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Metabolic fate of a bacterial siderophore in Arabidopsis thaliana and Pisum sativum in relationship with iron status in plants
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Prod 2018-15 SPE EA BIOME INRA DOCT. National audience. Despite its abundance, iron is weakly bioavailable for organisms due to its poor solubility in soils under aerobic conditions. Therefore, plants and other organisms have evolved mechanisms to efficiently assimilate iron from the soil. Non-grass plants use a strategy (strategy I) based on soil acidification, reduction of the Fe3+ in Fe2+ which incorporated in the roots by iron transporters. We previously showed (Shirley et al., 2011; Vansuyt et al., 2007) that iron nutrition and growth of a strategy I plant could be promoted by the ferric-complex of the pyoverdine (Fe-pvd), a siderophore produced by microorganisms. If pyoverdine was further localized in planta using different immunological technics, mechanisms involved in the uptake of the model ferric-pyoverdine and its fate in planta remained still unknown. To better understand how strategy I plant use pyoverdine for their iron nutrition, X-ray fluorescence (XRF) imaging and Fe K-edge XANES analyses were conducted on LUCIA beamline under cryo-conditions on two models of plant: Arabidopsis thaliana and Pisum sativum. Collection of XRF maps on stems and roots thin sections of pea at various culture times and under several Fe supplies, including Fe-pvd, allowed direct Fe localization through the organs. XANES spectra obtained on freeze-dried and grounded stems and roots of A. thaliana at various culture times were fitted using a set of selected Fe reference compounds. These preliminary results are promising and provide inside on Fe-pyoverdine take-up, its chemical evolution and its translocation from the roots to the shoots.
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