Abstract: A rapid method for detection of genetically modified maize by multiplex polymerase chain reaction(PCR) followed by capillary electrophoresis with laser-induced fluorescence was developed. The triplex PCR procedure was applied to simultaneously amplify CaMV 35S promoter and the junction between hsp70 intron 1 and CryIA(b) gene as well as Invertase gene. The amplified products were analyzed by capillary sieving electrophoresis with laser-induced fluorescence detection. The parameters of multiplex PCR and capillary sieving electrophoresis were optimized. Under the optimal conditions, the proposed method was able to simultaneously detect the three heterogenous genes existing in genetically modified maize. The amplified DNA fragments were sequenced and showed the good agreement with original gene, which indicated the reliability of the amplification reaction. The limit of detection was 0.05%, which is much lower than 1% threshold for labeling genetically modified food required by the European Community. There was a good agreement in the determined results of maize and its products by using this method and real-time quantitative PCR method. Compared with conventional agarose gel electrophoresis, the proposed method offered a more specific and sensitive procedure to rapid screening, identification and detection of genetically modified maize.

Key words: Multiplex polymerase chain reaction, Capillary sieving electrophoresis, Laser-induced fluorescence detection, Genetically modified maize