Figure 2.

1-step and 2-step PCR amplification approach. In the 1-step PCR (right), the target gene is amplified using primers sequence composed of forward and reverse target gene primer, overhang linkers, barcodes, and Illumina adapters to bind to a flow cell in Illumina sequencing. In the 2-step PCR amplification (left), the primer of the first-step PCR contains a specific forward and reverse primer and an overhang adapter. For the second-step PCR, the primers have an overhang linker, barcodes, and the Illumina flow-cell linker sequence.