Assessment of the Real-Time PCR Method Claiming to be Specific for Detection and Quantification of the First Commercialised Genome-Edited Plant

Abstract

A real-time PCR method was recently published with a claim to be specific for the detection and identification of some genome-edited oilseed rape (OSR) lines commercialised in North America. The method was designed to detect a single base mutation in the AHAS1C gene, which confers herbicide tolerance. The authors claim that the method is event-specific for the genome-edited OSR line 5715 and fulfils all requirements for GMO analytical methods according to EU regulations. We have thoroughly assessed the method in relation to the minimum performance requirements (MPR) established by the European Network of GMO Laboratories (ENGL). The method was found to be sufficiently sensitive and robust when tested with pure genomic DNA of the OSR line 40 K. However, our results show that the method is not event-specific and detects also OSR lines carrying the same point mutation caused by somaclonal variation. Moreover, impaired robustness was observed using non-modified genomic DNA at the amount specified in the original protocol. Significant non-specific PCR amplifications with PCR products as non-target template DNA and with genomic DNA from numerous OSR varieties as well as from wild radish were found by three ISO/IEC 17025 accredited reference laboratories in tests using different master mixes and PCR cycler models. The assessment shows that the method does not meet the MPR for qualitative PCR methods and therefore is not fit-for-purpose for official controls of genetically modified products in the EU. Suggestions are provided for conditions under which analytical methods for genome-edited organisms should be validated.