Document: JEF-3-58-32

Arbuscular mycorrhizal specificity, compatibility, and feedback between co-occurring species in a tallgrass prairie.

CASTELLI, J.P.*

University of Pennsylvania, Philadelphia, PA 19104 USA 1

Abstract:
Despite having the potential to mediate species diversity within natural systems, feedback between plants and the soil microbial community remain relatively unexplored. While patterns of specificity between arbuscular mycorrhizal fungal (AMF) and plant species have been documented in many systems, evidence for a link between these patterns and potential soil feedbacks are lacking. In this study the AMF communities associated with Schizychrium scoparium and Andropogon gerardii were compared for their compatibility with individuals of each plant species using reciprocal root inoculations. Individuals of both plant species had significantly higher root infection by the AMF associated with conspecifics, but achieved a significantly higher biomass when grown with the AMF associated with the other species. This implies that individuals of these plant species are culturing AMF which are "over" infective towards conspecifics creating a negative plant-soil feedback. These results were consistent in both greenhouse and field experiments, but only when plants and fungi were grown in the same soil from which the fungi were isolated. This illustrates the importance of examining mycorrhizal relationships in biologically relevant soils. Characterization of the AMF communities associated with each species based on spores isolated from field, trap culture, and experimental soils revealed little differences besides the preferential association of S. scoparium and Glomus intraradices. The overall lack of species-level specificity observed between the two AMF communities was surprising given the significant differences in plant species compatibility they demonstrated.

Keywords: mycorrhiza, specificity, compatibility, feedback, grasses

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This abstract is being presented at: 9:30 AM in session:
Oral Session #8: Mycorrhizal Fungi.