Screening method for detection of genetically modified soybean and maize events using multiplex PCR combined with capillary electrophoresis

Positive controls are essential for detecting genetically modified (GM) crops; however, their acquisition and usage in analysis are limited. Moreover, event-specific markers make it difficult to screen numerous samples efficiently. In this study, we developed an introduced gene-based screening method for GM crops using standard plasmids as positive controls, combined with multiplex PCR (mPCR) and capillary electrophoresis (CE). Eighteen introduced gene sequences, four promoters (P-ubi10, P-act1, P-rbcS, and P-TSF1), six terminators (T-35S, T-pinII, T-E9, T-tml, T-hsp17.3, and T-H4), and eight target genes (pat, bar, CP4epsps, mEPSPS, aad1, gat4621, csr1-2, and DMO) were combined to construct standard plasmids for soybean and maize GM events. Three mPCR sets, 3–4 primer pairs each, were designed to simultaneously detect multiple introduced genes and distinguish GM samples from non-GM samples and crop events. Furthermore, CE demonstrated high resolution and sensitivity, resolving amplicons with minimal size differences and accurately detecting them at low concentrations. Overall, the approach used in this study provides a cost-effective and feasible screening platform for border inspection and monitoring of GM crops.