Submitted to: Council for Agricultural Science and Technology Issue Paper
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2007
Publication Date: 12/1/2007
Citation: Gealy, D.R., Bradford, K.J., Hall, L., Hellmich Ii, R.L., Raybould, A., Wolt, J., Zilberman, D. 2007. Implications of gene flow in the scale-up and commercial use of biotechnology-derived crops: Economic and policy considerations. Council for Agricultural Science and Technology Issue Paper. Issue Paper 37. CAST, Ames, Iowa. 24 p. Interpretive Summary: Biotechnology-derived crops (a.k.a. ‘genetically modified’ or ‘GM’ crops) were first commercialized in 1996. By 2005 their global production had expanded to 225 million acres in 21 countries. The US continues to be the largest producer of GM crops, but developing countries now grow more than one third of all GM crop acreage. Outcrossing (usually via pollen dispersal) between plants of the same or closely related species (e.g. weedy relatives) can lead to low levels of gene exchange between plants from one generation to the next or between plants that are physically separated. When these changes are maintained over time, we say that ‘gene flow’ has occurred. Although there has been recent interest in understanding and/or reducing gene flow in GM crops, this is a natural phenomenon that is common in non-GM crops as well. This paper 1) reviews the existing health and environmental evaluation systems already in place for GM crops in the US; 2) evaluates the potential for gene flow from existing GM crops and other important food crops; 3) reviews the biological traits that are presently being introduced into crops using biotechnology and conventional approaches; 4) evaluates the potential impacts of gene flow from GM crops to weedy relatives; 5) discusses potential economic and trade ramifications in the US from presence of low-levels of GM materials in grain or other commodities; 6) and reviews sound approaches for successful coexistence of GM, conventional, and non-conventional crop production and trade.
Technical Abstract: Worldwide, the area planted to biotechnology-derived crops (i.e. ‘genetically modified’ or ‘GM’ crops) has expanded rapidly, increasing more than fifty-fold since first commercialized in 1996. In 2005, GM crops expanded to 90 million ha and were produced in 21 countries on six continents. The US is the largest producer of GM crops, but developing countries (principally China, India, Argentina, Brazil and South Africa) now grow more than one third of all GM crops globally. Outcrossing between sexually compatible plant species can lead to low levels of gene flow within and among different plant populations or species (including wild and weedy relatives of crops). Gene flow is the movement of genes between individuals, generations, and across spatial dimensions. Although there is great public interest in understanding and managing gene flow in GM crops, this phenomenon occurs commonly in conventional crops as well and is nearly universal in the biological world. This paper reviews the existing health and environmental assessment/regulatory mechanisms used for GM crops in the US, reviews the potential for gene flow from commercial GM crops and other important world food crops, describes the types of biological traits being imparted into GM crops and their potential interactions with gene flow, reviews the prevalence and potential impacts of gene flow from GM crops to weedy relatives, discusses US economic and trade ramifications of gene flow-derived GM materials in the global marketplace, evaluates potential benefits of establishing threshold levels for GM materials in agricultural commodities, and summarizes approaches for successful coexistence between GM, conventional, and non-conventional crop production systems.