By Ben Hirschler

Scientists believe they have found a way to map the hugely complex genetic
code of wheat, the staple food for 35 percent of the world's population.
The move could lead to improved crop varieties that are resistant to
drought and disease at a time when surging demand has stoked fears over
future grain supply, sending prices soaring to record highs earlier this
year.

French scientists said on Thursday they had constructed a map of the largest
wheat chromosome, chromosome 3B, and demonstrated it should be possible to
sequence the plant's entire genetic code.

"We hope that in the next five years we will have the physical map for the
whole genome," Etienne Paux of the Institut National de la Recherche
Agronomique in Clermont-Ferrand told Reuters.

In the past, the wheat genome has been viewed as all but impossible to
sequence because of its sheer size. It comprises 17 billion base pairs of
the chemicals that make up DNA - five times more than the human genome.

The 3B chromosome alone is more than twice the size of the entire genome of
rice, which was the first major food crop to be sequenced six years ago.

Once the whole wheat genome is sequenced, researchers say it will be much
easier to identify genes that can be used either in conventional plant
breeding programs or to develop genetically modified crop varieties.

"We can now really accelerate the identification of regions involved in
agronomically important traits," Paux said.

"It will increase our development of new varieties and in future it may take
only four to six years instead of 10 or 12 years to develop new varieties."

To date, the work on the wheat genome is being funded in universities and
government institutes under the auspices of the International Wheat Genome
Sequencing Consortium.

But Paux said commercial seed companies, like Monsanto and Syngenta, might
start to become involved now that the viability of sequencing wheat, or
triticum aestivum, had been established.

Scientists, meanwhile, are already using the genetic data collected so far
by Paux and his colleagues, with a team in Australia homing in on a gene
involved in resistance to an alarming new form of stem rust.

The relatively new and aggressive strain of black stem rust, called Ug99
after its discovery in Uganda in 1999, has spread in East Africa and parts
of the Middle East. Worryingly, most commercial wheat crops have no
resistance.

The new research on the wheat genome by Paux and his colleagues was
published in the journal Science.
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