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, which have practical implications for improving wheat varieties through manipulation of flowering times, will be reported in the March 12 issue of the journal Science.
The researchers, who last year 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 don't require cold weather to initiate flowering. These varieties can be planted in spring to grow throughout the warmer months of the year. On the contrary, winter wheat varieties germinate and go through early growth stages in the fall but wait 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," said Professor Jorge Dubcovsky, a wheat breeder and leader of the UC Davis 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," he added. "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 U.S. Department of Agriculture's Western Regiona
Contact: Pat Bailey
University of California - Davis