A targeting method is described that allows precise cassette replacement at a previously characterized genetic locus. A target DNA construct containing a pair of incompatible FRT sites flanking a target cassette was introduced into soybean by regular biolistic transformation. Transgenic events containing a single complete copy of the target site were then selected and retransformed with a donor DNA construct containing the identical pair of incompatible FRT sites flanking a donor cassette. Precise DNA cassette exchange happened between the target cassette and the donor cassette via recombinase mediated cassette exchange (RMCE) so that the donor cassette was introduced at the exact genomic site previously occupied by the target cassette. Through repeated RMCE using additional incompatible FRT sites, multiple groups of transgenes can be stacked at the same genomic locus.
