Nutrient Cycling in the Rhizosphere, an Important Consideration for Carbon Sequestration in Trees

Carbon sequestration in plants has been proposed as a possible moderator or solution to the rising levels of atmospheric carbon dioxide (CO₂) that threaten to alter global climate.  However, it is becoming clearer that nutrient uptake is often a limiting factor in the ability of plants to capture, allocate, and provide long-term storage of CO₂ in the form of both above-ground and below-ground biomass.  Symbiotic relationships between trees and the soil community are critically important links through which nutrients are cycled in forest ecosystems.  Consequently, our research aims to provide system-scale models of symbiotic interactions between deciduous trees (Populus tremuloides), ectomycorrhizal fungi (Laccaria bicolor), and mycorrhizal helper bacteria (Pseudomonas fluorescens) in response to environmental nutrient availability.  Here, we employ a controlled laboratory system with which targeted proteomics, biochemical assays, and ChIP-seq characterization of carbon, nitrogen and phosphorous regulators are used to identify symbiosis-specific molecular mechanisms that control carbon management and allocation.  Such approaches are building a better understanding of how metabolic and regulatory processes in the rhizosphere translate to improved nutrient uptake and net primary productivity of trees, ultimately serving as an important reminder that healthy soils provide forests the ability to uptake the nutrients needed to accumulate biomass and efficiently sequester carbon.