Detection of sixteen genetically modified maize events in processed foods using four event-specific pentaplex PCR systems

To efficiently identify genetically modified (GM) maize events in foods and feeds, we report here the development of four individual pentaplex PCR analysis systems for event-specific identification of sixteen GM maize events approved in South Korea. In addition to the maize endogenous reference gene, zSSIIb, the four pentaplex PCR assays target group 1 containing TC6275, MON810, T25, and NK603; group 2 with TC1507, MON863, GA21, and DAS-59122-7; group 3 with MIR604, Bt11, Bt176, and MON89034; group 4 with event 3272, LY038, MIR162, and MON88017. These amplicons were designed to be smaller than 200bp to make the testing system suitable for analyzing processed foods/feeds derived from these 16GM maize events. After optimizing the reaction condition, the limits of detection of these four assays were approximately 0.25% for all of the 16GM maize events. This multiplex PCR method for sixteen GM maize events was validated by three operators, and the data confirmed the reliability of the developed assays. Furthermore, 74 food samples containing maize ingredients from the USA, China, Japan, and South Korea were analyzed, and we observed 18 food products containing one or more GM maize events. These results suggest that the developed multiplex system is applicable for use in specific testing of sixteen GM maize events in foods and feeds in South Korean market.