Using equivalent DNA mix of six different GM events including Bt11 of maize, MON 15985 of cotton, GM rice with bar gene, Huanong No. 1 of papaya, RRS of soybean and GM canola with hpt gene. Lanes 1∼15, PCR runs starting with the largest amplicon (by hpt gene-specific primer, amplicon size 879 bp), followed by the addition of a second primer pair, until the fifteenth primer pair; lanes1′∼15′, PCR runs starting with the fifteen-plex amplicon, followed by the elimination of the largest amplicon primer pair (by hpt gene-specific primer, amplicon size 879 bp), until only the smallest amplicon (by FatA gene-specific primer, amplicon size 116 bp) remained; lane M, 100 bp DNA Marker.