Pathogens that attack crops constantly change to evade host immunity – or disease resistance in plant parlance. Sometimes a single gene makes the difference between a resistant crop and a susceptible one. In those cases the gene typically blocks the pathogen for a while – until the microbe makes a change.
That’s where quantitative disease resistance enters; multiple genes work together to offer levels of disease resistance in a plant. If the pathogen evolves to overcome one of the genes there are backups.
Tiffany Jamann, an assistant professor in the University of Illinois-Department of Crop Sciences, and her colleagues recently received $1.5 million from the National Science Foundation to study quantitative disease resistance in corn.
“Plant diseases cause an estimated 13 percent loss of global crop yields annually, reducing incomes and food quality and safety,” Jamann said. “Quantitative disease resistance usually works against all variants of pathogens so it’s an effective disease-management tool. Our research will identify disease-resistance mechanisms for some of the most important diseases of corn.”
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Because multiple genes work together in quantitative disease resistance, it’s more difficult to find them all. But Jamann has experience with that. She and her colleagues identified genes for resistance to bacterial leaf streak disease. She’s also worked to uncover pathogen lifestyle for other corn diseases as well as resistance mechanisms in sorghum.
In the new study the researchers aim to understand quantitative resistance to multiple corn foliar diseases and seedling diseases by looking at the level of the gene to the whole plant. Jamann said she’s interested in exploring how plants defend against vascular infection or how they keep pathogens from entering the xylem, the plant’s water-transport system.
“For example bacterial leaf streak is typically thought of as a nonvascular pathogen; usually the bacteria don't enter the xylem,” she said. “But we have a few corn lines that allow bacteria in that way so we're trying to understand why that's the case.”
Researchers at North Carolina State University also are working on the research. They’ll examine resistance to seedling diseases and use gene editing to make corn more resistant to foliar diseases of corn.
“Beyond the work on quantitative disease resistance we’ll make genetic resources available to the broader corn-genetics community,” Jamann said. “The resources will be useful beyond just looking at disease resistance.”
The project also includes an education component. Project partner North Carolina State University will participate in and provide funds to continue and update a plant-breeding and genetics workshop for science teachers. It also will support an AgDiscovery Camp for high school students. Visit aces.illinois.edu for more information.
Lauren Quinn is a media-communications specialist for the University of Illinois-College of Agricultural, Consumer and Environmental Sciences. The Department of Crop Sciences is in that college. Visit aces.illinois.edu for more information.