Shifts in ectomycorrhizal (ECM) community structure were examined across an experimental hydrologic gradient on containerized seedlings of two oak species, Quercus montana and Quercus palustris, inoculated from a homogenate of roots from mature oak trees. At the end of one growing season, seedlings were harvested, roots were sorted by morphotype, and proportional colonization of each type was determined. DNA was subsequently extracted from individual root tips for polymerase chain reaction, restriction fragment length polymorphism, and rDNA sequencing of the ITS1/5.8S/ITS2 region to determine identities of fungal morphotypes. Twelve distinct molecular types were identified. Analysis of similarity showed that ECM fungal assemblages shifted significantly in composition across the soil moisture gradient. Taxa within the genus Tuber and the family Thelephoraceae were largely responsible for the changes in fungal assemblages. There were also significant differences in ECM community assemblages between the two oak host species. These results demonstrate that the structure of ECM fungal communities depends on both the abiotic and biotic environments and can shift with changes in soil moisture as well as host plant, even within the same genus.
Bibliographical noteFunding Information:
Acknowledgements We thank Joe Morton at the University of West Virginia for providing assistance with the morphotyping and digital image collection and Thomas Bruns at the University of California Berkeley for the use of his laboratory for the molecular work. Funding was providing by a Smithsonian Institution fellowship to J. Cavender-Bares, by the University of Minnesota, and by an NSF REU grant to SERC that supported R. Robinson’s summer internship. We thank Sara Branco, Ian Dickie, and two anonymous reviewers for the comments that significantly improved the manuscript. We also thank Nicole Cavender and Kari Koehler for other assistance.
- Community assembly
- ITS region
- Molecular typing
- Q. palustris
- Quercus montana
- Soil moisture gradient