GM crops are unsafe, right?
crosses between genetically modified (gm) oilseed rape and a wild relative produce hybrid plants that are as toxic to insects as the original crop. Though it is still unclear how such hybrids fare in the wild, the finding is likely to be seized on by environmentalists as proof that field trails of gm crops are unsafe.
During laboratory experiments, Matthew Halfhill at the Greensboro-based University of North Carolina and colleagues took oilseed rape (canola) modified to contain the insect-resistance gene Bt and crossed it with a related weed, birdseed rape (Brassica rapa). They made 11 crosses using different combinations of plant lines. Five of them produced stable hybrids containing the Bt gene. These expressed insecticide produced by the gene at levels similar to the gm parent and were highly toxic to insects.
The finding will fuel fears that 'superweeds' containing foreign genes might spread rapidly. But no one knows how much of an edge resistance would give the hybrids as against non- gm relatives. "Without doing ecological experiments, your guess is as good as mine," says Brian Johnson, biotechnology adviser to the England-based conservation agency English Nature.
Some researchers believe that the spread of birdseed rape can be stopped by enhancing competition with other plants. Moreover, one reason Bt-oilseed rape is not grown commercially even in countries that allow gm crops is that pests do not have a serious impact on oilseed rape. Therefore, experts assert that genetically modifying the crop is an unwarranted risk.
Crosses between oilseed rape and birdseed rape are well documented, but this is the first evidence that the Bt gene might pass to the hybrid. "This demonstrates that hybrids can and will be formed and that they will have insecticidal activity," says Johnson. He says this underlines the importance of investigating the environmental consequences before gm rape is released in the environment on a commercial scale.
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