In an upcoming issue of the Proceedings of the National Academy of Sciences, Randall Wisser, assistant professor in the Department of Plant and Soil Sciences, and colleagues published their finding that some genes in the maize (corn) genome can help protect the plant from multiple invaders. Their study focused on three fungal diseases, Southern leaf blight, Gray leaf spot, and Northern leaf blight, that threaten maize production worldwide and for which major epidemics have occurred in the U.S. and abroad.
“In many production environments growers are not contending with a single disease, they are battling multiple diseases and seek a sustainable means of doing so,” Wisser explained. “For instance, in Delaware we are now seeing both Gray leaf spot and Northern leaf blight co-occurring.”
To figure out if there might be a common genetic basis for resistance to the three diseases, researchers from the University of Delaware, Cornell University, Kansas State University and the United States Department of Agriculture at North Carolina State University collaborated to screen a large collection of diverse maize varieties for five years at different testing sites in the U.S. and developed new techniques to analyze their data.
The lengthy experiments paid off, providing unique insight into the genetics of plant disease resistance and cluing the researchers into at least one way in which plants can defend themselves against different enemies.
The authors arrived at their finding by developing a new method for examining multiple characteristics at once. The method is widely applicable and was developed in the framework of association mapping, an increasingly popular approach used to identify genes’ underlying characteristics ranging from plant productivity to human disease.
“Typically, different characteristics are analyzed individually which does not provide information on how they might be connected,” Wisser said. “To address our question, we needed a different way to look at our data.”
There are some examples for which the same gene is known to control multiple characteristics. The striking appearance of people with red hair and fair skin is partly determined by the same gene, which also causes sensitivity to UV radiation. Wisser and his colleagues set out to address the question of whether, like hair, skin and UV sensitivity in humans, specific genes could affect resistance to multiple diseases in maize.
They reasoned that if different pathogens used the same strategies to attack plants, then plants were likely to have developed a common mechanism to prevent their attack. By combining conventional field experimentation with contemporary genetics and statistical tools, the authors uncovered a detoxification mechanism that explained one way in which plants might defend themselves against the three diseases.
Funding for the research was provided by the Consultative Group on International Agricultural Research (CGIAR) Generation Challenge Program, North Carolina Corn Growers Association, US National Science Foundation, USDA-National Institute of Food and Agriculture, and USDA-Agricultural Research Service.