Projects from the laboratory
  • Date: 27 Apr 2024

Wetlands are complex ecosystems having important functions that are driven by many physical, chemical, and biological processes with implications at local, regional and global level. Biogeochemical processes that occur at the interface between plant roots and the soil are widely recognized for their important role in the functioning of wetland ecosystems. In this context, ROOTARMOUR aims at providing novel insights into the involvement of root iron plaques (IP) – oxide coatings precipitated on the root surface under anoxic soil conditions – as hotspots of iron (Fe), phosphorus (P) and carbon (C) cycling in redox-dynamic environments. By building on a conceptual model of element redox cycling in the rhizosphere and focusing on rice as a model wetland plant, we aim at elucidating how multiple biotic and edaphic factors are implicated in root IP formation and related functions. The effects of changes in root traits induced by different P availability, in combination with the presence of soil or plant-derived dissolved organic matter, on the chemical, mineralogical and structural variability of these Fe oxyhydroxide coatings will be evaluated at an unprecedentedly high spatial and temporal resolution. This will be made possible by combining root trait evaluation, microsensor and imaging approaches, C-stable isotope tracing and X-ray microanalytical techniques in order to follow 13 spatiotemporal changes in O and P gradients, and plant C allocation patterns in the rhizosphere, as well as the root morphology and 2 distribution of Fe and P on the root surface. Additional empirical evidence for the underlying processes will also be provided by utilising artificial root systems that will allow to study the effects of specific variables on the interactions between Fe, P and C cycling at the root surface through a reductionist approach. Furthermore, these effects will be linked with specific IP-related functions, namely P availability and plant uptake, microbially-mediated Fe cycling in the rhizosphere, as well as organic matter turnover and stabilization in the root detritusphere. ROOTARMOUR is therefore expected to shed light on understudied rhizospheric processes that could have important implications on the productivity, resilience and environmental sustainability of wetland ecosystems.

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