Arbuscular mycorrhizae on Axel Heiberg Island (80°N) and at Saskatoon (52°N) Canada

Arbuscular mycorrhizae (AM) are seldom reported from high latitudes. We found that Asteraceae (Arnica, Erigeron, and Taraxacum) at a site on Axel Heiberg Island (approximately 80 degrees N) have abundant AM and fine endophytes (FE). We used standard microscopic methods for examination and quantification, plus high-resolution confocal fluorescence imaging. AM in Arctic Asteraceae were compared with those in congeners from Saskatoon and with those in some other Arctic species. Arctic AM had 6 pm wide aseptate hyphae producing abundant arbuscules, vesicles, and inter- and intra-cellular hyphae. AM colonization exceeded 80% for Arctic Asteraceae, similar to 66%-90% for prairie Taraxacum and Erigeron, the first of this type of comparison. AM/FE abundance in Arctic Ranunculus was 68%. Within Taraxacum roots, hyphal coils predominated near the epidermis and arbuscules near the vascular cylinder. Arctic AM colonization did not vary with soil depth, although permafrost was approximately 15 cm below the surface. FE were abundant in our High Arctic samples, where they may have functional roles comparable with those of AM. Thus, low abundance of AM reported previously at the community level for high-latitude sites may reflect a combination of biotic and abiotic factors. The Axel Heiberg Island thermal oasis is ideal for functional fungal root endophyte studies in the High Arctic.