GH ITS2
The plant ITS2 region was amplified using the primers ITS-S2F ATGCGATACTTGGTGTGAAT andITS-p4 CCGCTTAKTGATATGCTTAAA (Cheng et al, 2016). An additional 5 bases of inline barcode wereincorporated at the 5 end of the primers to enable inline barcoding (Glenn et al. 2019). Different sampleswere amplified using different combinations of the forward and reverse inline primers. PCR was performedusing SolarBio PCR mastermix (SolarBio, China) with the PCR profile of : 95C for 3 minutes followed by 40cycles of 95C for 15 s, 47C for 20s and 72C for 15s.The barcoded amplicons were subsequently visualized on gel and purified using 0.8 X of SPRI bead. Thepurified amplicons were used as the template for 8 cycles of index PCR to incorporate the complete Illuminaadapter and Illumina-compatible dual-index barcodes.The constructed libraries were subsequently size-selected using 0.8 X vol of SPRI bead and pooled into asingle tube. Quantification of the pooled libraries used Denovix high sensitivity assay. Sequencing of thepooled libraries was performed on a NovaSEQ6000 (Illumina, San Diego) using the 2 x 150 bp paired-endsequencing configuration.