- Author: Diane Nelson
Led by Jorge Dubcovsky, professor in the Department of Plant Sciences at UC Davis and an international expert in wheat breeding and genomics, researchers are decoding the genetic clues that help public and private breeders worldwide develop wheat varieties that resist disease, tolerate drought, and provide even greater nutrition.
"Nobody else is doing the extensive wheat research they conduct at UC Davis," said Patrick Klinger, a grain distributor with both the international agribusiness firm Wilbur-Ellis and Blair Grain Company in Stockton. "If they weren't doing it, it wouldn't get done."
Klinger was one of the few hundred growers, breeders, seed distributors and others who attended a recent Small Grains Field Day at UCD where the latest developments in wheat and other grains were on display. They toured test plots west of campus where Dubcovsky and his team are growing various wheat plants, examining them to find material that can be used to breed better varieties.
Wheat is one of the most important crops worldwide, accounting for 20 percent of what humans eat every day. Making wheat more nutritious and adaptable to different environments has a big impact on feeding the world's growing population.
In California, wheat is a primary crop for many producers and a valuable rotation crop, helping manage disease and improve the condition of the soil. California growers produce about 1.1 million tons of wheat each year for human and animal consumption, with a total value of $337 million.
Dubcovsky's lab has forged new territory in wheat genetics — mapping, isolating, and cloning developmental genes from the plant's huge, unsequenced genome. In 2006, Dubcovsky discovered a way to boost protein, zinc and iron in cultivated wheat by bringing back from wild wheat a gene that move nitrogen and other nutrients faster and more efficiently from leaf to grain, ferrying additional nutrients into the seed before the plant dies. Almost all modern wheat varieties have a defective copy of this gene.
And that was just the beginning of his in-depth, molecular investigation into the plant's aging process. Dubcovsky's lab currently supports 13 graduate students helping investigate critical stages of wheat's development cycle, cloning genes involved in drought tolerance, spike development, and disease resistance.
"The more we understand about how genes modify theses processes, the better equipped we are to breed varieties that are matched to a changing climate, and even produce more grains per spike," Dubcovsky said.
During the recent tour, Dubcovsky's lab presented promising work with isolating genes resistant to stripe rust, a devastating wheat disease; genes that allow wheat to flower a few days early, thus saving precious irrigation water; genes that allow wheat to tolerate drought conditions; and genes that increase fiber-like resistant starch in wheat.
Resistant starch is resistant to digestion, and behaves as additional fiber. Resistant starch has powerful health benefits, including reduced rates of obesity, diabetes, heart disease and cancer.
"We're working to increase the percentage of resistant starch to other starch in wheat," said Brittany Howell, a doctoral student in Dubcovsky's lab. Through her breeding efforts, Howell has already increased resistant starch in wheat by 600 to 700 percent.
During his 18 years at UCD, Dubcovsky and his program have released eight wheat varieties, five others in collaboration with industry, and 30 germplasm, all designed to solve specific issues with environment, disease, yield and nutrition. A new variety of Hard Red Spring wheat, resistant to stripe rust, will likely be released next year. The stripe rust-resistant varieties are now being field tested by UC Cooperative Extension advisors.
All of Dubcovsky's research, varieties and genetic material are publically available for breeders and researchers around the world to expand upon and use.
"Yes, we like to share and collaborate," Dubcovsky said. "Better science makes better wheat. And better wheat reduces hunger and poverty, and improves people's lives around the world."
Dubcovsky is a 2014 winner of the Wolf Prize in Agriculture, awarded each year to the world's most outstanding scientists working in agriculture. He's a member of the National Academy of Sciences, and a Howard Hughes Medical Institute and Gordon and Betty Moore Foundation investigator.
- Posted By: Jeannette E. Warnert
- Written by: Diane Nelson, (530) 752-1969, email@example.com
The stripe rust disease of wheat caused by the highly specialized fungal pathogen Puccinia striiformis f. sp. tritici has been responsible for recurrent episodes of large yield losses and economic hardship among grain-based agricultural societies for centuries. Current epidemics of new aggressive races of Puccinia striiformis that appear after the year 2000 pose significant threats to food security worldwide and, in particular, in developing countries in Africa and central Asia. In spite of its economic importance, the Puccinia striiformis genomic sequence is not currently available.
In order to get access to the genes of this pathogen, a team of researchers – including Professor Jorge Dubcovsky (also a Howard Hughes Medical Institute researcher) and Professor Richard Michelmore, director of the UC Davis Genome Center, Project Scientist Dario Cantu and Manjula Govindarajulu, a postdoctoral researcher in Michelmore’s lab - used cutting-edge technology to rapidly sequence a large portion of the genome of one of the Puccinia striiformis more virulent and aggressive races. They assembled long stretches of the Puccinia striiformis genome and established a preliminary automatic annotation of its genes, with a special focus on those likely to be involved in pathogenicity.
This information is available in the open-access article published by the Public Library of Science and made publically available through the National Center of Biotechnology information and a dedicated web page.
“This shotgun sequence assembly does not substitute for the need of a complete and annotated Puccinia striiformis genome, but it provides immediate access to a large proportion, more than about 88 percent, of the genes from this pathogen,” said Cantu. “This public information has the potential to accelerate a new wave of studies to determine the mechanisms used by this pathogen to infect wheat, and hopefully to reduce current yield loses caused by this pathogen.”
These researchers, in collaboration with others at the John Innes Institute in the UK, are currently sequencing new and old races of Puccinia striiformis to investigate their differences in virulence and aggressiveness.
This project was supported in part by funds provided through a grant from the Bill & Melinda Gates Foundation, and the National Research Initiative Competitive Grants from the USDA National Institute of Food and Agriculture.