Spud U dislike


By Andy Coghlan and Kurt Kleiner BACKERS of genetically engineered crops faced a fresh barrage of negative publicity last week, as new findings emerged linking altered plants with threats to human health and the environment. At a meeting of the Ecological Society of America in Baltimore, Allison Snow of Ohio State University in Columbus reported that weeds in a laboratory became as hardy as their natural relatives when they acquired a gene for herbicide resistance from neighbouring genetically engineered crops. The received wisdom had been that weeds would become weaker than their natural relatives if they acquired the gene. Snow crossed a herbicide-resistant strain of canola or oilseed rape ( Brassica napus) with the related weed Brassica rapa. The offspring inherited the herbicide resistance, and within three generations produced a weed that retained the herbicide resistance and was otherwise as fit as normal weeds. Such weeds could quickly dominate fields being treated with the herbicide. But the results that caused most alarm came from experiments in Scotland by Arpad Puztai at the Rowett Research Institute in Aberdeen. In the British documentary World in Action, Puztai described the first evidence that genetically engineered foods might harm consumers. Puztai and his colleagues gave potatoes a gene from the South American jack bean (Canavalia ensiformis) and fed them to rats for 110 days. The rats weighed less than normal, and their immune systems had only half their normal activity. But the product of the jack bean gene, concanavalin A, has long been known to be harmful. It is one of many toxic proteins called lectins with which plants defend themselves against insects. Other lectins include ricin, the poison used on an umbrella tip to kill Bulgarian dissident Georgi Markov in 1978. Iain Cubitt, chief executive of Axis Genetics in Cambridge, was alarmed by the publicity given to the findings. “Everyone has known for years that concanavalin A is toxic, so if you put this in a potato and it ends up toxic, why is that such a surprise?” he says. “What do we learn by doing it?” Even the Rowett Institute was surprised by the response to the findings. “I think there’s been a gross overreaction,” says Philip James, the institute’s director. He says the work is part of a screening programme to pick up any safety hazards that might have been overlooked. Monsanto, the world’s largest agricultural biotechnology company based in St Louis, Missouri, expressed disappointment that the Rowett work had caused so much panic, given the known toxicity of concanavalin A. “This is no great surprise,” says a spokesman. Monsanto has no plans to insert insect-fighting lectins into plants. However, not all Puztai’s experiments were as negative. Puztai showed that rats appeared normal after eating potatoes equipped with a lectin from the snowdrop (Galanthus nivalis). The lectin kills aphids and has been successfully inserted into a number of experimental crop plants, including potatoes (Technology, 6 January 1996,
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