Isolation and phylogenetic identification of a dark-septate fungus associated with the alpine plant Ranunculus adoneus

Dark-septate endophytic (DSE) fungi are ubiquitous in the roots of Arctic a nd alpine plants, yet very little is known about their phylogenetic identit ies or effects on their host plants. Several such fungi were isolated from the alpine snowbed plant Ranunculus a doneus in the Front Range of Colorado, USA; one isolate was chosen for deta iled study. The ability of this isolate to re-colonize plant roots in pot c ultures was assessed, and phylogenetic analyses were performed using small- subunit (SSU), 5.8S and internal transcribed spacer (ITS) 2 ribosomal DNA s equences. This isolate had the ability to produce root endophytic structures in pot c ultures similar to those reported from other sources and observed in R. ado neus roots. SSU phylogenetic analyses showed this isolate to be related to a clade within the Euascomycetes containing the Leotiales and Erysiphales. In addition, SSU and 5.8S-ITS2 sequences showed high phylogenetic similarit y to a variety of isolates reported from other plants of diverse geographic al origins. Although most of these isolates remain unidentified, one closel y related isolate was the anamorphic taxon Phialophora gregata. The results suggest that this DSE isolate might belong to the fairly closel y related group of plant endophytes that have varied effects on the plants that they inhabit.