Graduate Student Miami University Oxford, Ohio, United States
Abstract: Many plant species allocate carbon to mycorrhizal fungi symbionts as a part of their nutrient acquisition and growth strategies. These symbiotic relationships are notably complex, but researchers have made some progress on understanding how variation for mycorrhizal establishment and responsiveness is structured across the plant kingdom. The goals of this study are to highlight two under-researched components of this variation: intraspecific trait variation in plant species for symbiosis functioning traits (i.e., growth and nutrient uptake responses) and differences in allocation of mycorrhizal benefits across the plant kingdom. I will present the results of meta-analytical work that shows that variation for growth and nutrient responses to mycorrhizal fungi within plant species can be equal in magnitude to that found across the entire plant kingdom. I will also present work from a greenhouse experiment that identifies two tradeoff axes for plant trait responses to mycorrhizal fungi. The first axis is defined by allocation to aboveground plant biomass, the primary trait used to assess benefits received from mycorrhizal fungi. The second axis describes allocation to roots, and this axis was not associated with aboveground biomass response. These results indicate that only using mycorrhizal growth response as a proxy for mycorrhizal responsiveness may dramatically underrepresent the functional importance of mycorrhizal symbiosis in some plant species. Finally, I will present preliminary results on the variation of mycorrhizal communities within the roots of hundreds of switchgrass genotypes. This variation in mycorrhizal community assembly is likely functionally important and is the result of local adaptation to soil and environmental conditions. Our work provides evidence that selection for mycorrhizal traits occurs primarily within species and that many plant species are highly variable for these traits.
