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Going Underground

Hired to join CBS’ new fungal evolution research cluster, Peter Kennedy studies competition within underground networks of fungi that determine what trees grow in a forest.

While trees certainly appear to be the leading species in a forest, lowly mushrooms huddled in their shade on the forest floor are really calling the shots. Fruiting bodies above ground are produced by a massive network of roots and branches below that determine the type of trees on a given landscape and provide the nutrients they need to thrive.

As a child, Peter Kennedy collected mushrooms with his father on Bainbridge Island near Seattle, where he grew up. But he didn’t recognize their symbiotic relationship with trees until years later, when he was a research assistant working in a tropical cloud forest in Panama.

When he began graduate studies at the University of California, Berkeley, Kennedy decided to focus on these intriguing fungi, called ectomycorrhizas (ECMs). He soon learned that many forest mushrooms are ECMs and that these fungi co-evolved with certain tree species. ECMs form sock-like sheaths around tree roots with filaments that reach into the soil. The filaments help the roots absorb water and nutrients; in exchange, trees provide fungi with carbohydrates.

At the time, mycologists still relied on the proximity of mushrooms to trees to identify their connection. But Kennedy was able to use new DNA fingerprinting techniques to identify fungi in soil and on tree roots. These techniques allow him and other researchers to confirm the type and quantity of ECMs in soil and roots adjacent to trees, to map their networks, and to measure how competition affects the composition of ECMs in a forest.

It takes lots of soil samples to map ECM networks, so Kennedy frequently enlists undergraduates to help with the collection. You could say it’s a symbiotic relationship. In exchange, students get valuable field experience, learn how to do DNA-based laboratory work, and are often included as co-authors on published papers.

As an assistant professor of biology at Lewis & Clark College in Portland, Oregon for several years, Kennedy enjoyed working with undergraduates. As a new associate professor in the College of Biological Sciences’ (CBS) Department of Plant Biology, he’s happy he will continue to engage them in his work.

Moreover, he’s thrilled by all the opportunities the University of Minnesota offers for collaboration. There are many biologists spread across a range of departments in the College of Biological Sciences (CBS) and the College of Agricultural, Food and Natural Resource Sciences (CFANS) who study fungi, including Georgiana May, Department of Ecology, Evolution and Behavior; Jonathan Schilling, Department of Bioproducts and Biosystems Engineering; Scott Bates, Melania Figueroa, and Bob Blanchette, Department of Plant Pathology; and Corby Kistler in the U.S. Department of Agriculture Cereal Disease Lab. Kathryn Bushley, another new mycologist from the fungal evolution cluster hire, will be joining them soon from Oregon State University. In addition, there’s a concentration of faculty in CBS and CFANS who study nitrogen fixation, which is related to Kennedy’s research. He also hopes to work with Sarah Hobbie (Ecology, Evolution and Behavior), a National Academy of Sciences member who studies decomposition in soil. And he’s excited about exploring the rich diversity of mushroom species that grow in Minnesota.

“The University of Minnesota has become a major hub for the study of fungal biology in both natural ecosystems and agriculture,” he says. “And the number of biomes represented in this area makes it ideal for studying the role that fungi play in mediating the movement of biomes as climate changes.”

While Kennedy is primarily interested in basic research to understand the role of fungi in nature and the mechanisms that allow them to fulfill that role, he believes his work will have benefits for agriculture as well as helping forests adapt to climate change and re-establishing forests on cleared land.

Colleague Corby Kistler calls Kennedy “… an innovative scientist whose work occupies a unique space equally grounded in the disciplines of fungal ecology and evolution. Peter’s ability to synthesize ecological concepts with evolutionary theory sets him apart and makes him a key member of the expanding team of fungal biologists at the University of Minnesota.”

After completing his Ph.D. at U.C. Berkeley, Kennedy did a post-doctoral fellowship at the Point Reyes National Seashore and studied mycorrhizal symbioses in Mexican forests on a Fulbright Fellowship. He and his wife, Martha, have two young children and live in University Grove.

— Peggy Rinard