Expert Commentary

Transgene flow in cotton seed production fields

2010 study by the University of Arizona on the reasons for gene flow between fields planted with genetically modified cotton and those with traditional varieties.

Transgenic crops are grown on more than 300 million acres of farmland around the world. In the United States 94.6% of the cotton planted is genetically modified, commonly to resist pests, pesticides or both. Given the dominance of some transgenic crops, concerns have been raised over the power of companies that control GM seeds as well the potential for gene flow between modified and conventional varieties.

Because corporate owners of transgenic seeds hold copyright over their seeds, lawsuits often result when modified plants are found in conventional fields. Concerns have been raised that traditional farmers and their crops are at a disadvantage as transgene flows further complicate the legal landscape.

To better understand the causes of unintended gene flow between insect-resistant Bt cotton and neighboring conventional crops, in 2010 entomologists at the University of Arizona conducted a study, “Pollen- and Seed-Mediated Transgene Flow in Commercial Cotton Seed Production Fields.” The study was published in PLoS ONE, a peer-reviewed, open-access online publication.

The study’s results include:

  • More than 15% of all observed transgene flow was the direct result of planting error or mislabeled seed bags.
  • Only 1% of adventitious Bt cotton presence could be attributed to pollen-mediated gene flow.

“Given the low rates of pollen-mediated gene flow observed in this study,” the researchers write, “careful planting and screening of seeds could be more important than field spacing for limiting gene flow.”

Tags: safety, technology, genetically modified organisms (GMO)

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