caa a22 4500 47711153X CHVBK 20180405111610.0 cr unu---uuuuu 170330e19960301xx s 000 0 eng 10.1007/BF00015411 doi (NATIONALLICENCE)springer-10.1007/BF00015411 Critical evaluation of organic acid mediated iron dissolution in the rhizosphere and its potential role in root iron uptake [Elektronische Daten] [David Jones, Peter Darah, Leon Kochian] Both experimental extractions and theoretical calculations were undertaken to assess whether organic acid-mediated Fe dissolution could play a significant role in elevating the concentration of Fe-complexes in the rhizosphere, and further, whether this could satisfy the Fe demands of a plant utilizing ferric reduction to acquire Fe. Using a mathematical computer model, it was predicted that organic acids released from and diffusing away from the root would result in a solution organic acid concentration at the root surface of between 1 to 50 μM. Over 99% of the organic acids lost by the root were predicted to remain within 1 mm of the root surface. The experimental results indicated that citrate-mediated Fe dissolution of amorphous Fe(OH)3, was rapid in comparison with citrate dissolution of the Fe-oxides, Fe2O3 and Fe3O4. The rate of citrate and malate mediated Fe-dissolution was dependent on many factors such as pH, metal cations and phosphate saturation of the Fe(OH)3 surface. At pH values ≤6.8, citrate formed stable complexes with Fe and dissolution proceeded rapidly. Under optimal growth conditions for a plant utilizing a reductive-bound mechanism of Fe acquisition (dicots and non-grass monocots), it can be expected that citrate and malate may be able to satisfy a significant proportion of the plant's Fe demand through the formation of plant-available organic-Fe3+ complexes in the rhizosphere. In high pH soils (pH≥7.0), the plant must rely on other sources of Fe, as citrate-mediated Fe dissolution is slow and Fe-citrate complexes are unstable. Alternatively, the root acidification of the rhizosphere could allow the formation of stable Fe-organic complexes. ei]H Marschner Kluwer Academic Publishers, 1996 citrate nationallicence iron nationallicence organic acids nationallicence rhizosphere nationallicence root nationallicence Jones David U.S. Plant Soil and Nutrition Laboratory, USDA-ARS, Cornell University, 14853, Ithaca, NY, USA aut Darah Peter Department of Plant Sciences, University of Oxford, OXI 3RB, Oxford, UK aut Kochian Leon U.S. Plant Soil and Nutrition Laboratory, USDA-ARS, Cornell University, 14853, Ithaca, NY, USA aut Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl 180/1(1996-03-01), 57-66 0032-079X 180:1<57 1996 180 11104 https://doi.org/10.1007/BF00015411 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00015411 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Jones David U.S. Plant Soil and Nutrition Laboratory, USDA-ARS, Cornell University, 14853, Ithaca, NY, USA aut NATIONALLICENCE 700 1- Darah Peter Department of Plant Sciences, University of Oxford, OXI 3RB, Oxford, UK aut NATIONALLICENCE 700 1- Kochian Leon U.S. Plant Soil and Nutrition Laboratory, USDA-ARS, Cornell University, 14853, Ithaca, NY, USA aut NATIONALLICENCE 773 0- Plant and Soil Kluwer Academic Publishers; gopher://gopher.wkap.nl/ 180/1(1996-03-01), 57-66 0032-079X 180:1<57 1996 180 11104 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer