Scientists have mapped out the genome for bread wheat, a feat researchers hope will eventually lead to a more drought-resilient and productive crop.

With a sequence of 17 billion base pairs, the Triticum aestivum, or bread wheat, genome is about five times larger than the human genome.

Two years ago, the researchers published raw sequencing data. That information was broken into smaller pieces and reassembled by matching overlapping ends of repeated genetic information. This longer sequence was then compared with similar grasses like rice and barley. The results were published in this week's Nature.

The reason for this complexity is that common bread wheat is actually three different ancestral grasses that have fused into one genome over thousands of years. About 80 percent of the genome data published two years ago was made of repetitive sequences, and much of the recent work was to determine which sequences were unique and which were repetitions.

The complexity allowed wheat's great geographical range, said Neil Hall, a professor at the University of Liverpool and one of the authors of the report.

"This is why it can grow everywhere from the Middle East to Northern Europe," Hall said. "It's an incredibly versatile grass."

A need to double output by 2050

Genetic advances are a top priority in order to increase grain yields in the face of climate change, a booming world population and shifting consumption patterns. In many countries in Africa, increasing wheat yields is an important goal as the population is expected to nearly quadruple in the next 40 years -- mostly in urban centers, where traditional cooking has given way to more convenient loaves of bread, crackers and other wheat products.

In addition, sub-Saharan Africa stands to be the region most vulnerable to climate change. There is a gap of 37 million metric tons between what Africans consume and what they produce in wheat, a discrepancy experts sought to resolve at a recent meeting in Addis Ababa, Ethiopia (ClimateWire, Oct. 9).

"At the moment, we've got to double output by 2050 to keep up with the world's population," Hall said. "It's an important challenge."

The genome is classified as a hexaploid, which means it carries six copies of each of its seven chromosomes. In contrast, the human genome is diploid, meaning it carries 23 pairs of chromosomes, a total of 46.

From this point, researchers will still need to decipher which genes are responsible for certain traits. The researchers will work toward uncovering the gene function and passing on the information to plant breeders.

"There's still a long way to go in fully deciphering the genome," Hall said. "This is a milestone in that process."

"It's still a draft," he was quick to add. "There's a lot of incremental processes."