Taste of things to come: the apple gene that will put the bite on foreigners

The apple of the future could be tastier, crunchier, keep longer and be better for you, thanks to genetic engineering. British scientists are mapping out the 50,000-odd genes which determine all the characteristics of an apple, and trying to pick out the ones which determine taste and texture.

The aim is to help British growers fight off foreign imports - notably the notoriously tasteless, yet inexplicably successful French Golden Delicious.

"We have made a major leap forward in the past five years, in terms of finding out what genes control what in terms of apple quality," said Dr Graham King, of Horticulture Research International.

The team has produced about 300 genetic "markers" for the apple's 17 chromosomes, splitting them into regions where relevant genes may lie.

The taste and texture of an apple is the result of a complex intermingling of chemicals. The most evident aspect of taste - the combination of sweet and tart - comes from the balance of sugars and malic acid present. The more acid and fewer sugars there are, the stronger the flavour, and the more likely that it will be retained after cooking (as happens with the Bramley cooking apple).

"There's more acid in a Cox's than a Golden Delicious, for example," said Dr King. "It's the same gene that eventually produces acid, but its action is modified by another one. Maybe we could, if we wanted, make Golden Delicious apples more acid, and so tasty." It would simply be a matter of turning the relevant genes on or off - as has been done by the biotech company Zeneca in genetically-engineered tomatoes, to make them slower to ripen and rot.

But trying to tweak an apple's characteristics further could be an enormous task that dwarfs any kitchen recipe. Though an apple is more than 80 per cent water, its overall aroma is a subtle blend of 250 volatile organic compounds such as esters, alcohols, aldehydes and essential oils.

Picking out the genes which control the balance of those elements is a difficult task, but one which could be essential in growing the fruits for the next millennium.

Once fruits' genes are mapped, probably in the next 10 or 20 years, there is in theory nothing to prevent genetic technology from creating apples that taste like pears or grapes or any other fruit, said Dr King.

"People will start seeing the effects of our work now in about 10 to 15 years' time. Technology is going to make incremental changes leading to designer apples."

Professor Donald Grierson, at the school of biology at the University of Nottingham, increasingly sophisticated genetic matching techniques will be able to pinpoint the essential genes required to produce the ideal apple. "It's a complementary approach to the Horticultural Research team's," he said yesterday. "You find out what enzymes are causing something, such as a taste or smell or ripening, and then you look for the gene which is at its root.

"Simply sequencing the whole DNA of a fruit or plant could take 10 or 20 years. This approach has the potential to give greater precision, more quickly, and potentially to produce a more novel product."

But the key to success will lie in allowing consumers to decide if they want such foods, by labelling them clearly. "What we have learnt in the past five years is that the public is quite alarmed when they first hear about genetically-modified food, particularly if it's under a headline like `Frankenstein food threatens consumers'," he said. "But if you explain then people are interested, and ask who gets the advantage. And then if it's labelled so that they can choose, they're happy.