Diversity in root‐associated fungal communities isolated from Rhododendron maximum in the southern Appalachian mountains

Toyota Auditorium, Howard H. Baker Jr. Center for Public Policy

In recent years, Rhododendron maximum has become a dominant understory shrub in the southern Appalachian mountain range. This has profound implications for the future structure of the forest canopy, because R. maximum reduces understory diversity and tree seedling recruitment by creating dense shade. The chemistry of the soil beneath R. maximum is altered by the deposition of litter containing phenolic compounds, some of which are broken down and returned to the shrubs by the ericoid mycorrhizal communities associated with their roots. This community of fungi is essential to the success of R. maximum, as the fungi allow the plants to thrive in nutrient-poor soils by acquiring nitrogen from organic sources. We expect that there are differences in the edaphic conditions across the growing season that may affect diversity and community composition of the associated fungi. In this study, I attempt to identify the 2 fungi that make up these communities and to reveal whether there is a seasonal shift in community structure over the course of a year. I sampled roots during the spring, summer, and fall of 2011 from two transects of ten R. maximum plants each located at the Gilley Research Station in North Carolina. I extracted genomic DNA from the fungi isolated from root sections and amplified the ITS region of the samples from the spring and summer. I will analyze and present an initial comparison of the diversity and composition of the fungal communities associated with R. maximum across the first two seasons.