design: DNA extracted from 10 mg of leaf material using the NucleoSpin Plant II kit (Machery-Nagel, Dren, Germany) following the standard protocol. We used the forward primer fITS7 (Ihrmark et al. 2012) and reverse primer ITS4 (White et al. 1990). For DNA amplification, PCR reactions (one reaction per sample) were run in volume of 25 L and the reaction mixtures were prepared using Kapa HiFi Mastermix (Kapa Biosystems, Woburn, MA, USA).  The final library was sequenced at SciLifeLab/NGI (Solna, Sweden) on Illumina MiSeq (Illumina Inc., San Diego, CA, USA) with 2x300 bp reads.