California Ag Network

Tag: genetics

  • Gene Discovery May Halt Worldwide Wheat Epidemic

    Davis, Calif., (November 20, 2017) – University of California, Davis, researchers have identified a gene that enables resistance to a new devastating strain of stem rust, a fungal disease that is hampering wheat production throughout Africa and Asia and threatening food security worldwide.

    The discovery by UC Davis wheat geneticist Jorge Dubcovsky and his team will help breeders more quickly develop varieties that can fend off the deadly pathogens and halt a worldwide wheat epidemic. The findings were recently published in the journal Proceedings of the National Academy of Sciences.

    Wheat and stem rust have been in an evolutionary arms race for more than 10,000 years. In the 1950s, a major epidemic of the disease spread through North America and destroyed up to 40 percent of the wheat crop, the world’s second most important grain next to rice.

    Since then, scientists have developed rust-resistant varieties to boost wheat’s immunity to stem rust. But the pathogens are making a comeback. A new strain of the stem rust — called Ug99 after it was discovered in Uganda in 1999 — is spreading throughout the region. About 90 percent of the wheat varieties grown worldwide are susceptible to Ug99.

    “Ug99 has expanded to most of the wheat-growing regions in Africa and has crossed the Red Sea to Yemen and Iran,” said Dubcovsky, a professor with the UC Davis Department of Plant Sciences and a Howard Hughes Medical Institute investigator. “Ug99 is now at the door of the Punjab region — the bread basket of Asia — and identification and deployment of effective resistance genes are critical to mitigate this threat.”

    Dubcovsky and his team identified three different resistance forms of Sr13, a gene from pasta wheat that is effective against Ug99 and another group of virulent stem-rust strains from Yemen and Ethiopia. In 2013, Dubcovsky and fellow researchers discovered another gene called Sr35 that also provides resistance to Ug99. The team is close to identifying a third gene that confers protection from the virulent strain.

    Why genetics matter – To develop better varieties, breeders cross plants with desired traits and select the best offspring over multiple generations. Once stem-rust resistant genes have been identified, breeders can use molecular markers (specific regions of DNA) to select for the genes at the seed or seedling stage. This accelerates the crop-improvement process.

    These molecular markers allow breeders to pyramid multiple stem-rust-resistant genes in the same plant to extend the durability of resistance.

    “Wheat provides a substantial amount of calories and proteins consumed by humans,” Dubcovsky said. “We hope that a better understanding of the wheat-rust pathosystem will speed the development of new strategies to control this devastating pathogen.”

  • Genome of Wheat Ancestor Sequenced

    Davis, Calif., (November 17, 2017) – Sequencing the bread wheat genome has long been considered an almost insurmountable task, due to its enormous size and complexity. Yet it is vitally important for the global food supply, providing more than 20 percent of the calories and 23 percent of the protein consumed by humans.

    Now, an international team of scientists led by researchers at the University of California, Davis, has come a step closer to solving the puzzle by sequencing the genome of a wild ancestor of bread wheat known as Aegilops tauschii, a type of goatgrass.

    In the study, published Nov. 15 in the journal Nature, researchers applied a combination of advanced technologies to generate a reference-quality genome sequence for Ae. tauschii, which is highly adaptable and tolerant of diseases. It is also the primary source of genes for the bread-making properties of wheat flour.

    The findings will allow researchers to discover new genes that can improve wheat baking quality, resistance to diseases, and tolerance to extreme environmental conditions like frost, drought and salinity.

    The effort has already had one practical result: the discovery of two new genes for resistance to a race of wheat stem rust to which there is virtually no resistance in wheat. The genes were transferred from Ae. tauschii into wheat and are now available to wheat breeders.

    Piecing together the puzzle

    Wheat and its wild ancestors have genomes much larger than humans, which makes sequencing difficult.

