The first isolation of an Insect Pest Resistance gene could lead to more resilient varieties of wheat
Hessian Fly
Image Credit: USDA ARS
Researchers at the University of Maryland and their collaborators have cloned a gene that makes wheat resistant to predation by Hessian fly larvae and demonstrated its direct interaction with a protein produced by the insect. The research breaks through a longstanding barrier to understanding and engineering pest resistance in wheat. It is described in a research paper published on August 14, 2026 in the journal Science Advances.
“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 coauthor of the paper.
Hessian flies are tiny, mosquito-like insects that cause hundreds of millions of dollars in damage to cereal crops like wheat, barley, and rye around the world, and account for roughly 5% reduction in wheat yield in the US annually. Unlike other pests that eat crops outright, Hessian fly larvae secrete chemicals through their saliva into plant cells. These chemicals transform the cells into an abnormal growth that feeds the larva while robbing the plant of nutrients.
Wheat has several genes that help the plant defend against the chemicals in Hessian fly larva saliva, but in 50 years of trying, scientists had not been able to demonstrate how those genes interact with the proteins in larvae saliva and trigger an immune response. That means they have not been able to understand how resistance against Hessian flies works.
In order to observe the reactions of specific genes and proteins, scientists must isolate the target gene, often cloning it in another organism, like yeast or bacteria that rapidly multiplies and produces millions of identical copies of the gene. But the wheat genome is large and complex, with many repeated DNA sequences, which has made identifying and cloning individual resistance genes nearly impossible. Rawat and her colleagues developed new genomic tools to pinpoint the location of the Hessian fly resistance gene H13 and successfully grow wheat cultures with an over-expression of the gene in the laboratory.
When H13 detects a specific protein in larval saliva, the gene tells nearby cells to die off and surrounding cells to reinforce their walls, making them harder to penetrate. H13 also causes the wheat cells to produce molecules that are toxic to the larvae. This action cuts off access to the nutritious fluids and tissues in a plant, starving and poisoning the larvae.
After isolating the gene and creating H13 amped-up wheat cultures, Rawat and the research team were able to demonstrate the activation of H13 by a specific protein in the fly larva, validating the molecular mechanism that enables wheat to resist Hessian fly attacks.
Fifty years after the discovery of genetic resistance to Hessian fly, researchers can now begin to develop a gene-based solution for a persistent agricultural pest that affects wheat growers on a global scale.
Additional authors from the University of Maryland Department of Plant Science & Landscape Architecture include Associate Professor Vijay Tiwari.
This research was a collaboration with researchers at USDA-ARS, Purdue University, Kansas State University, Corteva Agriscience, Ohio University, Texas A&M University.
Support was provided for various parts of this research by USDA-CRIS Number 5020-1012 21000-001-000-D, USDA’s Agriculture and Food Research Initiative (AFRI), project award nos. 2010-03741 and 2019-67030-29670, USDA National Institute of Food and Agriculture (NIFA) award no. 2021-67013-33568.
