in particular are numerous. The genomes of this commercially and ecologically important fungus can be used to study pathogenecity, intraspecific genetic variation, as well as evolution of wood decomposition.

The current genome is based on a polysporic culture OMC 1767 from boreal central Finland (Jyväskylä), where the species fruited on a recently girdled, dead aspen (Populus tremula) tree (herbarium collection Miettinen 22148.1, http://id.luomus.fi/HA.H6014639).

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).