(Embargo, 6pm Sunday - Nature magazine)

A complete genetic map of the potato has been developed by research groups around the world, the scientific journal, Nature, reports today.

Almost two years ago, a draft 'blueprint' was published but now the complete DNA map has been charted by 16 groups working in 14 countries including the UK and the United States.

The international consortium will enable plant breeders to produce commercial varieties, potentially with drought tolerance or resistance to costly diseases including blight or potato cyst nematodes.

Dr Mike Storey, head of research and development for Potato Council, said: 'This could result in more efficient use of fertilisers, herbicides and pesticides, helping growers minimise cultivation costs whilst maximising sustainable yields.'

The new 'street map' could identify useful genes for the future, which might avoid the need for repeat crop spraying to protect plants from late blight, which costs Britain's growers about �60m a year. Blight caused huge loss of life in the mid 19th century in the Irish Potato Famine.

The work was carried out by the Potato Genome Sequencing Consortium and involved scientists at the James Hutton Institute, Scotland, the University of Dundee and Imperial College, London.

The consortium involved 16 research groups in 14 countries including Argentina, Brazil, China, Chile, India, Netherlands, New Zealand, Peru, the UK and the USA.

After wheat and rice, potato is the third most important food crop, with a world-wide production of 309m tonnes in 2007. By 2020 it is estimated that more than two billion people worldwide will depend on potato for food, feed, or income.