Development of an event-specific detection method for genetically modified rice Kefeng 6 by quantitative real-time PCR

The genetically modified (GM) rice Kefeng 6 has gained resistance against several rice pests by inserting the cpti and cry1Ac genes. As this transgenic line is not approved for import, processing and cultivation in the European Union (EU), sensitive and specific detection methods need to be available to monitor any illegal presence of Kefeng 6 in food products within the EU. The aim of this study was to develop and validate an event-specific detection method by means of quantitative real-time PCR (qPCR) for the detection of Kefeng 6 in foodstuff. A primer pair and hydrolysis probe were designed according to the right border junction sequence of the transgene. The qPCR assay was validated according to the ENGL/EURL-GMFF guidelines for GMO testing and is presented according to the MIQE guidelines. The in-house validation process resulted in a limit of detection of 5 DNA copies of the transgene with confidence intervals (95 %) between 0.07 and 0.52, a PCR efficiency of 105 % and a correlation coefficient (R (2)) value of 0.9997. The specificity of the assay was tested by end-point PCR, gel electrophoresis and subsequent sequencing of the PCR products. By testing DNA of several GM and non-GM crops, cross reactivity of the assay was not observed. Further, 35 food products were analyzed for the presence of Kefeng 6 by means of the event-specific detection method. For 9 out of 35 samples, PCR products for Kefeng 6 DNA were observed.