Endorhizal Fungi Associated with Vascular Plants on Truelove Lowland, Devon Island, Nunavut, Canadian High Arctic

Abstract

Truelove Lowland on Devon Island, Nunavut (75°N), has long been investigated for its flora, fauna, and microbiota. Unlike ectomycorrhizae, endomycorrhizal interactions have been described as sparse or absent in this High Arctic environment. To probe this observation, samples of roots and associated soils (55 plants in total) from 10 genera in 9 families were collected during July 2006. Fungi growing within these roots were visualized using our high-sensitivity lactofuchsin epifluorescence method. Fungal colonization within plant roots (collectively, endorhizal fungi) was assessed with our quantitative microintersect method. Of the 3988 intersections assessed at 400× total magnification, only 154 lacked fungi. Most colonization was by septate endophytes (average abundance 66%, range 13–100%), and fine endophytes (average abundance 48%, range 0–100%). Endorhizal morphology in Dryas and Saxifraga roots typically consisted of thin extraradical hyphae that formed a sheath and grew between and within root cortical cells, resembling ericoid or ectendomycorrhizae. Soil in which the Truelove plants had grown, which had been stored at −20 °C, was planted with wheat seeds. After 10 weeks, fungal colonization of these roots was 35–100%. Endorhizal fungi are typically present in roots of plants living on Devon Island tundra.