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Draft of The Wheat Genome Completed

The International Wheat Genome Sequencing Consortium recently published a chromosome-based draft sequence of wheat's genetic code - its genome.

The genetic blueprint of bread wheat, also known as common wheat, is an invaluable resource to plant science researchers and breeders because it is grown on more than 531 million acres around the world and produces nearly 700 million tons of food each year, said Eduard Akhunov, associate professor of plant pathology at Kansas State University.

"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. This resource is invaluable for identifying those genes that control complex traits, such as yield, grain quality, disease, pest resistance and abiotic stress tolerance. They will be able to produce 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."Akhunov said

Although a draft, the sequence provides new insight into the plant's structure, organization, evolution and genetic complexity.

"This is a very significant advancement for wheat genetics and breeding community," Akhunov said. "The wheat genome sequence provides a foundation for studying genetic variation and understanding how changes in the genetic code can impact important agronomic traits. In our lab we use this sequence to create a catalog of single base changes in DNA sequence of a worldwide sample of wheat lines to get insights into the evolution and origin of wheat genetic diversity."

"The wheat genome only has 21 chromosomes, but each chromosome is very big and therefore quite complicated," Akhunov said. "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."

In order to analyze the vast amount of genetic information, researchers used a technique called shotgun sequencing. This divided the wheat genome into chromosomes and then split each chromosome into smaller segments. Chromosomal segments were analyzed by short gene sequences and overlapping sequences were stitched together with computer software.

The chromosome-based daft sequence the critical step before the full wheat genome is sequenced, Akhunov said. The sequencing approach developed for the 3B chromosome can now be applied for sequencing the remaining chromosomes in wheat. The consortium estimates the full genome sequence will be available in three years.

The research is funded by the U.S. Department of Agriculture's National Institute of Food and Agriculture.