Super spud on menu as genetic code is cracked

The full genetic code of the potato plant has been deciphered by scientists who say that it will lead to the rapid development of new disease-resistant varieties of the world's most important non-cereal food crop.

Potatoes: who eats them and who grows them. Click here to download graphic (73k)

An international consortium of research organisations has sequenced the 840 million DNA "base pairs" that make up the 12 chromosomes of the potato genome. The breakthrough should lead to the identification of important genes that confer resistance to potato diseases such as late blight, a fungal infection that triggered the Irish potato famine of 1845.

It takes 10 to 12 years to breed a new variety of potato, but knowing the genome could cut the time by half and improve the end product by targeting the individual genes responsible for the desired traits, the scientists said.

"Anything that allows us to link genes with traits now will improve the rate at which we can produce a whole range of varieties by different methods," said Professor Iain Gordon, of the James Hutton Institute in Dundee, which took a lead role in the project. "We now understand, in effect, the book of life of the potato, we understand the genes and we can relate that to the traits that the potato has, to improve its productivity and to reduce the impact of pests and pathogens."

Each year some 200 million tons of potatoes are eaten worldwide and they form the fourth-largest staple crop after rice, wheat and maize. The rice genome was completed in 2005 – the first of a crop plant – and a draft sequence of wheat was published last year. Unlike cereals, potatoes are rich in nutrients such as vitamin C and folic acid and are seen as a critical crop in the effort to boost food production for a growing world population – expected to increase from to nine billion in the next 40 years.

Professor Robbie Waugh, also of the James Hutton Institute, said that cross-breeding domestic potato varieties with wild varieties that grow in South America had improved disease-resistance but success has been limited because these introduced traits tended to break down over time.

"The potato has been bred here for probably less than 400 years," Professor Waugh said. "Despite all the effort, we still grow potato varieties that are over 100 years old. Potato improvement is a very slow process. What the potato genome allows us to do is to identify particular genes that most potatoes have that may have a unique function, such as a resistant gene that is unique to a certain variety to potatoes. It could be transferred using genetic technology to a well-known cultivar grown today."

Growing popularity: a short history of the potato

* Domesticated between 7,000 and 10,000 years ago by the natives of southern Peru in South America, where the potato grows in the wild on the slopes of the Andes.

* In 1536, Spanish conquistadors take potatoes grown by the Inca back to Europe to impress royalty.

* The word "potato" is derived from the Spanish "patata", which is a compound of the native words "batata" and "papa".

* In 1538, Sir Francis Drake and the astronomer Thomas Harriot were credited with bringing the potato from the Americas to Britain, where it was quickly found to grow well in the cool, damp climate. By the 19th century it had established itself as the staple crop that fed the workforce driving the Industrial Revolution.

* French scientist Antoine Parmentier in 1774 discovered the nutritional benefits of the potato which lead to the plant's promotion in France.

* The potato crop of Ireland was devastated by the late blight fungus in 1845, triggering the Irish potato famine.

* In 1995, the potato became the first crop plant to be grown in space.