Development of a multiplex PCR method for testing six GM soybean events

Genetically modified (GM) soybean and derived products make up a large part of the biotech-derived food and feed market. As more GM soybean varieties have been approved for commercialization, labeling requirement by South Korea and other countries needs the technical testing methods. This paper reports the development of a multiplex PCR method for identifying six commercialized GM soybean events using the event-specific fragment. Event specific primers targeting Roundup Ready Soybean (RRS, GTS40-3-2), A2704-12, DP356043-5, MON89788, A5547-127, and DP305423-1 were designed, and a multiplex PCR assay consisting of six event-specific fragments and one endogenous lectin fragment was developed. The specificity of the event-specific PCR method was confirmed using 20 GM events of maize, soybean, cotton, and canola. The limit of detection (LOD) for each event in the multiplex PCR is approximately 0.05%. Intra-lab validation by two different operators confirmed the specificity and LOD of this multiplex PCR method. The method was used to test 30 soybean-derived foods from South Korean and US markets, and results revealed three varieties of GM soybean (RRS, A2704-12, and MON89788) in 19 of the 30 food samples tested. This work provides an efficient and cost-effective approach for event-specific analysis of six commercialized GM soybean varieties and related processed foods in Korea.