Detection of Transgenic Components in Transgenic Soybean by Droplet Digital PCR

In order to explore the efficient technical means of identification in transgenic soybean and their derivatives, a droplet digital PCR（ddPCR） screening method was established in this study.We used soybean genomic DNA extracted by three methods to study the effects of extraction quality and preservation time on the copy number identification results of ddPCR.And we carried out the system optimization, sensitivity test and accuracy verification of the ddPCR method by applying four target elements of transgenic soybean as amplification targets. The results showed that it is more accurate and reliable to identify the foreign copy number of transgenic crops by using the DNA extracted from Promega plant genome DNA extraction kit. Compared with fluorescence quantitative screening, ddPCR was more sensitive and accurate. The optimum concentration of probe was 100 nmol·L^-1 and the optimum annealing temperature was 58 ℃. Four target elements, CaMV35 S promoter, T-NOS terminator, pat gene and T-E9 terminator, were detected by ddPCR with high sensitivity and accuracy. The absolute limit of detection（LOD） for CaMV35 S and T-NOS target parameters was two copies, five copies for pat and ten copies for T-E9 when the content of transgenic soybean was 1%. The ddPCR method established in this study can be used for quantitative detection of soybean transformants.