Fungal communities associated with arcto-alpine plants are strongly shaped by regional effects

The diversity of plant-associated fungal communities in arcto-alpine pioneer plants remains elusive when compared to that of temperate climate plants. Here, we investigated the diversity of plant root associated fungal communities from two pioneer arcto-alpine plants, Oxyria digyna and Saxifraga oppositifolia, from three distinct geographic regions. DNA was extracted from bulk and rhizosphere soils and from the plant roots, after which the ITS2 region was amplified and amplicons were sequenced in order to profile the fungal communities. Diversities as well as community structures of the fungal communities were primarily impacted by the factor compartment (bulk soil, rhizosphere soil, endosphere). The highest diversities were detected in the rhizosphere soils followed by bulk soils and endosphere samples. Endosphere fungal communities exhibited community structures that were clearly distinct from those of rhizosphere or bulk soil. We detected no impact of geographic region on the diversity values of the soil fungal communities. However, remarkably, the diversities of the endosphere communities of both plant species decreased with increasing latitude. Rhizosphere and endosphere fungal community structures were influenced by geographic region, with low host plant specificity. Soil pH clearly determined the community structures of the bulk soil fungal communities. The fungal genera Mycenella, Cadophora and Varicosporium dominated the endosphere, whereas Geomyces pannorum was predominantly present in the soils.