A multiplex PCR method of detecting recombinant DNAs from five lines of genetically modified maize

Seven lines of genetically modified (GM) maize have been authorized in Japa n as foods and feeds imported from the USA. We improved a multiplex PCR met hod described in the previous report in order to distinguish the five lines of GM maize. Genomic DNA was extracted from GM maize with a silica spin co lumn kit, which could reduce experimental time and improve safety in the la boratory and potentially in the environment. We sequenced recombinant DNA ( r-DNA) introduced into GM maize, and re-designed new primer pairs to increa se the specificity of PCR to distinguish five lines of GM maize by multiple x PCR. A primer pair for the maize intrinsic zein gene (Ze1) was also desig ned to confirm the presence of amplifiable maize DNA. The lengths of PCR pr oducts using these six primer pairs were different. The Ze1 and the r-DNAs from the five lines of GM maize were qualitatively detected in one tube. Th e specific PCR bands were distinguishable from each other on the basis of t he expected length. The r-DNA could be detected from maize samples containi ng 0.5% of each of the five lines of GM maize. The sensitivity would be acc eptable to secure the verification of non-GMO materials and to monitor the reliability of the labeling system.