Characterizing the Impact of Arbuscular Mycorrhizal Fungi Inoculation on Rhizosphere Microbial Community Structure During Plant Establishment in Metalliferous Mine Wastes
Metalliferous mine tailings pose a challenge to revegetation efforts due to low pH, metal toxicity, poor soil structure, and low nutrient content. Arbuscular mycorrhizal fungi (AMF) are obligate plant root symbionts known to improve plant health and to mitigate the effects of several of those stressors. In mine tailings, inoculation with AMF improves plant biomass and resistance to metal stress, particularly when combined with compost amendment. Previous qualitative studies also indicate that different AMF inoculum species effect fungal and bacterial community structures. By coupling taxonomic rhizosphere data generated from the ongoing Iron King Mine and Humboldt Smelter Superfund Site (IKMHSS) field trial and controlled greenhouse studies, AMF species with traits advantageous to phytostabilization can be identified. These isolates may then be utilized in future revegetation efforts to improve plant tolerance to stressors. My first experiment will be to characterize the taxonomic differences in the rhizosphere of mesquite seedlings inoculated with a variety AMF species grown in 15% compost amended tailings from the IKMHSS. AMF treatments will include three species isolated from low pH (<5.5) and metal impacted soils, two species isolated at a neutral pH (>5.5), and a commercially available mixed inoculant of several AMF species applied independently. These systems will also be compared to uninoculated mesquite trees grown on the same tailings-compost mixture. Each treatment will be analyzed for shoot metal uptake, plant biomass, AMF root colonization, and rhizosphere community structure through iTag sequencing for the bacterial 16S gene and fungal ITS region.