16S rDNA sequences of soil samples :AWT soil sample with R years continuous cropping of cotton
Soil microbial DNA extraction was obtained and purified. V4 hypervariable region of bacterial 16S rDNA was amplified. The reverse primer combined with a barcode sequence. PCR amplification was used in a 25 μl reaction, containing 1 μl of each primer, 2.5 μl AccuPrime PCR buffer II (Invitrogen, Grand Island, NY, USA), 5 μl DNA and 0.1 μl AccPrime Taq Polymerase. The reaction mixture was denatured at 94 oC for 1 min, followed by 30 cycles of 94 oC for 20 s, 53 oC for 25 s and 68 oC for 45s, and extension at 68 oC for 10 min. The PCR products were purified and run using a Miseq (Illumina, San Diego, CA, USA).