Going wild

Weeds become stronger after accidentally acquiring genes from genetically engineered crops

Published: Sunday 15 September 2002

for the first time, a study has demonstrated that foreign genes from a genetically modified (gm) crop plant can migrate into weeds and make them stronger. The study was conducted by researchers from three us universities, including the Ohio State University. To conduct the study, the researchers used hybrid sunflowers containing a transgene from the soil dwelling bacterium Bacillus thuringiensis (bt) that produces chemicals toxic to certain species of insects. The researchers crossbred these with wild, non- b t sunflowers.

They found that the second generation of wild sunflowers contained the transgene, showing that the alien gene could be transferred. The researchers then concentrated on learning what effects the new gene would have on the wild sunflowers. These plants also suffered from far less insect damage, suggesting that the gene was preventing insects from eating the wild plants. Moreover, these wild flowers produced 50 per cent more seeds than plants without the gene. "We were surprised that a single transgene could have such a big effect on seed production," said Allison Snow, a study coauthor and a professor of evolution, ecology and organismal biology at Ohio State University. Furthermore, the researchers found that the addition of the bt gene did not harm the physical fitness of the weeds, even when the sunflowers were deprived of water and nutrients to mimic drought conditions. "There were no costs at all for the weeds to inherit the transgene," said Snow.

According to the researchers, the study indicates that many genetically modified crops could potentially crossbreed with weeds. "One possible fatal outcome of such transfer would be a population of 'super weeds', which could be resistant to both herbicides and insect attack," said Snow.

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