Development of an Efficient Dye-Based qPCR System Still Functional for Low Levels of Transgenic DNA in Food Products

Soybean is the most common genetically modified (GM) crop globally and is mainly processed into oil. GM soybean approval and product labeling require accurate and reliable detection techniques. Current standards for real-time polymerase chain reaction (PCR) quantification of round-up ready (RR) soybean products mainly focus on probe-based methods. However, dye-based real-time PCR systems, which are low cost and have high sensitivity, may improve detection. In this study, nine quantitative primer pairs targeting the foreign fragments 35S, CTP, EPSPS, and NOS for detecting (RR) DNA were designed and evaluated to build a dye-based amplification system. Two amplification systems aimed at 35S and EPSPS in the cp4-epsps gene had good linearity (> 0.99) and high transgenic detection sensitivity (0.02%). The two systems also had a lower limit of quantification of four copies for cp4-epsps , which conforms to the ENGL recommendation. After verification, it was demonstrated that the two amplification systems had great application potential in transgenic detection of highly processed products. The qPCR system can detect soybean DNA isolated from soybean products processed in different ways with high sensitivity and specificity, making it an effective screening method.