Event-specific PCR methods to quantify the genetically modified DBN9936 maize

The genetically modified (GM) maize DBN9936 that has been granted a biosafety certificate needs to be regulated in China. An event-specific PCR assay targeting the junction region between the left border of its T-DNA and the flanking genomic DNA (gDNA) was established to be able to specifically identify the DBN9936 event from other GM maize and non-GM maize. Both qPCR and duplex ddPCR achieved accurate measurement of DBN9936 content in blind matrix and gDNA samples with acceptable precision in terms of a relative standard deviation (RSD) of <25 % and a trueness in terms of relative bias of ±25 %. The quantitative values of the same sample did not show significant difference between qPCR and duplex ddPCR, whereas the duplex ddPCR showed advantage over qPCR in terms of precision. This study provided an event-specific PCR method for identification and quantification of DBN9936 on both a real-time PCR platform and a ddPCR platform.