Innovation: Scientists engineer a fruitful harvest

THE FIRST field trial of genetically engineered wheat will reach fruition next week when the crop is harvested from fields near Great Abington in Cambridgeshire.

For biotechnologists, this marks the end of 10 or more years of trying to find a way of introducing new genes with commercially valuable characteristics, such as salt tolerance or drought resistance, into one of the world's most important food crops.

The standard gene transfer method, infecting plants with bacteria which carry the foreign genes, does not work with wheat and other cereal crops.

So the Cambridgeshire test wheat was altered by a newly developed technique, in which plant cells are bombarded with microscopic gold balls coated with the gene material DNA.

One of the three wheat types growing near Great Abington has a red pigment gene taken from wild Peruvian maize which gives the grains red husks. Although there is absolutely no commercial value in this, it is a visible sign that the DNA bombardment technique works, according to David Thompson of New Farm Crops, part of Ciba Seeds, which is staging the trials.

The two other types of wheat produce enzymes that can be detected by simple laboratory tests. 'These trials have proved that the genes are in the plant, they are stable and they are expressed,' Mr Thompson said.

Now it has shown that the technique works, Ciba will move on to introducing commercially important genes at its Agricultural Biotechnology Research Unit in North Carolina, US, where the wheat plants were developed and tested in the laboratory and greenhouse.

Earlier this year, the British company Zeneca announced it had developed another, simpler method for introducing genes into cereals. A common chemical, silicon carbide, which has a crystalline structure, is shaken with water, plant cells and DNA. The crystals pierce the plant cell walls, enabling the foreign genes to enter.

Zeneca is now collaborating with researchers at Maff and the Biotechnology and Biological Sciences Research Council in a pounds 1m project, based at the Rothamsted Experimental Station in Hertfordshire, to develop genetic engineering systems for wheat.

Their work, and that of scientists worldwide who are trying to genetically engineer cereal crops, will be helped by the most significant discovery yet in this field, announced in April.

British and Japanese scientists have shown that different cereals, including rice, wheat, barley, rye, maize and sorghum, have similar genes arranged in in each case in the same sequence. This means that once genes for important characteristics are identified in one cereal, they can be inserted into another employing the latest techniques.

'If I had stood up two years ago and said this was likely, I would have been laughed at,' said Graham Moore, who made the discovery with Mike Gale and colleagues at the John Innes Research Centre in Norwich, working in collaboration with scientists on the Japanese Rice Genome Research Programme.

This is because, although all cereal plants are thought to come from a common ancestor, over 60 million years they have evolved into thousands of species which vary enormously in their overall genetic characterisics, or genomes. At one extreme is wheat, with six times more DNA than humans, and at the other is rice, with only 4 per cent as much DNA as wheat. It turns out that much of the genetic material in wheat is made up of what is termed junk DNA, which appears to have no role in the plant's development and growth.

'Until now wheat has been intractable to genetic analysis because of the problems of targetting genes in the large genome,' Mr Moore said. 'Now we can use rice as a model for wheat and all other cereals.'

This will allow scientists around the world, working on different species, to pool their findings. The Japanese rice programme has already mapped and published half of the 30,000 genes in rice, and this data can now be applied to all cereal crops, which together provide more than half of world's food.

Ciba is the only company to have genetically engineered wheat in field trials, but in the laboratory researchers are now starting to use the new techniques to transfer useful genes. In the UK, the Institute of Arable Crops Research is bombarding wheat with genes that will increase gluten production and improve its bread-making potential.

Paul Lazzeri, who heads the Rothamsted project, thinks another early target might be genes that control nitrate movement within wheat, increasing the plant's efficiency in using nutrients and allowing farmers to use less nitrate fertiliser. Other targets are inducing drought, heat and salt tolerance, so that the range of wheat and other cereal crops can be extended, and introducing disease resistance.

(Photograph omitted)