1. Institute of Botany, University of Tartu, 40 Lai Str., EE‐51005 Tartu, Estonia;
2. These four authors contributed equally to this work
3. Systematic Botany, Göteborg University, Box 461, SE‐405 30 Göteborg, Sweden;
4. Aberdeen University, Plant and Soil Science, Cruickshank Building, St Machar Drive, Aberdeen, AB24 3UU, UK;
5. Swedish University of Agricultural Sciences, Forest Mycology and Pathology, Box 7026, SE‐750 07 Uppsala, Sweden;
6. Lund University, Microbial Ecology, Ecology Building, SE‐223 62 Lund, Sweden;
7. University of Oslo, Division of Botany and Plant Physiology, Department of Biology, PO Box 1045 Blindern, N‐0316 Oslo, Norway;
8. University of Copenhagen, Botanical Institute, Department of Mycology, Oster Farimagsgade 2D, DK‐1353 Copenhagen K, Denmark;
9. METLA, Finnish Forest Research Institute, Vantaa Research Centre, Box 18, FIN‐01301 Vantaa, Finland;
10. The Macaulay Institute, Environmental Sciences Group, Craigiebuckler, Aberdeen, AB15 8QH, UK;
11. Karolinska Institutet, Center for Genomics and Bioinformatics, Berzelius v. 35, SE‐171 77 Stockholm, Sweden;