    “When we started this project nearly two decades ago, there was no technology to sequence genomes of that size and complexity,” said Jan Dvorak, a leader of the project and professor in the Department of Plant Sciences at UC Davis. “This group of plants are unique because their genomes are just absolutely full of repeated sequences. We found more than 84 percent of the Ae. tauschii genome consists of closely related repeated sequences.”

    Dvorak describes the project as like tearing up pages of a thick book and trying to piece it back together. “Only imagine that every sentence on the page is nearly identical. That was our task,” said Dvorak.

    The technologies used by the researchers can be applied to any plant genome, so the implications extend beyond wheat.

    Contributors to the research include scientists from USDA-ARS, Albany, California; John Hopkins University, Maryland; University of Georgia, Athens in the U.S.; and from Germany, Canada, China, U.K., France, and Switzerland. The research was funded with a grant from the National Science Foundation.

  • Dairy Producer Considerations for Genomic Testing

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    Genomic Testing was a big topic of discussion at the World Ag Expo dairy seminars this year. Genomic Testing is a new technology that is becoming more available and affordable to dairy producers; however, there are still many questions as to how it all fits in to individual dairy operations. Watch this brief video interview with Genetic Programs Manager at CRV, Sophie Eaglen, as she addresses several key points for dairy producers considering taking advantage of this technology. Read the full story in the March issue of California Dairy Magazine Digital.

     

  • Gene Editing Can Complement Traditional Food-Animal Improvements

    Thanks to gene editing, this calf pictured with Van Eenennaam will not grow horns and will not have to go through the dehorning process. (Karin Higgins/UC Davis)

    By Pat Bailey

    Quick Summary

    • Gene editing builds on traditional breeding successes
    • The technology enhances sustainability plus animal health and welfare
    • Questions remain about regulatory issues
     Gene editing— one of the newest and most promising tools of biotechnology — enables animal breeders to make beneficial genetic changes, without bringing along unwanted genetic changes.

    And, following in the footsteps of traditional breeding, gene editing has tremendous potential to boost the sustainability of livestock production, while also enhancing food-animal health and welfare, argues UC Davis animal scientist Alison Van Eenennaam.

    She examines the potential benefits of genome editing today, Feb. 17, at the annual meeting of the American Association for the Advancement of Science, held in Boston’s Hynes Convention Center. Her presentation is part of a session titled “The Potential of Gene Editing to Revolutionize Agriculture,” moderated by acclaimed molecular biologist Nina Federoff.

    Van Eenennaam also will participate in a news briefing on this topic at noon EST on Saturday, Feb. 18, in Room 103 of the convention center.

    Lessons from the dairy industry

    Thanks to improvements made in the dairy industry through traditional breeding, a glass of milk today is associated with just one-third of the greenhouse gas emissions linked to producing a glass of milk in the 1940s, says Van Eenennaam, a UC Cooperative Extension biotechnology specialist in the UC Davis Department of Animal Science.

    That was accomplished as traditional selective breeding improved the productivity of dairy cows so much that the number of dairy cows in the United States dropped from a high of 25.6 million in 1944 to about 9 million today, even as the country experienced a 1.6-fold increase in total milk production, she says.

    Potential of gene editing for food animals

    “A number of breeding methods, including artificial insemination, embryo transfer, crossbreeding and, more recently, genomic selection, have been used to achieve these improvements,” Van Eenennaam says. “Now, genome editing promises to complement traditional breeding programs by precisely introducing desirable genetic variations into livestock breeding programs.”

    She notes that genome editing has already been used to prevent livestock disease, including making pigs resistant to porcine reproductive and respiratory virus, and to improve animal welfare by developing dairy cows that don’t require horn removal.

    Additionally, research is underway to extend applications of gene editing in the future.  Gene editing might, for example, make it possible to produce offspring of only one gender, such as only hens for egg-laying operations.

    Regulatory process key for gene-edited food animals

    The potential for applying gene-editing techniques to make improvements in food-animal production largely hinges on future regulatory processes, according to Van Eenennaam.

