PARENT SESSION
Wednesday, August 9, 1:30-5:00 pm
COS 74 - Mycorrhizal ecology
Heritage Ballroom I, Marriott
Presiders: J Sharma
Ericoid mycorrhizal fungi of arctic tundra differ in their ability to use different sources of nitrogen.
Aldrich-Wolfe, Laura*,1, Simpson, Nicholas1, Walker, John2, Trowbridge, Justin1, Barbare, Holly1, Jumpponen, Ari1, 1 Kansas State University, Manhattan, KS2 Appalachian State University, Boone, NC
ABSTRACT- Most plants in natural ecosystems rely on symbiotic fungi for nutrient uptake. The importance of this symbiosis for nitrogen uptake is likely greatest in ecosystems such as arctic tundra, where most nitrogen occurs in organic form and nitrogen mineralization is low. Ericaceous plants are a conspicuous component of tundra communities. Understanding functional diversity of ericoid mycorrhizal (ErM) fungi is essential to elucidating plant nitrogen acquisition in arctic ecosystems. We used culture- and DNA-based techniques to characterize the ErM fungal community in tundra near Toolik Lake, Alaska at the Arctic Long-Term Ecological Research site. The ErM fungal community differed from those described for other ecosystems. Fungi forming ErM structures within roots of five common ericaceous plant species fell in lineages not previously described as ErM, and fungi typically dominant in other ecosystems were absent. To test for diversity among ErM fungi in nitrogen acquisition, we grew isolates (of the most frequently detected species) in liquid culture with different inorganic and organic nitrogen sources. We observed both inter- and intra-specific variation in growth on different nitrogen sources. Frequently, variation among isolates within a species exceeded variation observed between species. Isolates of the most frequently detected fungus, Phialocephala fortinii, grew poorly on ammonium and varied in their performance on amino acids known to be abundant in soil at the field sites (aspartic acid, glycine, serine, threonine). Our work suggests that variation among ErM fungi in use of different nitrogen sources may play a role in maintaining fungal diversity in arctic tundra.
Key words: mycorrhizal ecology, nutrient uptake, arctic tundra