PARENT SESSION
Oral Session #102: Soil Ecology: Mycorrhizae .
Presiding: N. Johnson
Friday, August 9. 9:00 AM to 12:00 PM. Apache Meeting Room, TCC.
Orchid mycorrhizal diversity and tolerance of spatial and temporal habitat variation.
McCormick, Melissa*,1, Sloan, Dan1, O'Malley, Kelly1, Whigham, Dennis1, O'Neill, John1, 1 Smithsonian Environmental Research Center, Edgewater, Maryland
ABSTRACT- In obligate mycorrhizal associations, diversity of suitable fungi can affect plant distribution by affecting the diversity of suitable habitats and tolerance of environmental change. Orchids depend entirely on mycorrhizal fungi for nutrition for the first stage of their lives. We examined the effect of fungal diversity on Goodyera pubescens and Liparis lilifolia growth across a range of media. All fungi were distinct, but fungi from G. pubescens encompassed greater genetic diversity than those from L. lilifolia. Greater fungal diversity allowed G. pubescens to maintain more equal growth across media than L. lilifolia. This suggests that greater fungal diversity may allow G. pubescens to grow in a wider range of habitats than L. lilifolia. If G. pubescens could associate with multiple fungi at once or switch among fungi if conditions changed, then its diverse fungi could allow it to tolerate environmental change. Using DNA fingerprinting, we found that adult field plants each associated with a single fungal individual. Some protocorms grown with one fungus were able to switch to a second fungus, but only after eliminating the first fungus. More than 70% of protocorms were unable to switch fungi and died. We concluded that diversity of fungal associates may affect the ability of temperate, terrestrial orchids to grow in diverse habitats, but likely has little effect on tolerance of environmental change.
KEY WORDS: orchid mycorrhiza, fungal diversity, Goodyera pubescens, Liparis lilifolia