Submitted to: International Symposium on the Biosafety of Field Tests of Genetically Modi
Publication Type: Proceedings
Publication Acceptance Date: 9/15/2004
Publication Date: 9/26/2004
Citation: Oliver, M.J., Luo, H., Kausch, A., Collins, H. 2004. Seed-based strategies for transgene containment. International Symposium on the Biosafety of Field Tests of Genetically Modified
Technical Abstract: In order to feed the burgeoning world population, estimated to reach 9 billion by the year 2050 (U.S. census Bureau), agriculture must respond by tripling its net production of food and fiber from present day levels. Such a large increase in production must also occur without expanding the current acreage used for production (FAO, 1996) as all truly cultivatable land is now in use and any expansion would necessitate the destruction of our forests and wilderness areas. In the 20th century the world was faced with a similar need to triple agricultural output, a need that gave birth to the Green Revolution a very successful program of conventional breeding and the brain child of Dr. Norman Borlaug. The Green revolution is not over and has still much to contribute in the 21st century, but, as pointed out by Dr. Borlaug, 'for genetic improvement of food crops to continue at a pace sufficient to meet the needs of the 8.3 billion people projected to be on this planet at the end of the quarter century, both conventional technology and biotechnology are needed' (Borlaug, 2000). Biotechnology not only opens up the possibility of expanding available germplasm by the introduction of novel genes but also promises to accelerate the process of generating useful varieties that can expand yield expectations and lower production costs. Biotechnology also offers the promise of developing production systems that reduce the impact of farming practices on the surrounding environment by reducing herbicide and pesticide use and perhaps in the future reducing the reliance on artificial fertilizer for crop productivity. However, it is the very nature of these technologies that have led to concerns about the possibilities that the transgenes that confer herbicide and pest resistance may escape into related crop plants (where the trait may be undesirable) or non-crop sexually compatible species (giving them a selective advantage). The main fear is that at some point a 'superweed' may arise that would act in a fashion similar to the invasive noxious weeds that have arisen from accidental introduction into susceptible ecosystems. There are also concerns that the GM crop itself could become persistent or weedy in non-agricultural natural habitats from seed dispersal. This is not a fear simply associated with the introduction of GM crops; this same fear also resides when conventional breeding introduces new resistance traits. With the increased interest and concerns for the biosafety of crop modification, efforts to prevent gene flow from modified crops have taken center stage in the biotech industry. In flowering plants, gene flow can occur through movement of pollen grains and seeds, with seeds ultimately producing plants that again contribute pollen to the process of gene flow. In this report we will focus on genetic strategies for transgene containment that targets gene flow primarily through the seed. Although the strategies discussed here are seed based, they have the added advantage of operating to prevent gene flow via pollen dispersal and thus may, perhaps, be better described as complete containment strategies.