Development of an event-specific PCR method to quantify genetically modified soybean DBN8002 on both real-time and digital PCR platforms

The genetically modified (GM) soybean DBN8002 has been approved for commercial planting in China. For enforcing GMO labeling policy, an event-specific real-time quantitative PCR (qPCR) method was developed to target the junction fragment between the T-DNA left border and the flanking genomic DNA, yielding a 104 base pair (bp) amplicon. This event-specific qPCR method can identify and quantify the DBN8002 event with high specificity, satisfactory linearity, and acceptable accuracy. Furthermore, the DBN8002-event specific primer/probe set was successfully transferred to a droplet digital PCR (ddPCR) platform for quantification. The quantitative results from qPCR were found to be comparable to those obtained from ddPCR, with a P-value exceeding 0.05, indicating no significant difference. The limit of detection (LOD) for both qPCR and ddPCR methods was determined to be 10 copies per reaction, while the limit of quantification (LOQ) was estimated to be 20 copies per reaction for qPCR and 40 copies per reaction for ddPCR. The collaborative validation demonstrated that the DBN8002 event-specific qPCR method had satisfactory repeatability and reproducibility. Both the event-specific qPCR and ddPCR methods are suitable for quantifying the DBN8002 content in samples. Additionally, ddPCR can be utilized for the characterization of DBN8002 reference materials.