Soil selenium shapes microbial fungal structure in culti-vated soils
To assess differences in microbial community composition among samples, a Fast DNA Spin Kit for Soil (MP Biomedicals) was used to extract genomic DNA from the soil samples. Primers 27F (5'-AGAGTTTGATCMTGGCTCAG-3') and 1492R (5'-GGTTACCTTGTTACGACTT-3') were used to amplify the bacterial 16S rRNA gene, while primers ITS1F (5'-TCCGTAGGTGA ACCTGCGG-3') and ITS4R (5'-TCCTCCGCTTATTGATATGC-3') were used to amplify the fungal ITS gene. The PCR amplification system was configured as follows: 4 L of 5 Buffer, 2 L of 2.5 mmol/L dNTP Mixture, 0.8 L of Forward primer, 0.8 L of Reverse primer, 0.4 L of Polymerase, 10 ng of Template DNA, and ddH2O, with the total volume adjusted to 20 L. The thermal cycling program was set as follows: initial denaturation at 95 C for 5 min to initiate the reaction; followed by 35 cycles, each consisting of denaturation at 95 C for 30 s, annealing at 58 C for 30 s, and extension at 72 C for 45 s; after the cycles, a final extension at 72 C for 10 min was performed to fully extend the products. The final reaction system was stored at 6 C for subsequent use. The amplified products were subjected to high-throughput sequencing on the Illumina MiSeq platform (Shanghai Lingen Biotechnology Co., Ltd.). The resulting sequence data were used to analyze microbial community composition and diversity following quality control, filtering, and merging overlapping sequences.