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GM wheat that wards off aphids trialled in UK

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Peppermint gene inserted into the DNA of wheat strain in attempt to produce crop that emits pheromone odour signals

A peppermint gene has been used to engineer a wheat strain that sends out chemical messages to scare off aphid pests.

In future, it may be possible to cut the use of pesticides on plants modified with the gene.

The genetic modification harnesses one of the plant world's own defence mechanisms, the ability to ward off pests with pheromone odour signals.

Peppermint produces a smell, undetectable to humans, which mimics an alarm signal generated by aphids when they are attacked by predators.

This helps deter the insects, which suck sugar out of plants and cause global crop damage costing billions of pounds each year.

The British scientists took the peppermint gene responsible and inserted it into the DNA of a spring wheat strain.

Eight test plots of the wheat, measuring six metres square, are now growing at the Rothamsted Research agricultural institute in Hertfordshire.

The plots are protected by fences and ditches, both to keep away animals that might damage the plants and anti-GM protesters.

Scientists will watch the plants closely over the summer to see if their performance matches what is predicted by laboratory studies.

Previous work suggests the pheromone will not only drive large numbers of aphids away but also attract parasitic wasps, one of the insects' biggest natural enemies. The tiny wasps lay their eggs in the aphids, which are then eaten by the hatching grubs.

An added bonus is that aphids spread viruses that infect and kill plants, so the wheat is protected from disease, researchers said.

Speaking at a news briefing at the Science Media Centre in London, Professor John Pickett, head of chemical ecology at Rothamsted Research, said: "Insects use pheromones to communicate with each other.

"Aphids use an alarm pheromone which when they're attacked by ladybirds and parasitic wasps causes them to disperse.

"Since we started working on this in the early 80s we have tried various ways to deliver the alarm pheromone.

"You can synthesise it, you can make it as a chemical, you can get it from plants.

"The best way is to engineer the crop plant itself so it releases it, pure, the same way the aphid releases it when it's attacked.

He hoped that in time the technology would benefit the farming community and produce a saleable product. However, at present, the work was purely a research project with no plans for commercial development.

Wheat worth £1.2bn is grown in the UK each year. Without pesticides, it is estimated that around £100m of that would be lost to aphids.

Professor Maurice Moloney, chief executive of Rothamsted Research, said the new research marked a change of approach to GM.

"Generally, GM has been used to kill something," he said. "You've either got to kill the weeds or you kill the insects. In this case we're copying nature. What we're really doing is putting a no-parking zone on every leaf of the plant saying: 'Don't come here, because this is not a place you want to be.'"

The GM field trial is one of only three currently taking place in the UK.

GM crop development is highly restricted in Europe, in contrast to some other countries such as the United States.

A GM maize from the biotech company Monsanto cultivated in Spain is currently the only GM food crop licensed to be grown in the EU, and is chiefly intended for animals. A small number of GM potatoes are also grown for starch production, not food.

All food companies and supermarkets in the UK and EU have a no-GM policy.

Pete Riley, from the anti-GM group GM Freeze, said there could be unpredictable risks attached to the research."We've got a number of concerns about this development," he said.

"There's already evidence from biological studies that if you expose aphids to this particular pheromone for any length of time they get habituated to it and ignore it. Insects adapt quite quickly."


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