Block title

Spotted Knapweed (Centaurea stoebe) is a noxious weed from Eurasia that has invaded MPG Ranch. These invasions may be aided by soil-dwelling arbuscular mycorrhizal fungi (AMF) because knapweed becomes more successful than native plants in the presence of AMF. It is suspected that knapweed is exploiting fungal symbiosis somehow, but the mechanism is unknown. In collaboration with Dr. Matthew Whiteside from University of British Columbia, we designed an experiment to calculate the cost-benefit relationship of mycorrhiza when knapweed is competing with native grasses. We will measure carbon allocation from plants to fungi by stable isotope probing, and reciprocal phosphorus delivery from fungus to plant using fluorescent nanoparticles. Combining these methods will help us to determine if knapweed truly pays its dues to the fungus, or is a successful cheater.

Picture 1: Half the plants in each pot are labeled with non-radioactive 13CO2 gas that the plants incorporate through photosynthesis. We can then trace this carbon source throughout the plant and measure how much is allocated to the soil in general and to AMF in particular.

Picture 2: Quantum dots fluoresce under UV-light and can be bound to any molecule. We use phosphorus-labeled quantum dots that we add to pots to trace P movements from AMF to plants.

About the Author

Ylva Lekberg

Ylva graduated from the Swedish University of Agricultural Sciences with a M.Sc. in Biology and Horticulture in 1996 and a Ph.D. in Ecology from Penn State University in 2004. She received the Alumni Association Dissertation Award for her work in agroecology and subsistence farming in Sub-Saharan Africa. Post-doctoral positions at Montana State University and later at Copenhagen University as a Marie Curie Fellow have allowed her to explore the role of mycorrhiza, a root-fungus symbiosis, for geothermal plants in Yellowstone National Park and coastal grasslands in Denmark. Her research has been published in journals such as Ecology, Journal of Ecology and New Phytologist.

Ylva currently works at MPG Ranch as a soil ecologist. She explores the role of mycorrhiza in the success of exotic plants and examines the use of specific pathogens to combat invasions. In her spare time Ylva mountain-bikes, plays soccer, and maintains a large vegetable garden.