The ladder-shape melting temperature isothermal amplification methods for detection of CaMV 35S and CP4 EPSPS genes in soybean foods.

Abstract

Soybean has become the most widely grown genetically modified (GM) crop in the world and it is often used to produce food and feed. With the rapid development of GM technology, there is growing controversy over the safety of GM foods. It is important to develop the methods for detecting GM products rapidly and conveniently. In this paper, the LMTIA method was combined with the Proofman probes for detection of soybean, CaMV 35S soybean and CP4 EPSPS soybean. It was shown that the optimal reaction temperatures for soybean, CaMV 35S soybean and CP4 EPSPS soybean were 59, 61 and 59 °C, respectively, and the sensitivities were correspondingly 10, 100 and 100 pg/µL. The nucleic acid amplification can be completed in 20 min. For the nine non-GM soybean foods tested, neither the Proofman-LMTIA method nor the digital PCR had detected the CaMV 35S and CP4 EPSPS genes, which were consistent with the label claims. The LMTIA method was established for the rapid detection of transgenic soybeans.