Behind-the-scenes researchers work to improve wheat at OSUPublished: Friday, May 14, 2021 By: Journal Record Staff Source: The Journal Record
Helping farmers in Oklahoma and around the world grow wheat to flourish despite challenges that might range from stripe rust to greenbug infestation involves a sizable team of federal and state researchers and extension educators working in collaboration at Oklahoma State University.
Many are familiar to producers in the state, as they might offer them face-to-face advice on things from crop timing to drought management.
But some equally important members of the OSU team remain largely behind the scenes, working in greenhouses and labs to identify and improve wheat traits.
Xiangyang Xu is one. He’s a research geneticist who scours national and international gene banks for old varieties or wild wheat relatives that might be used to introduce new disease- or insect-resistant genes in regionally adapted, high-performing lines popular with producers. His work might typically take three or four generations of repeated “backcrossing” to achieve desired results. But it’s incredibly important, as new pests, pathogens and diseases are constantly evolving, along with environmental stress factors such as drought.
According to Kelly Chamberlain, a fellow geneticist who directs the lab in Stillwater, what distinguishes Xu’s approach from traditional plant breeding is the use of genetic screening with “molecular markers.” To create markers, Xu collects plant tissue samples and then extracts DNA and analyzes it using an automated machine roughly the size of a toaster oven. He then uses what he learns, along with field observations, to hopefully strengthen traits or introduce desirable new ones in existing lines.
“These new lines still have to prove themselves in the field, but the time it takes to get to that point is shortened by using genetic screening,” Chamberlin said. “That’s important to farmers, who are struggling every year to make a crop.”
Rust, a common fungal disease, is a prime example of a challenge faced by farmers in Oklahoma. Wheat varieties lose resistance to the pathogen over time as new genetic strains emerge. Xu’s ability to discover new genes for resistance, and combine them with existing ones, creates more lasting durability.
“One gene alone can afford improved resistance, but when ‘pyramided’ (or stacked) with other resistant genes, we can get to where there’s virtually no leaf rust occurring in the crop for years to come,” Chamberlin said.
Xu was born in a rural area of the Henan province of central China. He recalls that when he was a child, crop yields were so low people had trouble producing enough food to feed their families. That motivated him to attend the nearby agricultural university and become a wheat breeder, a job he held for the next 10 years.
He then spent a year as a visiting scholar at the International Maize and Wheat Improvement Center, headquartered in Mexico, where he learned about marker-assisted selection. Recognizing the value of this new technology, he decided to pursue further graduate work and chose Oklahoma State, which appealed to him as a top program with a reputation for continuously introducing new varieties.
That eventually led to his current position. In his seven years at OSU, he has identified five genes for resistance that have been widely shared within the wheat breeding community. He is currently working on a stripe rust project anticipated to soon yield additional insights.
“Dr. Xu is an outstanding scientist, one of the best in the world, and we are very fortunate to have him here in Oklahoma,” Chamberlin said.
Gaining ground with gene mapping
OSU chief wheat breeder Brett Carver evaluates 300,000 separate data points before releasing a new variety, an exhaustive and meticulous list that includes everything from the maturity pattern across a plant’s life cycle to height and kernel size to milling and baking properties.
Selecting for the rate at which the plant matures is one attribute alone that has a huge economic impact in the Southern Plains. Delaying maturity allows farmers to graze wheat longer before removing cattle and still produce a summer grain crop. According to agronomists, one extra week of grazing generates an additional $4 to $8 per acre.
Figuring out key genes that influence when flowering occurs has been no small task.
“A trait might seem to be linked to more than 100 DNA sequences in the genome, but not all of those sequences actually affect the trait,” Carver said. “Gene mapping helps us figure out what the relevant sequences are and where they occur in the genome.”
Another mostly behind-the-scenes researcher at OSU, Liuling Yan, has spent more than a decade working closely with Carver to pinpoint four genes responsible for flowering time in winter wheat. A research paper about the project was recently published in the international science journal Nature Communications.
For Yan, coming to OSU in 2006 enabled him to fulfill a dream of running his own lab. But his career began much earlier in his native China, where he initially studied plant physiology.
“While analyzing research data from the field, I was intrigued by the large genetically controlled variances in phenotype (or physical appearance) between the many different types of wheat,” he recalls. “I decided to pursue the many questions I had about it.”
He moved to Australia to study, first at Melbourne University and then Victoria University, before eventually coming to the U.S. as a postdoctoral fellow.
Internationally Yan is recognized for discovering that rust resistance is determined by a three-gene sequence, rather than a single gene, as was previously believed, an important finding now being deployed in breeding programs around the world. He takes equal satisfaction from having contributed to the release of 19 new varieties, earning industry and academic awards along the way.
“Dr. Yan could have worked with other crops that produced more grant funding opportunities, but he chose to devote his career to wheat, providing a tremendous benefit to our industry,” Carver said.
In the future, genetic screening will continue to help uncover new traits related to grain quality and nutrition, which could have broad public health benefits, Carver added.
“That’s the kind of exciting innovation we want to be part of,” he said. “It’s not just about increasing yield. It’s about food; it’s about something that goes on somebody’s dinner table. That’s the total package we are breeding for here at OSU.”