PARENT SESSION
Oral Session 15: Soil Ecology I: Mycorrhizal Communities.
Presiding: V Borowicz and X He
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room D 137.
Ectomycorrhizal diversity in a loblolly pine (Pinus taeda L.) genetics plantation: Influence of fertilization.
Burke, David*,1, Martin, Kendall2, Rygiewicz, Paul3, Topa, Mary1, 1 Boyce Thompson Institute, Ithaca, NY2 Center for Environmental Diagnostics and Bioremediation, University of West Florida, Pensacola, FL3 USEPA National Health and Environmental Effects Research Laboratory, Corvallis, OR
ABSTRACT- Loblolly pine (Pinus taeda L.) has co-evolved a high dependency on ectomycorrhizal (ECM) associations most likely because its natural range includes soils of varying moisture that are P- and/or N-deficient. Because of its wide geographic distribution, we would expect its roots to be colonized by a high number of ECM fungi, even in monoculture forests. We compared potential differences in the ectomycorrhizal (ECM) community composition of slow- and fast-growing families of loblolly pine from drought-hardy Texas and mesic Atlantic Coastal Plain ecotypes, and how these fungal communities responded to fertilization in a common garden setting in North Carolina. Root tips from soil cores collected in autumn of 2002 were harvested, and DNA representing soil fungal communities was amplified using labeled primers targeting rRNA genes which have taxonomic significance. Labeled amplicon was used to generate terminal restriction fragment length polymorphisms (T-RFLP). This technique permits accurate molecular fingerprinting of species-types in complex communities. Correspondence trends suggested a possible influence of genotype on some ECM. However, our small sample size precluded rigorous testing for family differences and plant genotype did not significantly influence species richness and diversity (PIE). Fertilization significantly decreased species richness and diversity (PIE) and appeared driven by significant increases in the relative abundance of two identified fungal phylotypes with sequence affinity for the Thelephorales. These results suggest that fertilization may alter the composition of ectomycorrhizal communities toward exploitive, early colonizing fungal types, thereby reducing overall species richness and diversity of these important fungal mutualists.
Key words: community structure, ectomycorrhizae, T-RFLP