Improvement of the group testing method to evaluate GM maize content
2016
Mano, J. (National Food Research Institute, NARO, Tsukuba (Japan)) | Takashima, K. | Futo, S. | Minegishi, Y. | Ninomiya, K. | Noguchi, A. | Kondo, K. | Teshima, R. | Takabatake, R. | Kitta, K.
The use of genetically modified (GM) stacked-event products combining two or more GM parental events, especially in maize, has been increasing. This situation has made real-time PCR-based quantitative methods prone to overestimation of the content of GM organisms (GMOs) relative to the actual weight proportion. To solve this problem, we previously proposed a group testing method enabling accurate weight-based evaluation of GMO content in maize grains. In the present study, this method was slightly modified and validated in-house in order to enhance its reliability and user friendliness. Additionally, we developed a testing method for identification of GM events in the lysate samples used for the group testing. First, we confirmed specificity of the modified method by means of authentic GM and non-GM materials. Evaluation of the limit of detection suggested that the modified method reliably detected a single GM kernel in a group sample composed of 20 maize kernels. Then, we conducted a blind test using simulated group samples. All of the testing results matched the presence/ absence of GM kernels in the simulated samples. Furthermore, identification of GM events in the group testing samples was successfully achieved by DNA purification from the residual lysates and subsequent real-time PCR array analyses.
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