February 9, 2009
The United States, the world’s
leading exporter of wheat, is struggling to keep pace with
demand, and a decline in grain available is causing a worldwide
crisis. Improving the performance of winter wheat is crucial to
keeping pace with worldwide demand.
With funding from USDA’s
Cooperative State Research, Education, and Extension Service
(CSREES), scientists in California have identified the genes in
wheat that are responsible for the plant’s tolerance to freezing
temperatures. This discovery may lead to improved crop
The tolerance for freezing temperatures varies in different
winter wheat varieties, ranging from 1 to 10 degrees Fahrenheit.
When temperatures fall below this range, wheat is either injured
or it dies. Reduced grain production presents serious economic
Wheat breeders have long recognized the need to produce
cultivars with greater resistance to freezing temperatures, but
have had limited success at developing cultivars that exhibit
improved freezing tolerance. This may be due in part to the
regulation of temperature tolerance by multiple genes as well as
the variable nature of freeze injury in fields where snow and
sloped ground create microclimates.
"It has been difficult for wheat breeders to develop more
winter-hardy varieties because frost tolerance in wheat is a
complex trait that is regulated by many genes," said Professor
Jorge Dubcovsky, a wheat breeder and geneticist.
Dubcovsky led an international team of scientists from the
University of California–Davis (UCD) and European institutions
to identify the genes that regulate temperature tolerance in
wheat and to identify frost-susceptible varieties.
The research team had previously identified a compact group of
11 genes on wheat chromosome 5AL. These genes play key roles in
regulating a large number of other genes that confer tolerance
to cold temperatures.
The team demonstrated that the frost-tolerant variety activated
two of these genes earlier than the frost-susceptible varieties
when exposed to decreasing temperatures. This earlier response
helped to better prepare the plants for freezing temperatures.
“This research has great potential to be directly incorporated
into winter wheat breeding programs where improved winter
survival is a goal,” said project collaborator Dr. Kim
Garland-Campbell. “The research to date has focused on
differences between spring habit, cold-sensitive wheat and
winter habit, winter-tolerant wheat. Our next step is to further
examine differences in freezing tolerance among winter wheat
varieties to determine which genes are present and active in the
hardiest varieties, such as from Russia, the Ukraine, Canada,
western Nebraska, and other locations with extremely severe
The project team will use these discoveries to screen wheat
varieties for the best combinations of frost tolerance genes and
then develop genetic markers to accelerate the selection of
hardier wheat cultivars.
"The identification of these optimum gene combinations will
enable breeders to develop hardier winter wheat, which is of
vital importance in light of growing pressures to increase
global food production," Dubcovsky said.
The United States annually produces more than 50 million metric
tons of wheat, which is used to make a broad spectrum of food
products ranging from breads to pastas. The results of this
research will enhance wheat sustainability and production.
This project is part of the CSREES National Research Initiative
(NRI) Plant Genome program and included participants from UCD,
USDA’s Agriculture Research Service, Washington State
University, the Ohio Plant Biotechnology Consortium, and the
Hungarian Academy of Sciences.
Through federal funding and leadership for research, education
and extension programs, CSREES focuses on investing in science
and solving critical issues affecting people’s daily lives and
the nation’s future. For more information, visit
By Stacy Kish