Scientists unveil genetic blueprint of bread wheat

An international team of scientists on Thursday unveiled a draft genome sequence of bread wheat, also known as common wheat, a scientific advancement that could help develop more productive or resistant wheat varieties.

Rich in protein, carbohydrates and minerals, bread wheat is one of the world's most important cereal grain crops, serving as the staple food source for 30 percent of the human population. The large, repetitive nature of the bread wheat genome, however, has made generating such a sequence difficult.

In a paper published in the US journal Science, the International Wheat Genome Sequencing Consortium (IWGSC), a group established in 2005 by wheat growers, plant scientists, and public and private breeders, presented a chromosome-based draft sequence of the bread wheat genome, by focusing their work on a cultivated wheat variety called Chinese Spring.

The researchers said the draft sequence allowed them to pinpoint the location of more than 120,000 genes, many of which relate to traits important to agriculture like grain quality, pest resistance, or abiotic stress tolerance. "The genetic blueprint is an invaluable resource to plant science researchers and breeders," the IWGSC said in a statement. "For the first time, they have at their disposal a set of tools enabling them to rapidly locate specific genes on individual wheat chromosomes throughout the genome."

The group believed that these results could lead to "a new generation of wheat varieties with higher yields and improved sustainability to meet the demands of a growing world population in a changing environment."

Between 2000 and 2008, wheat production fell by 5.5 percent primarily because of climatic trends, and in five of the past 10 years, wheat production worldwide was not sufficient to meet demand, according to the IWGSC paper.

What's more, with the global population projected to exceed 9 billion by 2050, researchers, breeders and growers are facing the challenge of increasing wheat production by about 70 percent to meet future demands, it said.

"A rapid paradigm shift in science-based advances in wheat genetics and breeding, comparable to the first green revolution of the 1960s, will be essential to meet these challenges," the paper said.

Wheat is one of the world's "big three" crops, along with rice and corn. The genomes of the latter two were published in 2002 and 2009, respectively.

A second paper in Science detailed the first reference sequence of chromosome 3B, the largest chromosome in bread wheat.

"The wheat genome only has 21 chromosomes, but each chromosome is very big and therefore quite complicated," said Eduard Akhunov, associate professor of the Kansas State University and a collaborator with the IWGSC.

"The largest chromosome, 3B, has nearly 800 million letters in its genetic code. This is nearly three times more information than is in the entire rice genome. So trying to sequence this chromosome -- and this genome -- end-to-end is an extremely complicated task."

The researchers described the findings as "a major landmark" towards obtaining a complete reference sequence of the bread wheat genome, a goal they said could be achieved within three years.

"With the draft gene sequence for each of the bread wheat chromosome and the first reference sequence of chromosome 3B, we have reached a great milestone in our roadmap," said Catherine Feuillet, IWGSC co-chair.

"We know now the way forward to obtain a reference sequence for the 20 remaining chromosomes and we hopefully will be able to find the resources to achieve this in the next three years."