High diversity of root associated fungi in both alpine and arctic Dryas octopetala

Abstract

BackgroundDryas octopetala is a widespread dwarf shrub in alpine and arctic regions that forms ectomycorrhizal (ECM) symbiotic relationships with fungi. In this study we investigated the fungal communities associated with roots of D. octopetala in alpine sites in Norway and in the High Arctic on Svalbard, where we aimed to reveal whether the fungal diversity and species composition varied across the Alpine and Arctic regions. The internal transcribed spacer (ITS) region of nuclear ribosomal DNA was used to identify the fungal communities from bulk root samples obtained from 24 plants.ResultsA total of 137 operational taxonomic units (OTUs) were detected (using 97% similarity cut off during sequence clustering) and well-known ECM genera such as Cenococcum, Cortinarius, Hebeloma, Inocybe and Tomentella occurred frequently. There was no decrease in fungal diversity with increasing latitude. The overall spatial heterogeneity was high, but a weak geographical structuring of the composition of OTUs in the root systems was observed. Calculated species accumulation curves did not level off.ConclusionsThis study indicates that the diversity of fungi associated with D. octopetala does not decrease in high latitude arctic regions, which contrasts observations made in a wide spectrum of other organism groups. A high degree of patchiness was observed across root systems, but the fungal communities were nevertheless weakly spatially structured. Non-asymptotical species accumulation curves and the occurrence of a high number of singletons indicated that only a small fraction of the fungal diversity was detected.

Living strategy of cold-adapted fungi with the reference to several representative species

“…Coupled with previous sporocarp collections (Gardes and Dahlberg 1996), the frequently occurred fungal genera that either lack or produce sporocarps are Thelephora, Sebacina and Clavulina . EMF resulted from analysis of root tips and soil clones in Arctic revealed their extremely high richness (Bjorbaekmo et al 2010; Geml et al 2012), comparing with previous estimation based on surveys of above-ground ECM sporocarps. A large number of OTUs were detected in Arctic, with 137 OUTs on the roots of Dryas octopetala along a latitudinal gradient from Southern Norway to Svalbard (Bjorbaekmo et al 2010), 73 ECM basidiomycete OTUs in soils on Svalbard (Geml et al 2012) and 224 OTUs in the roots of three co-occurring species in the Low Arctic (Walker et al 2011).…”

“…It is estimated that 86% of the N obtained by Arctic plants is via mycorrhizal, notably ectomycorrhizal (ECM) fungi (Hobbie and Hobbie 2006). EMF genera were the most frequent and species-rich associated with plants in the Arctic (Bjorbaekmo et al 2010; Deslippe et al 2011; Geml et al 2012). Coupled with previous sporocarp collections (Gardes and Dahlberg 1996), the frequently occurred fungal genera that either lack or produce sporocarps are Thelephora, Sebacina and Clavulina .…”

Enigmatic Sebacinales

“…They recorded Sebacinales as essential components in this highly specialized ecosystem. Within 137 OTUs sequenced from D. octopetala, 6,9 % belonged to Sebacinales (Bjorbaekmo et al 2010). Garnica et al (2012) also recorded Sebacina mycobionts on D. octopetala ECMs in the Alps.…”

The genus Hebeloma in the alpine belt of the Carpathians including two new species

“…In addition to these traditional studies European Arctic-alpine fungal communities have been studied by high throughput sequencing (e.g. Bjorbaekmo et al 2010, Fujiyoshi et al 2011, Lentendu et al 2011, Geml et al 2012, Botnen et al 2014. Also the Arctic region of Greenland has been relatively well studied mycologically (Borgen et al 2006).…”