Herbicide resistant wheat (Triticum aestivum)could be used as part of a management strategy for jointed goatgrass (Aegilops cylindrica). The presence of a shared genome (DD) between the two polyploid species allows for the production of natural hybrids. Placement of a herbicide resistance gene in wheat on the unshared genomes (AA, BB) may be a way to reduce the risk of gene migration from wheat to jointed goatgrass. To determine the effect of transgene genome location on gene movement, crosses were made between jointed goatgrass and wheat lines that carry the CP4-EPSPS gene for glyphosate resistance on either, the A, B or D genome. Prior to the initial backcross with jointed goatgrass, the F₁ hybrids were sprayed with glyphosate to confirm herbicide resistance. The BC₁ population was divided into two sub-populations: Sprayed and non-sprayed with glyphosate. Both populations were similar for germination rate, chromosome number, and gene transmission rate. In contrast, the BC₂ generation that resulted from the sprayed sub-population differed from non-sprayed population with respect to germination rate and gene transmission rate. A lower germination rate but higher gene transmission rate in the sprayed population compared to non-sprayed population was observed. We propose that the high gene transmission in sprayed BC₂ progeny is occurring due to gametophytic and/or sporophytic selection due to residual glyphosate. Experiments to test this hypothesis will be discussed.