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Title: Update on RR gene flow research

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

Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/15/2016
Publication Date: 1/21/2016
Citation: Kesoju, S., Greene, S.L., Martin, R.C., Kramer, M.H. 2016. Update on RR gene flow research. Symposium Proceedings. Proceedings of Washington State Hay Growers Conference, Kennewick, WA. January 20-21, 2016.

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. Because of this, many alfalfa producers are impacted by market sensitivity to adventitious presence (AP) of GM traits. Our objective was to quantify the extent of gene movement from GM seed fields to commercial conventional seed fields on a landscape level. We found that distance between RRA and CON seed fields needs to be 330 m, to ensure 95% of CON seed samples are below the 0.9% detectable level. Further distances reduced the percent of positive samples. For GM and CON fields separated by 602 m, 95% of the samples had AP below 0.5%, and at 2441 m, 95% of the samples had AP below 0.1%.Establishing isolation distances to ensure coexistence of GM and non GM 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 isolation distances needed to ensure various AP thresholds in Walla Walla County, WA. Although we did not report our results here, we did find that adding explanatory variables to our model could reduce isolation distances. From the perspective of seed producers, distance is the most simple 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. Because of this, many alfalfa producers are impacted by market sensitivity to adventitious presence (AP) of GM traits. Our objective was to quantify the extent of gene movement from GM seed fields to commercial conventional seed fields on a landscape level, to define GM pollen dispersion distance and to provide industry with information to support coexistence strategies. In 2013, roundup ready alfalfa (RRA) and conventional (CON) seed fields were mapped in the Touchet Valley, WA. CON seed was harvested from 14 sink fields. The following explanatory/independent variables were obtained: distance of sample from closest RRA seed fields, closest alkali bee bed, LCB domiciles in closest CON and RRA seed fields; # of domiciles in RRA and CON fields, # of AB, LCB and native pollinators in RRA and CON fields; area of RRA source fields; area of CON sink fields; distance to riparian area, distance to open-range area; elevation; slope; and aspect. Seed and original seed were assessed for % AP using a seedling germination assay. % AP was transformed to the logit scale. The relationship between AP proportion and distance to RRA source fields at 0.1%, 0.5%, and 0.9% AP threshold levels were modeled using a quadratic regression. AP was detected in the original seed lots used to plant the CON seed fields sampled, but levels were within the company standards. We found that distance between RRA and CON seed fields needs to be 330 m, to ensure 95% of CON seed samples are below the 0.9% detectable level. Further distances reduced the percent of positive samples. For GM and CON fields separated by 602 m, 95% of the samples had AP below 0.5%, and at 2441 m, 95% of the samples had AP below 0.1%.