Detection and characterization of recombinant DNA in the Roundup Ready® soybean insert

The genetically modified (GM) Roundup Ready® soybean event GTS 40-3-2 contains the bacterial gene 5-enol-pyruvylshikimate-3-phosphate synthase. A 534 bp rearrangement of the DNA in the 3′ region flanking the functional insert likely occurred as a consequence of the insertion event. The structure of the DNA surrounding the insertion has not been fully characterized. A semi-nested PCR method identified the rearranged soybean DNA in samples of raw, partially processed and highly processed food at a level of 0.01%. The 534 bp rearranged segment contained a contiguous portion at least 238 bp long that was also identified in non-GM soybeans. Specific combinations of semi-nested PCR primers differentiated GM and non-GM soybean DNA. These studies confirm that the rearranged DNA originates from the soybean genome and does not involve the introduction of non-soybean genetic material.