Genes Hold Secret to Wheat's Success, Researchers Say
July 2, 2007
The success of wheat as a food crop can be traced through thousands of years of genetic changes that occurred as wheat was domesticated for human use, write UC Davis plant scientists Jorge Dubcovsky and Jan Dvorak in the cover article of the current issue of the journal Science.
In this review article of the molecular genetics and genomics of wheat, the authors paint the picture of how gene mutations and the presence of multiple chromosomes -- a characteristic known as "polyploidy" -- enabled modern wheat to overcome several genetic bottlenecks that occurred during wheat domestication and subsequent evolution.
The authors conclude that, "Polyploid wheat has been able to compensate for diversity bottlenecks by capturing a relatively large proportion of the variability present in wild wheat. In addition, new variation is rapidly generated in the dynamic wheat genomes through gene deletions and insertions of repetitive elements into coding and regulatory gene regions."
Domestication of wheat began roughly 10,000 years ago as people in western Asia began the transition from hunting and gathering to raising crops and animals. Some of the important traits that were selected for during the domestication process include increased grain size, changes in the toughness of chaff so that the wheat can be easily threshed, and retention of the grain on the plant so that it doesn't scatter in the wind before or during harvest.
Globally, approximately 620 million tons of wheat are now produced each year, providing one-fifth of the calories consumed by people around the world. Ninety-five percent of the wheat crop goes into making baked goods such as bread, cookies and pastries, while the remaining 5 percent is durum wheat used for making pasta and related products.
Funding for this study was provided by grants from the National Research Institute, U.S. Department of Agriculture and the National Science Foundation.
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