Metabarcoding Reveals Diverse Endophytic Fungal Communities in Vaccinium Myrtillus Plant Organs and Suggests Systemic Distribution of Some Ericoid Mycorrhizal and DSE Fungi

Genome sequencing data revealed unexpected similarities among plant-interacting fungi belonging to different ecological guilds. In particular, the sequenced genomes of ericoid mycorrhizal fungi (ErMF) showed closer similarities with genomes of plant endophytes than with those of other mycorrhizal fungi. ErMF are typically associated with roots of plants in the Ericaceae, but it has never been investigated whether they also colonize other organs of their natural hosts. Here, we applied a metabarcoding approach to describe the fungal community associated with the different organs of Vaccinium myrtillus plants collected in the field. Taxa in the Helotiales and Sebacinales, known to include ErMF, characterize the root endosphere, together with Agaricales and Lecanoromycetes, while the stems were enriched in Agaricomycetes, Tremellomycetes and Pleosporales, the leaves were enriched in Sordariomycetes, Hysteriales, and the flowers were enriched in Dothideomycetes. Operational Taxonomic Units attributed to known or putative ErMF and Dark Septate Endophytic fungi, namely Pezoloma ericae, Meliniomyces spp. and Phialocephala fortinii, were found in all the plant organs. The ErMF Oidiodendron sp. was rarely detected in organs other than roots in field samples, but we could detect its presence in the above-ground organs of V. myrtillus grown in vitro. This first report of ErMF colonizing the above-ground tissues of the host plant mirrors their evolutionary closeness with endophytes and increases the list of fungi found to occupy several niches.