Contribution of environmental DNA toward fungal Red Listing

In navigating the biodiversity crisis, a major uncertainty is the conservation status of inconspicuous, yet megadiverse and functionally crucial, soil organisms. Massive datasets on soil biota are accumulating through molecular sampling approaches, but to date these datasets have provided only limited input into conservation planning and management. We investigated how environmental DNA (eDNA) data of soil macrofungi contribute to regional Red List assessments, which are currently based on fruiting bodies (hereafter, fruit-bodies). In our test region of Estonia (northern Europe), which contained ~15,000 fruit-body records for 1583 assessed species, an average soil sample increased the range estimates of Threatened and Near Threatened fungal species by 0.18%. Five hundred soil samples almost doubled their known localities and added 19% previously unrecorded species. However, even after accumulating >1000 soil samples, about half of the Threatened and Near Threatened species known by fruit-bodies remained undetected through eDNA techniques. Effective conservation assessment of soil fungi thus requires both fruit-body and eDNA data; therefore, special efforts are needed to make these data available to conservationists.