Development of a screening method for the monitoring of 38 genetically modified maize events in food and feed in South Korea

A multiplex PCR system was developed to trace GM maize events in food and feed. Genetic elements of 38 single GM maize events were investigated, and 10 screening targets were selected as follows: promoters [Cauliflower mosaic virus (CaMV) 35S, rice actin 1 gene (rAct1)], terminators [CaMV 35S, Agrobacterium nopaline synthase (nos), proteinase inhibitor II of potato (PinII), heat shock protein 17 of wheat (hsp17)] and structural genes [cry1A gene derived from Bacillus thuringiensis, phosphinothricin acetyltransferase gene derived from Streptomyces hygroscopicus (bar), and Streptomyces Viridochromogenes (pat), 5-enolpyruvulshikimate-3-phosphate synthase enzyme derived from Agrobacterium tumefaciens strain CP4 (cp4-epsps)]. These screening targets were combined in three individual multiplex PCR assays. The method specificity was confirmed by detecting the specific amplification of DNA derived from 16 different GM maize events. The limit of detection of the multiplex PCR system was tested using the certified reference materials of GM maize events with different GM % (w/w) and approximately 0.1%. To test the applicability of the developed screening method, 22 food samples containing maize as ingredients, and 36 maize kernels were analyzed. Various types of single and/or stacked GM events were found in 11 food and 20 maize kernel samples. These results demonstrate that the screening method developed may be useful for tracking GM maize events in food and feed.