    “It’s not yet clear what regulatory status food-animals produced with gene editing will have,” Van Eenennaam says, noting that gene editing does not transfer novel DNA into an animal, but can be used to make changes within the animal’s own genes.

    “The resulting DNA sequence may be identical to existing, naturally occurring DNA sequences,” she says. “The prospect that gene-edited animals would be subject to the same type of regulations that apply to an animal drug — even though their genetic modifications might be indistinguishable from those obtained through conventional breeding — is a concern for animal breeders who are eager to employ genome editing to complement traditional genetic improvement programs.”

    Media contacts

    Alison Van Eenennaam, UC Davis Dept. of Animal Science, 530-902-0875, alvaneenennaam@ucdavis.edu

    Pat Bailey, UC Davis News and Media Relations, 530-219-9640, pjbailey@ucdavis.edu

  • New $9.7 Million Grant Funds Search for Wheat Yield Genes

    Featured Image Credit: (Karin Higgins/UC Davis photo)

    – Increasing wheat yield rapidly enough to meet population growth has been a challenge for wheat breeders. An international research project, headed by plant geneticist Jorge Dubcovsky, professor in the Department of Plant Sciences at UC Davis, is using new technology to identify the wheat genes that impact yield.

    “Grain yield is one of the most difficult traits to address in wheat,” said Dubcovsky. “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.” (Tillers are segmented stems found in wheat and other grasses.)

    The importance of wheat – In contrast to crops like maize and soybean, 65 percent of the wheat varieties in the U.S. come from the public sector (in contrast to private-sector plant-breeding companies). The wheat industry in the U.S. therefore relies on public-sector wheat breeders to develop improved wheat varieties.

    Wheat is different from other cereals, in that it has a higher protein content than rice or maize, so it’s important for humans. More than 700 million tons of wheat is produced worldwide each year, and 20 percent of the global caloric and protein intake comes from wheat.

    Public-sector wheat breeders in the U.S. have worked together for many years with the support of USDA Coordinated Agricultural Projects (CAP) to characterize agronomically important traits such as disease resistance and quality, but significantly increasing wheat yield has been an elusive goal. This year the Wheat CAP project is joining forces with the International Wheat Yield Partnership (IWYP), a consortium coordinating efforts across the world to accelerate improvements in wheat yield.

    Research support from NIFA – A new five-year $9.7 million grant, from the U.S. Dept. of Agriculture’s National Institute of Food and Agriculture (NIFA), will continue to support the coordination of public wheat-breeding programs in the U.S. The research focus is 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. A wheat yield increase of about 1 percent per year, typical up until now, will not meet the needs of a fast-growing human population.

    According to Dubcovsky, “This new project will allow us to understand the genes that control the different yield components, along with total yield.”

    It sounds straightforward, but it’s 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.

    Sequencing most wheat genes – In collaboration with a group in the UK, Dubcovsky’s group previously developed a tool called “exome-capture” (or gene capture) that can 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.

    Dubcovsky’s lab is working to increase the number of grains in the wheat spike, while other groups in the WheatCAP team and IWYP are focusing on increasing grain size.

    Researchers are already testing a gene that increases grain size by 7 percent in wheat varieties grown in California and the UK. It is not yet clear, however, whether the increased grain size will result in an increase in total yield. As part of this project, breeders will move the large-grain trait into varieties known to have the potential for producing high biomass and high yield.

    The need for future plant breeders

    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 generations of breeders that are critical for our future food security.”

  • Taking Advantage of Genomic Testing on Dairies

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    At the World Ag Expo, Dairy Producers gathered to learn about how to improve their dairy operations, and Lindsey Worden shared that the key is in genetics. Genomic testing is a great place to start, and she shared how to go about doing that. Watch the video and learn more at CaliforniaDairyMagazine.com.