## 2 Materials and Methods
### High-Throughput DNA Sequencing  
The genomic DNA of total 48 soil samples was extracted using an EZNA Soil DNA extraction kit (Omega, Norcross, GA, USA) according to the manufacturer's instructions (0.5 g per sample). The V3-V4 and ITS3-ITS4 amplicons of 16S rRNA genes and an internal transcribed spacer between ribosomal genes were amplified using a KAPA HiFi Hot Start Ready Mix (2x, TaKaRa Bio Inc., Kusatsu City, Japan). Universal PCR primers (PAGE purified) were used including the bacterial PCR forward primer (CCTACGGGNG-GCWGCAG) and reverse primer (GACTACHVGGGATCTAATCC) in addition to the fungal forward primer (GCATCGATGAAGAACGCAGC) and fungal reverse primer (CTCCGCGCTTATTGATATGC) [35; 36] (primer sequences provided by Sangon Biotech company(Shanghai, China)). Reactions included 2 uL of DNA (10 ng \(\mu\)L\({}^{-1}\)); 1 uL each of PCRforward and reserve primers (10 \(\upmu\)mol each); 15 \(\upmu\)L of 2\(\times\) KAPA HiFi Hot Start Ready Mix; and total reaction 30 \(\upmu\)L. PCR plates were sealed and PCRs were performed in a thermal cycler (Applied Biosystems 9700, Waltham, MA, USA) using the following steps: pre-denaturation at 94 \({}^{\circ}\)C for 3 min, followed by denaturation at 95 \({}^{\circ}\)C for 20 s, 20 s of annealing at 55 \({}^{\circ}\)C, and a final extension at 72 \({}^{\circ}\)C for 30 s. The above denaturation, annealing, and extension steps were repeated for 20 cycles. The PCR products were detected gel electrophoresis using a 1% agarose gel in TBE (Tris-H\({}^{3}\)BO\({}^{3}\)-EDTA) buffer and stain with ethidium bromide (EB), followed by visualization with UV light. Samples were used to construct libraries using the universal Illumina adapters and indices. Sequencing was then performed on an Illumina MiSeq system (Illumina MiSeq, San Diego, CA, USA). The paired-end (PE) reads were obtained via paired-end sequencing and first combined using the fast length adjustment of short reads (FLASH) software package, which was also used to quality filter the datasets and obtain high-quality sequences for subsequent analysis. Using PRINSEQ to cut off the bases with quality value below 20 in the tail of reads, and set a 10 bp window. If the average quality value in the window is lower than 20, cut off the back-end bases from the window, filter the N-containing sequences and short sequences after quality control and finally filtered out the sequences with low complexity. After sequencing, chimeras were removed using the UCHIME programs. Quality-filtered sequences from each sample were taxonomically classified using the RDP classifier accessed on 28 June 2020. (RDP 16S database: [[http://rdp.cme.msu.edu/misc/resources.jsp](http://rdp.cme.msu.edu/misc/resources.jsp)]([http://rdp.cme.msu.edu/misc/resources.jsp](http://rdp.cme.msu.edu/misc/resources.jsp)) and RDP ITS database: [[http://rdp.cme.msu.edu/misc/resources.jsp](http://rdp.cme.msu.edu/misc/resources.jsp)]([http://rdp.cme.msu.edu/misc/resources.jsp](http://rdp.cme.msu.edu/misc/resources.jsp))). A total of 211,930 bacterial sequences with 211,696 valid sequences and 67,106 fungal sequences with 66,988 valid sequences were detected. The datasets generated during the current study have been uploaded to the Sequence Read Archive (SRA), and had the accession number PRJNA763299.