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Wheat’s genetic code finally unlocked

Discovery may alter farming

By Raphael G. Satter
Associated Press / August 28, 2010

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LONDON — British scientists have decoded the genetic sequence of wheat — one of the world’s oldest and most important crops — a development they hope could help the global staple meet the challenges of climate change, disease, and population growth.

Wheat is grown across more of the world’s farmland than any other cereal, and researchers said yesterday that they’re posting its genetic code to the Internet in the hope that scientists can use it as a tool to improve farmers’ harvests. One academic in the field called the discovery “a landmark.’’

“The wheat genome is the holy grail of plant genomes,’’ said Nick Talbot, a professor of biosciences at the University of Exeter who wasn’t involved in the research. “It’s going to really revolutionize how we breed it.’’

University of Liverpool scientist Neil Hall, whose team cracked the code, said the information could eventually help breeders of varieties of wheat better identify genetic variations responsible for disease resistance, drought tolerance, and yield. Although the genetic sequence remains a rough draft, and additional strains of wheat need to be analyzed for the work to be useful, Hall predicted that it wouldn’t take long for his work to affect the field.

“Hopefully the benefit of this work will come through in the next five years,’’ he said.

Strands of genetic information — DNA — are the building blocks of life, and an organism’s genetic sequence is like an instruction book spelling out which block goes where. Decoding the entire sequence, known as the genome, gives unparalleled insight into how an organism is formed, develops, and dies.

Wheat is a relative latecomer to the world of genetic sequencing. This year marks the 10th anniversary of the date the human genome was laid bare. Other crops have had their genetic codes unscrambled within the past few years — rice in 2005, corn in 2009, and soybeans earlier this year.

The reason for the delay in analyzing wheat’s genetic code, Hall said, was that the code is massive — far larger than corn or rice and five times the length of the one carried by humans.

One reason for the outsize genome is that strains such as the Chinese spring wheat analyzed by Hall’s team carry six copies of the same gene (most creatures carry two.) Another is that wheat has a tangled ancestry, tracing its descent from three different species of wild grass.

But sequencing techniques have improved dramatically over the past decade. The process used in this case is called pyrosequencing, which Hall said allowed his team to monitor a million strands of DNA at a time. He said the sequence took about a year to compile.

Although the code may yet see use by genetic engineers hoping to craft artificial strains of wheat, Hall was at pains to stress the conventional applications of his work. Until now, breeders seeking to combine the best traits of two strains of wheat would cross the pair, grow the hybrid crop, and hope for the best.

Although the process has been used by farmers since wheat was first cultivated 10,000 years ago, Talbot described it as laborious and inefficient.

“Very often we were talking about 10 to 15 years of intensive breeding programs,’’ he said. “We’re talking now about doing things in less than five.’’

Talbot noted that rice cultivation had already benefited from the publication of its genetic code — and led to the development of vitamin-enriched and drought-resistant strains.

Alexander Evans, an expert in resource scarcity issues at New York University, welcomed the announcement but warned against putting too much faith in genetics. “We have to be very careful about saying that science will feed the world,’’ he said.

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