UC Riverside

Studying transgene flow will enhance our understanding of the fate of crop alleles in nearby populations. In addition to the potential for weediness, gene flow from transgenic crops into neighboring fields could have severe economic consequences if those fields are destined for markets with strict thresholds for transgene detection. This study can serve as a model system for understanding transgene introgression in free-living populations.Transgene escape has been documented for at least eight different species. I chose to work with Alfalfa (Medicago sativa) due to its proximity and because there was already previous data from a 2011 survey to allow for a greater time span analysis of results. Almost half of the populations at each of the three sites surveyed were still remaining in 2019, indicating that feral alfalfa populations are self-perpetuating. About half of the populations surveyed at each site were still remaining from 2019 to 2021. The presence of the transgene increased at all three sites from 2011 to 2019, likely due to unilateral gene flow from nearby transgenic alfalfa production. It is of concern that feral populations may act as bridges to facilitate transgene movement, so the increase in transgene presence is not desirable. Mowing, tilling, and spraying are sometimes used to manage feral roadside populations. Tilling was the most efficient method to eradicate feral alfalfa populations. No differences in effectiveness were observed between other management types. This is the longest timespan data has been collected for transgene flow into feral populations. Having data that spans across a decade will enable a more complete understanding of the dynamics between population presence, transgene presence, management type, and other site characteristics.