Efficient retrieval of recombinant sequences of GM plants by Cauliflower Mosaic Virus 35S promoter-based bidirectional LT-RADE

摘要

Identification of genetically modified (GM) plants remains a difficult task, especially when few information on the GM content in a sample is available. The P-35S is a commonly applied genetic element in GM plants and represents as such a suitable starting point for the tracing of GM plants. Here, the application of a CaMV P-35S LT-RADE genome walking method on five different genetically modified (GM) crops is documented: MON810 maize, LLRICE62 rice, T45 rapeseed, A2704-12 soybean and LLCOTTON25 cotton. Two sets of oligonucleotide primers are presented as a potential forward or reverse genome walking strategy with genomic DNA as template. The method’s robustness and suitability for assessing the recombinant nature of P-35S positive signals is presented in detail. This study demonstrates for the first time the general applicability of LT-RADE in molecular characterization of GMOs retrieving several previously unknown transgenic insert nucleotide sequences. Current limitations and future developments are discussed.