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18th International Symposium on Iron Nutrition and Interaction in Plants
Madrid – May 30-June 3 2016
THE GEOCHEMISTRY OF STRATEGY II PLANT IRON UPTAKE
Stephan M. Kraemer*, Walter Schenkeveld
Department of Environmental Geochemistry and Environmental Research Network, University of Vienna,
Althanstrasse 14, 1090 Vienna, Austria.
*[email protected]
ABSTRACT: While some underlying basic problems and fundamental biogeochemical and physiological
solutions to plant iron acquisition from soils have been explored by pioneering research over several
decades, a full mechanistic, quantitative and predictive understanding of the pertinent plant soil interactions
is still lacking. Any physiological activity at the root surface addresses a complex and highly non-linear
biogeochemical reaction network. Interactions and feedback loops between root activity and soil reactivity
are inherently difficult to understand – the co-location of the soil/root interface with scientific disciplinary
boundaries constitutes just one impediment - but the intellectual challenges associated with this issue also
provide an exciting field for scientific research.
This presentation gives an overview over soil biogeochemical aspects of plant iron acquisition with a
particular focus on Strategy II iron acquisition mechanisms. It is shown that specificity of the acquisition
mechanism for the target nutrient iron is of high importance for the efficiency of the process. However,
specificity is usually understood in terms of thermodynamic properties of the ligand and its iron complex
versus other metal complexes. Here, the concepts of thermodynamic versus kinetic specificity are explored,
based on the coordination chemical properties of biogenic ligands and their interaction with the soil chemical
reaction networks. This discussion leads to an understanding of the time dependence of iron mobilization
processes that we conceptualize as a concentration/time window of iron acquisition. An overview of
processes and feedbacks constraining this window of iron acquisition is given. Also, scaling problems are
discussed that may lead to wrong conclusions if the non-linear effects of experimental parameters are not
properly considered.
Keywords: Rhizosphere, geochemistry, window or iron uptake, phytosiderophores, kinetics
ACKNOWLEDGEMENT Funding for this work is provided by the Austrian FWF grant
Preferred Presentation format: (ORAL (invited)).
Selected Sessions: (please, indicate the name of the session from these):
•
Iron chemistry and dynamics in soils
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I 1528-N19.