A team of plant scientists at Penn State’s College of Agricultural Sciences received a $1.96 million, five-year grant from the National Institutes of Health to study how beneficial relationships between plants and bacteria evolve and persist, according to an April 14 announcement.
The grant supports research into mutualisms—relationships where both partners benefit—which could have important implications for agriculture and environmental health. The project is funded through a Maximizing Investigator’s Research Award, which backs a laboratory’s long-term vision rather than individual projects.
“Most research focuses on harmful microbes known as pathogens, but this team studies mutualisms — relationships in which both partners benefit,” said Liana Burghardt, assistant professor in the Department of Plant Science and director of the Huck Center for Root and Rhizosphere Biology. Her lab investigates the partnership between Medicago truncatula (barrel medic) and Sinorhizobium meliloti bacteria—a model system for understanding legume biology, nitrogen fixation, and symbiotic partnerships closely related to alfalfa.
Burghardt explained that these bacteria infect plant roots, leading to nodule formation where atmospheric nitrogen is converted into nutrients usable by the plant while the bacteria receive sugars as food. “In other words,” she said, “the plant gets nutrients and the bacteria get energy and a place to live.” She added that these beneficial partners can live independently in soil but re-form their relationship with each new generation: “Bacteria spend much of their time in soil, not inside plants. This creates a complex situation where bacteria must survive in soil, compete to infect plants and adapt to different plant hosts.”
The research aims to answer three main questions: what genes help bacteria succeed inside plants; what happens outside the host; and how these partnerships remain stable over time. The team uses whole-genome sequencing combined with lab and field experiments to track bacterial strains’ success rates over generations.
“A win-win from the lab’s perspective is that this knowledge also could improve agriculture by advancing the engineering of nitrogen-fixing bacteria that thrive in soil and benefit plants,” Burghardt said. She also noted broader applications: “We need to understand how and why beneficial microbes support health in general ecosystems… Our long-term goal is to use helpful microbes to improve the health of plants, animals and environments.”
Other members involved include postdoctoral researchers Sohini Guha and Kayla Clouse; lab manager Cody DePew; graduate students Jennifer Harris, Maria Alejandra Gil-Polo, Patrick Sydow, Kelsey Mercurio, and Amanda Jason.
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