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Title: Transgene movement in commercial alfalfa seed production: Implications for seed purity

Author
item KESOJU, SANDYA - Washington State University
item Greene, Stephanie
item Martin, Ruth
item Kramer, Matthew

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/28/2015
Publication Date: 11/16/2015
Citation: Kesoju, S.R., Greene, S.L., Martin, R.C., Kramer, M.H. 2015. Transgene movement in commercial alfalfa seed production: Implications for seed purity. Meeting Abstract. Crop Science Society of America, Minneapolis, MN, Nov 15-18, 2015.

Interpretive Summary: The United States is a major exporter of alfalfa seed and hay and the organic dairy industry is one of the fastest growing agricultural sectors. With the advent of genetically-engineered (GE) alfalfa concerns have risen regarding the coexistence of GE and non GE alfalfa since the crop is largely out-crossing and is insect-pollinated. Our objective was to better understand how pollinators moved GE pollen on a landscape scale. In spring (2013), alfalfa seed and hay fields were mapped in the Touchet Valley, Walla Walla County, WA. GE seed fields (source fields) and 14 conventional seed fields (sink fields), located at various distances from GE sources, were identified. Distance from pollinator domiciles, pollination species, field size and environmental characteristics such as elevation, aspect, slope, and distance to riparian areas and open range land were also obtained. We found that GE and non GE fields needed to be separated by 330 m, 602 m and 2441 m, to ensure AP levels were less than 0.9%, 0.5% and 0.1% AP respectively, with 95% confidence. We found that other variables influenced the movement of GE traits by bees. The take home message was that from the perspective of seed producers, distance remains the simplest variable to account for.

Technical Abstract: The United States is a major exporter of alfalfa seed and hay and the organic dairy industry is one of the fastest growing agricultural sectors. With the advent of genetically-engineered (GE) alfalfa concerns have risen regarding the coexistence of GE and non GE alfalfa since the crop is largely out-crossing and is insect-pollinated. Our objective was to quantify the extent of transgene movement from GE seed fields to conventional seed fields on a landscape levelto define GE pollen dispersion curves based on the spatial distribution of commercial seed fields. In spring (2013), alfalfa seed and hay fields were mapped in the Touchet Valley, Walla Walla County, WA. GE seed fields (source fields) and 14 conventional seed fields (sink fields), located at various distances from GE sources, were identified. Distance from pollinator domiciles, pollination species, field size and environmental characteristics such as elevation, aspect, slope, and distance to riparian areas and open range land were also obtained. We found that GE and non GE fields needed to be separated by 330 m, 602 m and 2441 m, to ensure AP levels were less than 0.9%, 0.5% and 0.1% AP respectively, with 95% confidence. We found that adding explanatory variables to our model could reduce isolation distances. Establishing isolation distances to ensure coexistence of GE and non GE alfalfa seed production is a challenging task since gene flow is influenced by pollinator behavior, distance, and field size. The results of this landscape scale study illustrate conservative isolation distances needed to ensure various AP thresholds in Walla Walla County, WA. Although other variables can be taken into account to refine isolation distances, from the perspective of seed producers, distance is the simplest variable to account for.