MANHATTAN, KANSAS, U.S. — A gene has been identified in order to identify new wheat varieties that will resist Fusarium head blight (FHB), a fungal disease that threatens production worldwide.
The 20-year-old study found a gene, known as TaHRC, plays a key role in providing resistance to FHB, also known as scab disease.
According to the U.S. Department of Agriculture’s (USDA) Agricultural Research Service (ARS), FHB thrives in warm and moist conditions and is becoming an increasing threat worldwide because of the unpredictable weather patterns brought on by climate change and an increasing trend toward more corn production and no-till farming, which both increase the availability of the pathogen in fields. The disease has caused an estimated $2.7 billion in losses in Minnesota alone since the 1990s, and forced many wheat and barley farmers there into bankruptcy. Growers often use fungicides to control it.
Guihua Bai, a plant molecular geneticist with the ARS in Manhattan, Kansas, U.S., and an adjunct professor in the Department of Agronomy at Kansas State University (KSU), said the research team was able to modify the production of select proteins in wheat by shutting off the gene, thus increasing the plants’ ability to resist FHB.
“Usually, it is just the opposite,” Bai said. “The loss of gene function usually makes plants susceptible (to a given disease). We found that this gene is a susceptible gene in most wheat lines and that deleting part of the gene caused it to lose its function, and thus make the plant more resistant.”
KSU said from 1993 to 2001 the disease caused $7.6 billion in losses in U.S. wheat fields, and more recently — in 2015 — the Kansas wheat crop was hit by an estimated 3.4% yield loss due to FHB.
“This disease will increase in frequency if weather conditions are wet and warm during the flowering stage,” Bai said. “We also know that the pathogen will grow in corn debris. The possibility of FHB increases in areas where corn is grown in a no-till situation where debris is left on the surface of soil.”
In addition to causing substantial production losses, FHB can cause a mycotoxin called deoxynivalenol that can cause sickness in humans and animals when healthy wheat mixes with infected seeds, Bai said.
KSU scientists think the TaHRC gene, previously called Fhb1, will provide the best resistance to FHB. It initially was found in a Chinese line and was introduced to U.S. wheat breeding programs more than 30 years ago.
“However, it had never been incorporated into U.S. hard winter wheat varieties through conventional breeding due to poor adaptation from its original Chinese parents,” Bai said. “In the past decade, our lab successfully moved the gene into 16 U.S. hard winter wheat cultivars from breeding programs in the Great Plains, including several cultivars from Kansas. These improved lines with the gene are being used as parents in Great Plains breeding programs, so this gene will be in hard winter wheat varieties in the next few years.”
Incorporating resistance by directly shutting off the TaHRC gene will take additional time, Bai said, but that process already has started. The natural variant of TaHRC is available in the Chinese line already being used for resistance.
“We developed a diagnostic marker based on the gene sequence, and breeders can now accurately select the gene using the DNA marker,” Bai said. “That means breeders can easily incorporate the new resistance through traditional breeding with the aid of DNA marker technology.”
The research was conducted through a collaboration between KSU and the ARS. In addition to Bai, the authors of the study published in Nature Genetics include Paul St. Amand, a plant geneticist with the USDA-ARS; and a KSU team in the departments of agronomy and plant pathology that includes Zhenqi Su, Amy Bernardo, Bin Tian, Hui Chen, Harold Trick and several visiting scientists.