So far as the public is concerned, things have been quiet on the genome front since the great celebrations in 2003 when 13 years of work to sequence human DNA was completed. The result was a map of the 20,000 or more genes found in the 23 pairs of chromosomes which are the blueprint for the life of Homo sapiens. In the interim, scientists have sequenced the genes of a wide range of living things, from monkeys and chimps through cats and dogs to mice and rice. But now they have sequenced something which is three times as complex as the human genome and which could lead to cheaper bread throughout the world within just five years.
Wheat is the world's most important crop. Its genome is particularly complex because the swollen grain, which covers two million hectares of agricultural land across the globe, is a combination of three different wild grasses with three different genomes. Modern wheat crops can be traced back to wild wheats that grew in the Middle East some 10,000 years ago. A cross-breed between these plants was stumbled across by some prehistoric farmers, who found it so high-yielding that it was largely responsible for the displacement of hunter-gathering as the world's dominant way of life.
In the years since, farmers have repeatedly selected for higher yields and better disease resistance. The improvements have been such that yield has increased from around three tonnes per hectare in Roman times to a norm of eight tonnes today. The sequencing of the wheat genome could now mean that those yields will rise again significantly. The atlas of the wheat genome which British scientists have produced will allow crop- breeders to look for signposts that point to certain genetic traits and then concentrate on isolating them to increase qualities such as yield and drought resistance, and, perhaps most significantly, resistance to pathogens like wheat fungi which have traditionally evolved faster than breeders could produce wheat varieties resistant to them.
This is a cause for major congratulation. First, because of the achievement of a number of groups of British scientists working together, funded by the British taxpayer, to crack the wheat code. But second because the scientists are placing all their research on the internet, as what the scientific community calls "open-source information", to allow researchers anywhere in the world to join in the task of producing new and better varieties of wheat. The task is a huge one. The world's population is growing so that there are an extra six million mouths to feed every year. The global demand for food is expected to increase by 50 per cent by 2030.
But though today's breakthrough will rapidly accelerate conventional crop-breeding techniques, there will eventually come a point where the plant cannot be improved significantly further. The other breakthrough that sequencing the wheat genome will allow is that it will bring nearer the possibility of genetic modification.
That prospect will divide opinion. Opponents of GM crops raise questions of public safety and environmental risk; GM foods might have adverse effects on human health, they say, and they could threaten biodiversity by driving out other plants and the wildlife that depend on them. Enthusiasts for GM denounce that as a Luddite folly endorsed by politicians scheming to keep cheaper food imports out of Europe, which will in turn help keep EU farmers in jobs. GM foods, they say, will eventually be the only way to build food security for the poorest and most vulnerable people on earth.
The decision on GM is not one which the world can put off indefinitely. It will require some serious science to confront the untested prejudices which so often characterise the debate. But it is a decision which the sequencing of the wheat genome has just brought significantly closer.Reuse content