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Research Project: Plant and Microbial Genetic Resource Preservation and Quality Assessment

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Title: Roadside alfalfa: Innocent bystanders or conveyers of genetically-engineered traits?

Author
item Greene, Stephanie

Submitted to: Progressive Forage Grower
Publication Type: Trade Journal
Publication Acceptance Date: 2/19/2016
Publication Date: 4/1/2016
Citation: Greene, S.L. 2016. Roadside alfalfa: Innocent bystanders or conveyers of genetically-engineered traits? Progressive Forage Grower. 4:26-27.

Interpretive Summary: Clumps of alfalfa are a common sight along roads and vacant lots in areas that grow alfalfa for hay or seed. So what role do feral roadside plants play in dispersing transgenes? Is there a risk that transgenic feral plants serve as reservoirs or conduits that might facilitate the movement of transgenes into conventional alfalfa? Are there environment and agricultural factors that influence feral plant occurrence, and importantly, transgenic feral plant occurrence? We report on efforts to better understand these issues. In 2011 we conducted a roadside survey in Fresno County, California, Canyon County, Idaho and Walla Walla County, Washington- three important alfalfa seed producing areas. We travelled 6000 km of rural roads, stopping at 4,190 random sites to look for feral alfalfa plants. Generally, feral plants were rare. Across study areas, 4.4% of our random sites contained feral populations. None of the environmental, climatic or production variables we examined appeared to influence where feral plants occurred. Although feral plants were rare, they were readily found in seed and hay production areas, and multiple lines of evidence suggested that they can serve as conduits for transgene movement. In Fresno County 32.7% of sites having feral plants, had transgenic feral plants. In Canyon and Walla Walla counties, we found 24.7%, and 8.3% of feral sites had transgenic plants. We tended to find transgenic feral plants at locations where the probability of seed escape was high, such as adjacent to original GE seed fields, or on roads used to transport GE seed to conditioning plants. We were unable to detect adventitious presence in conventional seed fields adjacent to transgenic feral plants in Fresno. However, if grower adoption rates match those of GE cotton, soybean, corn and oilseed rape, the occurrence of transgenic feral populations will increase, and negative consequences may become evident at some point. To ensure the coexistence of neighbors growing alfalfa for GE, non GE and GE-sensitive markets, all producers should be concerned about minimizing GE seed spillage and controlling feral plants.

Technical Abstract: Clumps of alfalfa are a common sight along roads and vacant lots in areas that grow alfalfa for hay or seed. So what role do feral roadside plants play in dispersing transgenes? Is there a risk that transgenic feral plants serve as reservoirs or conduits that might facilitate the movement of transgenes into conventional alfalfa? Are there environment and agricultural factors that influence feral plant occurrence, and importantly, transgenic feral plant occurrence? We report on efforts to better understand these issues. In 2011 we conducted a roadside survey in Fresno County, California, Canyon County, Idaho and Walla Walla County, Washington- three important alfalfa seed producing areas. We travelled 6000 km of rural roads, stopping at 4,190 random sites to look for feral alfalfa plants. Generally, feral plants were rare. Across study areas, 4.4% of our random sites contained feral populations. None of the environmental, climatic or production variables we examined appeared to influence where feral plants occurred. Although feral plants were rare, they were readily found in seed and hay production areas, and multiple lines of evidence suggested that they can serve as conduits for transgene movement. In Fresno County 32.7% of sites having feral plants, had transgenic feral plants. In Canyon and Walla Walla counties, we found 24.7%, and 8.3% of feral sites had transgenic plants. We tended to find transgenic feral plants at locations where the probability of seed escape was high, such as adjacent to original GE seed fields, or on roads used to transport GE seed to conditioning plants. We were unable to detect adventitious presence in conventional seed fields adjacent to transgenic feral plants in Fresno. However, if grower adoption rates match those of GE cotton, soybean, corn and oilseed rape, the occurrence of transgenic feral populations will increase, and negative consequences may become evident at some point. To ensure the coexistence of neighbors growing alfalfa for GE, non GE and GE-sensitive markets, all producers should be concerned about minimizing GE seed spillage and controlling feral plants.