(176p) Comparing Arbuscular Mycorrhizal Fungal Strains for Enhanced Carbon Sequestration in Agricultural Systems

Plants engage in symbiosis with arbuscular mycorrhizal fungi (AMF) to exchange plant-derived carbon for essential plant inorganic nutrients, such as nitrogen and phosphorus. This symbiosis may improve plant tolerance to abiotic and biotic stresses and sequester carbon in the form of root and microbial biomass. The carbon cost of this nutrient exchange and the partitioning of plant-derived carbon to fungal storage organs likely depends on the AMF species or strain. A better understanding of the fate of carbon within various plant-AMF systems will enable the optimization of AMF consortia for carbon sequestration and plant growth. However, quantification of AMF effects on plant carbon allocation is limited, and most methods require destructive sampling. Here, we combine X-ray computed tomography (XCT) and positron emission tomography (PET) to observe and quantify in situ the flow of 11-carbon from leaves to roots to hyphae. In a corn-Rhizophagus irregularis system, R. irregularis induced an increase in carbon allocated to the corn root system compared to uninoculated controls. Co-registered XCT and PET images suggest the increase in carbon correlates with increased lateral root growth near the inoculation site. While the increased number of lateral roots account for some of the ¹¹C signal increase, the remaining carbon is allocated to microbes including AMF. Using this in situ method, I compare different arbuscular mycorrhizal fungal strains to identify strains that increase belowground carbon allocation. This work deepens our understanding of resource exchange during corn-AMF symbiosis and enables future studies on the impact of plant and fungal genetics on carbon allocation in plant-AMF symbioses.