University of California
University of California-Davis plant geneticist Jorge Dubcovsky examines one of the wheat plants being raised in an indoor growth chamber.
Photo courtesy of Karin Higgins/UC Davis
DAVIS, CALIFORNIA, U.S.  — With funding from the U.S. Department of Agriculture’s (USDA) National Institute of Food and Agriculture (NIFA), researchers are attempting to identify and characterize the genes controlling wheat yield.

The international project led by researchers at the University of California, Davis, was one of seven projects seeking to develop new wheat varieties that received funding from NIFA in mid-December.

“Grain yield is one of the most difficult traits to address in wheat,” said Jorge Dubcovsky, plant geneticist at UC Davis, who is heading the research. “Fortunately, we now have more powerful tools, so we’re tackling this important trait even though it is difficult. We need to identify the genes that make the grains bigger, that increase the number of grains per spikelet, and that result in more-productive tillers.”

The $1.7 million grant announced in mid-December is part of a five-year $9.7 million grant that will focus on the identification of genes controlling grain yield and their utilization to improve wheat productivity through breeding research at UC Davis and partnering universities.

The wheat breeding program at UC Davis has long used traditional breeding combined with molecular markers to accelerate the deployment of other traits, but no molecular markers were available for yield. The new molecular markers for genes controlling yield traits will accelerate progress in this area.

It is extremely difficult to breed for yield components. Yield in wheat consists of the average weight of the grain, the number of grains produced per plant, and the number of spikes produced per unit of growing area — these all contribute to total grain yield.

In collaboration with a group in the U.K., Dubcovsky’s group previously developed a tool called “exome-capture” (or gene capture) that may be used to sequence most of the wheat genes at a low cost, while ignoring the repetitive part of the very large wheat genome.

“Using this new technology, we’ve had to sequence only 180 megabases, rather than the entire 16,000 megabases of the complete bread-wheat genome,” Dubcovsky said. The researchers used this tool to identify more than 10 million mutations in all the wheat genes.

At least 15 graduate students will be trained in this project at different universities. Each student will be in charge of the identification and deployment of one of the beneficial genes. This training is important because there is an increasing demand for modern plant breeders, and limited places to train them.

“With fewer active breeding programs in the universities, the wheat industry – breeding companies, growers, millers, bakers and the National Association of Wheat Growers – strongly supports this program because they desperately need people with technical skills to do the breeding,” Dubcovsky said. “Public breeding programs play an important role in training a new generation of breeders that are critical for our future food security.”