USDA grant to support study at Penn State on antimicrobial tolerance in plants

Pennsylvania State University

Kevin Hockett, assistant professor of microbial ecology in Penn State’s College of Agricultural Sciences, recently received a $682,500 grant from the U.S. Department of Agriculture’s National Institute of Food and Agriculture to study bacterial control methods and their implications for disease prevention in plants.

“We are grateful to the USDA for its recognition of our work, which has a goal of enhancing food security by preventing crop disease and food spoilage,” said the Lloyd Huck Early Career Professor, whose lab focuses on understanding how molecular interactions affect the ecology and evolution of plant-associated bacteria.

Hockett said the goal of the three-year project is to identify the extent, genetic mechanisms and potential agricultural consequences of bacterial tolerance to antimicrobials. He explained that certain antimicrobial agents, such as membrane-targeting proteins from plants and bacteria, have been proposed as a method to protect plants from destructive bacteria. These treatments inhibit or kill microbes to prevent yield loss and food spoilage.

“While plants also produce an array of their own antimicrobial peptides that kill microbes, we’ve discovered that bacteria can tolerate these membrane-active peptides, a phenomenon termed ‘persistence,'” he said.

Such persistence complicates the effectiveness of antimicrobial treatments. Previous studies, Hockett pointed out, have predicted for many antimicrobials, including those that are outer membrane-targeting, that persistence can speed the evolution of resistance, further impeding the ability to use these agents for long-term disease control.

To address this problem, Hockett said his lab will examine the use of naturally produced toxins and termed tailocins – bacterial proteins that can inhibit or destroy harmful bacteria – to prevent disease and support plant disease resistance.

“The project will result in an understanding of how pathogen populations withstand different types of membrane disruption, and in turn, which treatments could be used in combination to mitigate these effects,” he said. “Our long-term goal is to understand the prevalence and mechanisms of these survival strategies to maximize the efficacy of membrane-disrupting antimicrobials and minimize the potential for resistance.”

Carolee Bull, professor and head of the Department of Plant Pathology and Environmental Microbiology, said the work of Hockett and his team is important in addressing “this novel issue in resistance management in plant health.”

Hockett will be aided by Prem Kandel, postdoctoral scholar in Penn State’s Department of Plant Pathology and Environmental Microbiology; Lindsay Triplett, agricultural scientist in the Department of Plant Pathology and Ecology, Connecticut Agricultural Experiment Station; and Connie Chang, an associate professor in the Department of Chemical and Biological Engineering, Montana State University.

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