Ectomycorrhizae are symbioses between many important forest trees such as Douglas-fir and so called ectomycorrhizal fungi. The symbiosis is mutually beneficial to both partners, and neither can survive without the other. The trees provide carbohydrates to the fungi while the fungi facilitate nutrient uptake for the trees. Ectomycorrhizal fungi are taxonomically much more diverse than their tree hosts, but it remains largely unclear whether the different species of fungi differ in the functions they fulfill for the tree hosts and the forest ecosystem or whether they are "functionally redundant". In addition to trees and fungi, bacteria have also been shown to live in close association with ectomycorrhizae, but have rarely been investigated, and it remains unclear whether and how they affect the functioning of the symbiosis. As a first step in assessing the potential influence of bacterial populations on the functional diversity of ectomycorrhizal fungi, the author of this proposal will study how bacterial diversity is structured between different species of fungi and different individuals within a species. Methods will be developed to measure the genetic diversity of bacteria directly from mycorrhizae thus avoiding the bias introduced by bacterial cultivation in the laboratory. By incorporating bacteria into the functional equation, this research will take the science of ectomycorrhizal ecology into a whole new direction.
