LB 30-257 - The effect of rising temperature on the symbiotic relationship between Carex vulpinoidea and mycorrhizal fungi

Mycorrhizae are species of fungi that form mutualistic relationships with many plants. These fungi colonize the rhizosphere where roots interact with the soil microbiome. Mycorrhizal fungi are known to provide nutrients, especially phosphorus, to the host plants, while the plants provide carbohydrates to the fungi. These fungi benefit the host plants during times of environmental stress by assisting with water absorption, growth, disease resistance, and nutrient reallocation. Climate change is expected to broadly reduce soil fertility through changes in soil microbial communities, soil moisture and structure, nutrient cycling, and soil organic matter. In fungi alone, warming is linked with changes in biomass, spore production, mycelial growth rate, and metabolic rate. In plants alone, heat stress can lead to reductions in the plant biomass and the roots’ respiration rate, changes in leaf traits like mass and thickness, and even increases in photosynthetic rate. But plants and mycorrhizae together may be less sensitive to warming. To complicate matters further, mycorrhizal fungi compete with one another to colonize a host plant’s roots, with the host plant mediating and influencing those competitive interactions. It remains unclear how these complex plant-mycorrhizal relationships will change in a warming world. In this study, the plant Carex vulpinoidea has been selected as the study species for its observed responsiveness to mycorrhizal fungi. For this project, five seedlings were planted into pots filled with a sterilized 50:50 mixture of sand and topsoil. Each pot was placed into a dip tray filled with water to saturate the soil. Pots were placed in pairs containing one pot inoculated with a blend of several species of mycorrhizal fungi and the other without. Half of the twelve pairs were placed on heating pads to simulate a warmer environment. Preliminary results suggest that inoculation with mycorrhizal fungi increased the height of the plants and the number of leaves per plant but decreased the number of shoots per plant. An increase in the conductivity of the water for inoculated pots was also observed.