Print PageUnderstanding how variation among host plant genotypes influences interactions with associated communities of symbionts is an important goal of ecological genetics. In particular, the mechanisms by which plant genotypes differentially influence mycorrhizal communities, and the possible resulting feedbacks, are poorly understood. We hypothesized that 1.) communities of ectomycorrhizal fungi differ among tree genotypes, 2.) that variation in litter chemistry maybe one way in which tree genotype influences its ectomycorrhizal community, 3.) genotype variation in mycorrhizal fungal associations can result in differential feedback and plant growth. To address these hypotheses, we coupled a common garden study of adult trees, with greenhouse inoculation experiments, to understand the links among Populus angustifolia (narrowleaf cottonwood) genotype, genetically-based tree traits such as productivity and litter secondary chemistry, and ectomycorrhizal fungal communities.
Results/Conclusions
Our findings indicate: 1.) Ectomycorrhizal fungal colonization and species composition vary among tree genotypes, whereas species richness does not. 2.) Ectomycorrhizal communities covary strongly with tree productivity but are not strongly tied to genetic variation in leaf litter chemistry. 3.) Variation among tree genotypes in colonization of ectomycorrhizal fungi leads to differential growth of genotypes. These result support patterns frequently observed with aboveground plant-associated communities, such as herbivores, that tree genotypes can have a significant structuring effect on associated communities. Furthermore, it demonstrates that the outcome of interactions between mycorrhizal fungi and their host plants can be contingent on tree genotype identity, but that secondary chemistry in leaf litter does not seem to influence interaction between host trees and ectomycorrhizal fungi in a riparian ecosystem.
phone 202-833-8773