WASHINGTON, Nov. 30, 2016 - There’s some good news for wheat farmers around the globe. A research team led by Kansas State University scientists says they have isolated and cloned a gene that provides resistance to Fusarium head blight, or wheat scab, a crippling disease that caused $7.6 billion in losses in U.S. wheat fields between 1993 and 2001.
Bikram Gill, distinguished professor of plant pathology at KSU and the director of the school’s Wheat Genetics Resource Center, estimates that nearly 100 scientists, faculty, staff and students participated in the research. The journal Nature Genetics published the team’s findings online, noting that work on the project goes back about 20 years and includes contributions from China and several American universities.
"The breakthrough that we're reporting is the cloning of a resistance gene," Gill told K-State News in an interview. "We have identified the DNA and protein sequence, and we are getting some idea of how this gene provides resistance to the wheat plant for controlling the disease. The cloning of this gene is the key to unlock quicker progress for control of this disease."
Fusarium head blight is a disease that shows up periodically in more humid growing regions. It caused severe damage in Minnesota and North Dakota in 1993 and subsequent years. Gill noted that a 1997 epidemic in Minnesota, which ruined 50 percent of the state's wheat crop, caused an estimated $1 billion in losses.
Wheat scab is caused by the fungus Fusarium graminearum, which produces a toxin that makes the crop unfit for human and animal consumption. James Anderson, a professor of wheat breeding and genetics at the University of Minnesota, said there are frequent epidemics of the disease reported in the United States, Canada, Europe, Asia and South America.
The fungus is also a menace to the barley industry. Gill noted that since the 1997 outbreak in Minnesota, malting barley is rarely grown in the upper Midwest because the industry implemented zero tolerance for the toxin Deoxynivalenol produced by fusarium.
Previously, the wheat variety known to best resist Fusarium head blight was a Chinese cultivar named Sumai 3. But while scientists knew Sumai 3 provided resistance, they did not know what DNA sequence was responsible for resistance — until now.
Kansas State University faculty and students used sophisticated wheat genome sequencing techniques to isolate the gene. Gill said that Eduard Akhunov, associate professor of plant pathology, prepared a library of "millions of clones" of Sumai 3 DNA. Lead scientists Nidhi Rawat at the University of Maryland and Mike Pumphrey at Washington State University sifted through the library.
Rawat told Agri-Pulse that her efforts were just the “end of a very long chain,” and that researchers had been sifting through the library for years.
Gill said it was “like searching for the proverbial needle in the haystack” to find one clone that contained the resistance gene. "It looks like when the fungus attacks the wheat plant, the resistance gene protein has domains for binding and making pores in the cell wall of the fungus, and stopping it from spreading and infecting the developing grain," he said.
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