Abstract: This study aimed to establish a highly specific and sensitive quantitative assay for transgenic maize CC-2, independently developed in China, using droplet digital polymerase chain reaction (ddPCR). Primers and probes were designed to target the specific insertion sequence of the CC-2 event. The reaction conditions were systematically optimized. A duplex ddPCR system was successfully developed, enabling the simultaneous detection of the endogenous gene and the CC-2 event-specific fragment. The verification results demonstrated that this method exhibited no cross-amplification in various non-target genetically modified (GM) events, confirming its high specificity; a linear response was achieved covering the range from 20 to 20 000 copies for the genomic DNA of CC-2, and the limit of detection (LOD) and limit of quantification (LOQ) were found to be 10 and 20 copies, respectively. In a blind test, the method demonstrated high repeatability and accuracy for samples containing varying concentrations of the event, meeting both national and international standards for the quantitative analysis of genetically modified organisms (GMO). The ddPCR method provides a robust technical foundation for the commercial cultivation of transgenic maize CC-2 and the regulatory monitoring of its products.

Key words: transgenic maize CC-2; droplet digital polymerase chain reaction; quantitative detection