18s-seq of AMF
The soil DNA was extracted from 0.25 g frozen soil samples using a PowerSoil DNA Isolation Kit (MoBio Laboratories, Inc., Carlsbad, CA, USA). An approximately 334 bp region of the 18S rDNA gene was amplified with two-step PCR. Briefly, the extracted DNA was diluted 10 times and amplified with GeoA-2 (Schwarzott and Schler, 2001) / AML2 (Lee et al., 2008) in the first amplification. The PCR product was then diluted 10 times and amplified with NS31 (Simon et al., 1992) / AMDGR (Lumini et al., 2010) in the second amplification. The primer NS31 was modified with a unique 12 nt barcode at the 5end. The PCR systems and conditions were described by Yang et al. (2019). The purified PCR products from all samples were mixed sequenced at the Environmental Genome Platform of Chengdu Institute of Biology, Chinese Academy of Sciences.