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WHEN is a genetically modified organism not a genetically modified organism? When it doesn鈥檛 contain any foreign genes, claims Joachim Messing at Rutgers University in New Jersey.

Messing and his colleague Jinsheng Lai have created a variety of maize that produces nearly twice as much of the amino acid methionine as normal. Methionine is an essential nutrient for mammals, but ordinary maize contains little of it. The new variety could save farmers worldwide the billion dollars a year they spend on methionine supplements for maize-fed animals. And in poor countries where many people have a low-protein diet, it could reduce the incidence of methionine deficiency, which can cause liver damage, muscle loss and skin lesions.

To create the maize, Messing and Lai took the plant鈥檚 own gene for a protein that is rich in methionine, altered the DNA on either side to boost production and then put this modified extra copy back into maize.

The researchers say that modifications such as this, which simply change the levels of existing proteins, are likely to present fewer safety issues than adding foreign genes. (At the moment, their 鈥減rototype鈥� maize variety also includes a bacterial gene for herbicide resistance and a section of viral DNA, but future versions will not.)

Controversially, Messing argues that if the proteins involved are known to be safe, such plants shouldn鈥檛 have to undergo environmental and health checks. And he goes even further, claiming that the final version of the maize variety won鈥檛 be a genetically modified organism at all, because it won鈥檛 contain any foreign genes鈥攅ven though it has been created by exactly the same process as other GMOs.

鈥淚t quite clearly is,鈥� says Adrian Bebb of Friends of the Earth. He argues that there are still safety concerns because the addition of an extra piece of DNA, wherever it came from, could have unexpected effects on other genes.

But there are likely to be fewer problems compared with adding foreign genes. In 1996, for example, Pioneer-Hi-Bred abandoned a soybean variety with an added methionine-rich Brazil nut protein when the protein was shown to cause allergies.