科学美国人60秒:Give Us This Day the Bread Wheat Genome

Wheat helped create civilization in the Middle East. It’s a staple crop for 30 percent of the world’s population. And now, with the publication of four articles in the journal Science, we’re close to a detailed understanding of the bread wheat genome. [Kellye Eversole et al, Slicing the wheat genome]

Wheat is tough to sequence. It’s gone through multiple hybridizations, making its genome five times larger than a human one. Plus there are many redundancies: more than 80 percent of the genome is made of repeated DNA sequences. So the typical whole-genome shotgun approach—breaking genomes into segments and then reassembling them—doesn’t work for wheat.

Instead, an international consortium devised another strategy, involving physically mapping individual chromosomes and chromosome arms.

One paper details a draft of the entire genome of bread wheat. Another identifies all the genes on the largest of the plant’s 21 chromosomes. Some 75,000 genes have been mapped. The methods in the second paper will help scientists map the remaining chromosomes. They say it should take another three years.

Knowing exactly which genes are responsible for talents such as tolerating drought or improving yields should allow researchers to mine the genome and to quickly produce new and better wheat varieties to bring us our daily bread.

—Cynthia Graber