Wheat remains worldwide staple

A clearer picture of how wheat has been able to adapt to such a wide range of climates and become one of the world's staple food grains has been pieced together by a team of researchers at the University of California, Davis. They accomplished this by isolating and cloning the VRN2 gene in wheat, which controls vernalization--the cold-weather requirement for triggering flowering. The findings of the study have practical implications for improving wheat varieties through manipulation of flowering times.

The researchers, who in 2003 cloned the first wheat vernalization gene, VRN1, discovered that VRN1 and VRN2 work together to confer the winter growth habit. They showed that loss-of-function mutations in either of these two genes result in spring wheat varieties that do not require cold weather to initiate flowering. These can be planted in spring to grow throughout the warmer months of the year. On the contrary, winter wheat germinates and goes through early stages in the fall but waits until the very cold winter weather passes before flowering in spring.

"During the 10,000 years of domestication of wheat, different mutations occurred in these two genes," indicates professor Jorge Dubcovsky, a wheat breeder and leader of the research group. "It is now possible to characterize these different mutations and study their effects on the adaptability of wheat to the different environments.

"These studies will provide breeders with a tool to select the best vernalization gene combinations for particular regions. An additional application of this discovery will be the experimental manipulation of cereals' flowering time. And a delay in flowering time could also be of particular value for forage grasses."

Working in collaboration with a team of researchers from the Department of Agriculture, Dubcovsky's group has produced a transgenic winter wheat that flowers 42 days earlier than the nontransgenic line. It is estimated by the Food and Agriculture Organization of the United Nations that the crop currently provides 23% of the food available for daily human consumption around the world.

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