For half a century, scientists knew that certain wheat plants could resist Hessian fly attacks. They just could not figure out exactly how. Now, for the first time, researchers have cloned the gene responsible and shown precisely how it interacts with the insect.
The work was done by researchers at the University of Maryland and their collaborators, and was published August 14, 2026, in the journal Science Advances. According to Phys.org, the study breaks through a barrier that has blocked progress in wheat pest resistance research for decades.
"This is very exciting for us, because it is the first time anyone has been able to clone pest resistance genes in wheat and demonstrate the direct interaction between the gene and the specific insect pest protein it reacts with," said Nidhi Rawat, an associate professor of plant science at UMD and a co-author of the paper.
Hessian flies are small, mosquito-like insects that cause hundreds of millions of dollars in damage each year to cereal crops including wheat, barley, and rye. In the United States alone, they account for roughly a 5% reduction in wheat yield annually. Unlike many crop pests, Hessian fly larvae do not simply eat the plant. Instead, they secrete chemicals through their saliva into plant cells, triggering the cells to transform into abnormal growths that feed the larva while draining the plant of nutrients.
Wheat has several genes that help defend against this chemical attack, but scientists had spent 50 years unable to demonstrate how those genes interact with the larval saliva proteins and trigger an immune response. Part of the difficulty is the wheat genome itself, which is large and complex with many repeated DNA sequences, making it extremely difficult to isolate individual genes.
Rawat and her colleagues developed new genomic tools to pinpoint the location of a resistance gene called H13. They then successfully grew wheat cultures in the laboratory with elevated expression of the gene.
The mechanism they uncovered is precise. When H13 detects a specific protein in the larval saliva, it signals nearby cells to die off while surrounding cells reinforce their walls, making them harder for the larva to penetrate. H13 also triggers the wheat cells to produce molecules that are toxic to the larvae. Together, these responses cut off the larva's access to nutrients, effectively starving and poisoning it.
After creating wheat cultures with high H13 expression, the research team was able to directly observe H13 being activated by the specific larval saliva protein, confirming the molecular mechanism that allows wheat to resist Hessian fly attacks. The research opens a path toward engineering more resistant wheat varieties using a defense system that the plant already carries.