The construction of pMD18-HT-Soybean as a calibrator plasmid and nested PCR assay for herbicide-tolerant soybeans

A multiple-target plasmid designated as pMD18-HT-Soybean, comprising part of a junction region of genetically modified soybean events A2704-12, A5547-127, MON89788 and GTS-40-3-2, and the endogenous soybean-specific lectin gene were constructed. The limit of detection for quantification of these four event-specific genes using pMD18-HT-Soybean plasmid was 20 copies. Furthermore, a nested PCR detection method was developed for the above four genetically modified soybean events. LOD value of nested PCR detection was 0.005 %. The above results demonstrated that the plasmid pMD18-HT-Soybean DNA represents a valuable alternative to genomic DNA as a calibrator for the quantification of soybean event GTS-40-3-2, MON89788, A2704-12 and A5547-127 in food and feed products. And the validated results also indicated that the developed nested PCR method can be used for identification and quantification of four genetically modified soybean events and its derivates.