DNA sequence released by U.K. team still requires assembly

By Rachel Ehrenberg

Web edition: August 31, 2010

U.K. scientists made a big splash on August 27 with the announcement that they had unveiled the sequence of DNA in the wheat genome. “Wheat genome may help tackle food shortages,” headlines declared. And “Scientists crack through wheat's genetic code.”  

More like, “Scientists take a first crack at the genetic code of wheat.” Because what these scientists did is not comparable to what scientists have usually done when they announce that they have sequenced an organism’s genome.

Basically, the research team took wheat’s enormous genome — with 17 billion base pairs or “letters” of code, it’s about five times the size of the human genome — and chewed it into digestible chunks of 300 to 500 base pairs each. Then they figured out the string of code in each of those chunks. But they haven’t figured what order all those little pieces go in, a step that’s crucial for linking genes to traits that are important for improving wheat varieties.

By Monday, the International Wheat Genome Sequence Consortium, a more than 200-member organization of growers, breeders and scientists not affiliated with the U.K. project, took steps to sort the wheat from the chaff. In a press release, the consortium pointed out that “the raw sequence reads produced by the U.K. team could be viewed as similar to having an unordered string of all of the letters from a set of encyclopedia volumes.”  While the consortium appreciates that the team released the data to the research community, they also express concern that the hyped up press coverage is premature and could even jeopardize efforts to get a proper wheat sequence within the next five years.

What happened? The Biotechnology and Biological Sciences Research Council, which funded the project, did use the plural sequences in their press release, but such nuance is overshadowed by the rest of the release, such as the comment from the U.K.’s top science brass, Universities and Science Minister David Willetts: “This is an outstanding world class contribution by the U.K. to the global effort to completely map the wheat genome. By using gene sequencing technology developed in the U.K. we now have the capability to improve the crops of the future by simply accelerating the natural breeding process to select varieties that can thrive in challenging conditions.”

More cautious stories are now appearing. A big hint that this wasn’t your everyday, white-bread sequencing announcement (it still sent this reporter scrambling), was the research wasn’t published in a scientific journal. That’s standard operating procedure for sequencing feats and glories. When I spoke to the University of Liverpool’s Neil Hall, a member of the research team, he said they are hoping to publish within the year, but in the meantime wanted to put the data out there. Their immediate focus is repeating this first step with four more varieties of wheat.