Researchers Targeting Drought-Tolerance Traits In Crops

Key takeaways

• Colorado State University is studying and developing wheat, corn and sorghum to withstand drought.
• Over 63 years of wheat breeding, CSU has developed varieties that are remarkably productive in the state’s dry climate, as well as varieties that are pest and weed resistant.
• CSU scientists decipher the plant's genetic code and do field testing to determine which genes correspond with desirable traits that make a plant better adapted to drought.

Drought is a persistent issue for agriculture in Colorado and the U.S. West – one that has been exacerbated this year by a record-low snowpack. It’s no surprise, then, that Colorado State University continually works to identify and develop drought tolerance in crops to ensure farmers can remain competitive and provide food for people and livestock.

CSU wheat varieties occupy 85% of the wheat acreage in the state, thanks to close collaboration with Colorado wheat farmers. With support from the Gates Foundation, CSU sorghum research is making a real difference in food security in a part of the world that needs it most. And by studying the genetic foundation of crop traits, CSU researchers are making discoveries that contribute to understanding all life on the planet.

SOURCE spoke with researchers about a few of the crops CSU is studying and developing to withstand drought: wheat, Colorado’s top crop by acreage; corn, Colorado’s top cash crop; and sorghum, a staple consumed by 500 million people globally – and a promising option for dryland farming on the High Plains.

Successful collaboration
CSU’s wheat breeding program works closely with farmers to develop unique varieties of wheat adapted to Colorado’s harsh growing conditions.

“We test on 16 farms, so we’re experiencing what the farmers are experiencing, and drought is the number one issue impacting Colorado wheat farmers,” said Professor Esten Mason, project leader of CSU’s Wheat Breeding and Genetics Program.

Over 63 years of wheat breeding, CSU has developed varieties that are remarkably productive in the state’s dry climate, as well as varieties that are pest and weed resistant.

“At one time, producing 30 bushels per acre yield in the best conditions was hard to achieve,” Mason said. “Now our varieties can produce 30 bushels with just a couple of inches of precipitation in a season.”

At the Eastern Colorado Research Center in Akron recently, Mason stood among wheat trial plots and explained what a tough year this has been for wheat. Pests and disease have both been bad, but all this year’s issues started with drought, he said. Most test sites he monitors did not receive any measurable precipitation for about eight months.

“Drought set us back so much that when the rains came, it was too late,” Mason said. “A stressed plant can only hold out so long to everything else that’s trying to attack it.”

The program has solid partnerships with farmers around the state, who allow CSU to plant test plots on their land and harvest the grain. Farmers manage the field as they normally would, and most of the grain is added to their yield after the researchers take the small amount they need for research.

“I think the strength of the program is our consistency,” Mason said. “We put out new varieties every year, and it gives farmers a consistent supply of new genetics that they can try and see what works for them.”

Alan Linnebur and his brothers grow primarily dryland wheat east of Denver, and they have planted CSU varieties to help with issues from wheat stem sawfly to weeds. Linnebur, who is a CSU alum and a customer focus group co-chair with the U.S. Department of Agriculture Agricultural Research Service station in Akron, said research is continually needed to keep pace with the constantly evolving challenges in complex biological systems. He joked that Mason has job security because wheat diseases are evolving along with the solutions.

“It’s remarkable the work that’s done, and we’ve benefitted a great deal from those new varieties that have been developed as a result of a lot of hard work,” Linnebur said.

Getting to the root of drought tolerance in corn
Corn is the top commodity crop in the United States, with 90 million acres grown a year, according to the USDA. There’s a huge global market for corn, which is primarily used for livestock feed and ethanol, but it’s a thirsty crop that requires irrigation to grow in Colorado. That’s not going to change any time soon, but CSU researchers are working to identify the genetic basis for drought tolerance in corn – valuable knowledge because drought is the biggest threat to yields.

John McKay, a professor of soil and crop sciences, studies the genetic variation that makes some plants better adapted to drought than others. In research funded by the National Science Foundation and U.S. Department of Energy, he has identified genes that make certain corn varieties less sensitive to limited soil moisture.

His team plants hundreds of different genetic variants at CSU’s Agricultural Research, Development and Education Center every year. Corn is grown as it would be by Colorado farmers, except the researchers manipulate water availability by limiting irrigation for some plots while fully irrigating others, and they sample the roots throughout the growing season.

As with all plant species, corn roots are complex structures influenced by both genetics and the environment where they are grown. Environmental conditions change the way plants react to their genetic instructions, and this interplay of nature and nurture represents a fundamental research question that applies to all species.

“We’re looking at how the roots are changing the expression of different genes in the genome to adjust their growth and physiology and perform better under drought,” McKay said.

McKay uses advanced technology and classic, highly replicated experiments to uncover which genes correspond with desirable traits, such as root depth, that make the plant better adapted to drought. His lab then works with seed companies and the International Maize and Wheat Improvement Center to incorporate desirable traits into new hybrid corn varieties that can be grown all over the world.

“We ultimately want to find genes that affect traits that would matter in the field,” McKay said, adding that the value of this research extends beyond a single crop and addresses basic as well as applied questions.

“Research like this to understand how variation in genomes affects traits and how organisms develop and respond to the environment is knowledge that’s useful for natural systems, for artificial-selection systems like crops and livestock, and for human health.”

Genetic scavenger hunt
Sorghum is a nutritious food for people and livestock and a good source of bioenergy. In the U.S., sorghum is grown on a relatively small scale, but because it is naturally adapted to dryland systems, it has the potential to benefit farmers in the western Great Plains who have relied on the diminishing Ogallala Aquifer for thirstier crops like corn.

Geoff Morris, a professor of soil and crop sciences, leads a research program that works with farmer groups and breeders around the world to enhance sorghum for nutrition and drought and pest resistance. His research over the past decade has improved crop resilience for farmers in the U.S. and beyond.

Morris’ lab uses computational approaches and greenhouse and field experiments to find the genes responsible for specific beneficial traits. After decoding the plant’s DNA, the researchers run growth-chamber experiments that precisely control the environment to see how the genes react to dry air, for example. Next, they test in the field or distribute the trait technology to others to confirm that results are replicable under real-world conditions.

The Morris lab used this process to decipher the genetics for stay-green and limited-transpiration traits that allow sorghum to remain productive despite drought stress. Ph.D. student Gina Cerimele likens the research to a genetic scavenger hunt.

“Our goal is to improve the livelihood of anyone who can benefit from sorghum as a crop, whether it’s their nutrition or their economic livelihood,” Cerimele said, adding that sorghum can keep farmland productive where it’s difficult to grow other crops.

Cerimele’s graduate work evaluating sorghum planted in Colorado and Kansas was supported in part by producer-led organizations. She said she is satisfied knowing her work is serving needs identified by farmers.

“We’re an applied program, so our goals are to serve stakeholders, and our stakeholders encompass not only the farmers and the breeding programs, but also the people who consume the products,” Cerimele said.