New Harvard Forest Publication: Garlic Mustard Suppression of Mutualistic Fungi Stronger in North America Than Europe

Harvard Forest Ecologist Kristina Stinson, along with former Bullard Fellow John Klironomos (University of Guelph) and researchers at University of Montana and Wright State University, followed up recent work on the antimicrobial properties of the invasive plant, Alliaria petiolata (garlic mustard). Their forthcoming paper in the journal Ecology provides new evidence for a novel mechanism by which garlic mustard disrupts below-ground mutalisms between plants and their beneficial microbes. As one of North America's most aggressive invaders of undisturbed forests, garlic mustard is known to inhibit mycorrhizal fungal mutualists of North American native plants. The authors tested whether these inhibitory effects on mycorrhizas in invaded North American soils are stronger than on mycorrhizas in European soils where A. petiolata is native. They found that suppression of North American mycorrhizal fungi by A. petiolata corresponds with severe inhibition of North American plant species that rely on these fungi, whereas congeneric European plants are only weakly affected. The chemicals involved were identified as a combination of flavinoids and glucosinolates. These results indicate that antifungal phytochemicals, benign to resistant mycorrhizal symbionts in the home range, impose a novel threat to native North American plant species.

Callaway, R.M., D. Cipollini, K. Barto, G.C. Thelen, S.G. Hallett, D Prati, K. Stinson and J. Klironomos. 2008. Novel Weapons: Invasive Plant Suppresses Fungal Mutualists in America but not in its Native Europe. Ecology.