International research team cracks potato genome

[September 28, 2009]  DETROIT (AP) -- A global team of researchers has mapped the genetic code of the world's most popular vegetable -- the potato.

The draft of the potato genome released last week represents the work of more than 50 scientists from 16 institutions and will provide a starting point for other researchers to develop sturdier, more nutritious potatoes.

That's important because the potato is widely grown and plays a central role in feeding the world's 6.3 billion people, said Robin Buell, a Michigan State University plant biologist who worked on the project. The East Lansing school announced the results in the U.S.

"The potato is the most important vegetable worldwide," Buell said. "This report on potato (genes) is a major milestone in genome mapping."

The Potato Genome Sequencing Consortium began work in 2006. It has 16 institutional members in Argentina, Britain, Chile, China, India, Ireland, Netherlands, New Zealand, Peru, Poland, Russia and the United States. Michigan State and Virginia Tech are formal members of the consortium, and some work was done at the University of Wisconsin.

The potato genome has 12 chromosomes with 840 million base pairs, about a quarter the size of the human genome. The draft covers 95 percent of potato genes.

Launched by the Plant Breeding Department at Wageningen University in the Netherlands, the work took off with development of a new computer program at China's Beijing Genomics Institute. The computer program allowed researchers to more easily pool results of their work on chromosome segments to create a full genetic map.

As a researcher at the Institute for Genomic Research in Rockville, Md., Buell was part of a collaborative effort in 1999-2005 that mapped the gene structure of rice. A nearly complete genome map of maize, or corn, was announced in 2008.

A gene map allows quicker development of new crop strains. The rice genome map has already led to the development of a variety that can survive being submerged in water and is used in flood-prone Bangladesh, according to the International Rice Research Institute.

First cultivated in South America about 7,000 years ago, the potato is now grown on every continent but Antarctica. It's a close relative of the tomato.

Potatoes are the world's fourth largest food crop after three grains -- maize, rice and wheat. Farmers worldwide produced about 309 million tons of potatoes in 2007.

China is the world's largest consumer of potatoes at about 48 million tons a year. Per person, the world's leading potato eaters are in Belarus, where about 400 pounds are consumed annually for each resident. Americans eat about 120 pounds.

Potatoes are subject to a range of viral, fungal and bacterial diseases that attack them above and below ground.

Most notorious is the so-called "late blight" that attacks potato foliage. It was responsible for the potato famine of the 1840s that killed about 1 million people in Ireland and caused a mass emigration.

On Sept. 14, a scientific team announced success in mapping the genome of the late blight pathogen, which still causes billions of dollars in damage to potato, tomato and other crops each year.

"This is probably the most costly plant pathogen, per acre, that we've ever had to deal with," Oregon State University plant pathologist Nik Grunwald said in announcing that breakthrough.

Researchers hope the potato genome will lead to a major breakthrough in their ability to develop varieties resistant to late blight and other diseases, according to the Scottish Crop Research Institute, another consortium member.

"Currently potato breeding takes about 10-12 years to develop a new variety," the institute said in a statement. "It is expected that being able to use the genome information will dramatically shorten the time taken to breed new varieties as well as reducing the cost."

At Michigan State, Buell and crop scientist Dave Douches are putting the potato genome results to work as leaders of a $5.4 million U.S. Department of Agriculture-funded project to improve the quality, yield, drought tolerance and disease resistance of potatoes and tomatoes.

"The timing of the release of the potato draft sequence is nice," Douches said. "We're combining genetics and breeding, so having a draft of the genome will help us find genetic markers for desirable traits in potatoes, which will make breeding more precise."

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On the Net:

Potato Genome Sequencing Consortium: http://www.potatogenome.net/

[Associated Press; By DAVID N. GOODMAN]

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