Plant and Soil

, Volume 114, Issue 2, pp 217–226 | Cite as

Mobilization of iron and other micronutrient cations from a calcareous soil by plant-borne, microbial, and synthetic metal chelators

  • M. Treeby
  • H. Marschner
  • V. Römheld


Mobilization of Fe, Zn, Cu, and Mn by various chelators from a calcareous soil was measured using a simple dialysis tube/complexing resin system. Root exudates from Fe-deficient barley increased the concentrations of all four metals in solution by, on average, a factor of 20, and the addition of complexing resin as a sink for heavy metal cations forced steady state solution concentrations to be reached sooner. Root exudates mobilized increasing amounts of the various micronutrients in the following order: Cu<Fe<Zn<Mn. Phytosiderophores isolated from root exudates of Fe-deficient barley mobilized similar amounts of Cu and Zn but somewhat more Fe and considerably more Mn than crude exudate. The synthetic chelators EDDHA and DTPA showed low specificity in micronutrient mobilization, but the microbial siderophore Desferal was relatively more specific, preferentially mobilizing Fe and Mn. The data indicates that phytosiderophores are capable of increasing the amount of complexed cations in solution. Despite their lack of specificity, phytosiderophores were just as effective as Desferal increasing the availability of Fe. Thus, phytosiderophores, as plant-borne chelators, are certainly of significance for the Fe nutrition of cereals grown in calcareous soils.

Key words

barley chelators copper iron manganese mobilization phytosiderophores root exudates siderophores zinc 


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  1. Amberger A, Gutser R and Wünsch A 1982 Iron chlorosis induced by higher copper and manganese supply. J Plant Nutr. 5, 715–720.Google Scholar
  2. Awad F, Römheld V and Marschner H 1988 Mobilization of ferric iron from a calcareous soil by plant-borne chelators (phytosiderophores). J. Plant Nutr. 11, 701–713.Google Scholar
  3. Barrett-Lennard E G, Marschner H and Römheld V 1983 Mechanism of short term FeIII reduction by roots. Evidence against the role of secreted reductants. Plant Physiol. 73, 893–898.Google Scholar
  4. Brown J C and Tiffin L O 1962 Zinc deficiency and iron chlorosis dependent on the plant species and nutrient-element balance in Tulare clay. Agron. J. 54, 356–358.Google Scholar
  5. Chaney R L, Brown J C and Tiffin L O 1972 Obligatory reduction of ferric chelates in iron uptake by soybeans. Plant Physiol. 50, 208–213.Google Scholar
  6. Clark R B, Pier P A, Knudsen D and Maranville J W 1981 Effects of trace element deficiencies and excesses on mineral nutrients in sorghum. J. Plant Nutr. 3, 357–374.Google Scholar
  7. Crowley D E, Reid C P P and Szanislo P J 1987 Microbial siderophores as iron sources for plants.In Iron Transport in Microbes, Plants and Animals. Eds. G Winkelmann, D van der Helm and J B Neilands. pp 375–386. VCH, Weinheim.Google Scholar
  8. Graham R D 1981 Absorption of copper by plant roots.In Copper in Soils and Plants. Eds. J F Loneragan, A D Robson and R D Graham. pp 141–163. Academic Press, London.Google Scholar
  9. Lim C H and Jackson M K 1982 Dissolution for total elemental analysis.In Methods of Soil Analysis, Part 2. Chemical and Microbiological Properties. Eds. A L Page, R H Miller and D R Keeney. pp 1–12, Agronomy Monograph no. 9 (2nd Edition), Am Soc Agron and Soil Soc Am, Madison, Wisc.Google Scholar
  10. Lindsay W L 1974 Role of chelation in micronutrient availability.In The Plant Root and Its Environment. Ed. C W Carson. pp 507–524. University Press of Virginia, Chlarlottsville.Google Scholar
  11. Lindsay W L 1979 Chemical Equilibria in Soils. John Wiley and Sons, New York.Google Scholar
  12. Lindsay W L and Norvell W A 1978 Development of a DTPA soil test for zinc, iron, manganese and copper. Soil Sci. Soc. Am. J. 42, 421–428.Google Scholar
  13. Linehan D J, Sinclair A H and Mitchell M C 1985 Mobilisation of Cu, Mn and Zn in the soil solutions of barley rhizospheres. Plant and Soil 86, 147–149.CrossRefGoogle Scholar
  14. Marschner H 1986 Mineral Nutrition of Higher Plants. Academic Press, London.Google Scholar
  15. Marschner H, Römheld V and Kissel M 1987 Localization of phytosiderophore release and of iron uptake along intact barley roots. Physiol. Plant. 71, 157–162.Google Scholar
  16. Merckx R, van Ginkel J H, Sinnaeve J and Cremers A 1986 Plant-induced changes in the rhizosphere of maize and wheat. II. Complexation of cobalt, zinc and manganese in the rhizosphere of maize and wheat. Plant and Soil 96, 95–107.Google Scholar
  17. Mori S, Nishizawa N, Kawai S, Sata Y and Takagi 1987 Dynamic state of mugineic acid and analogous phytosiderphores in Fe-deficient barley. J Plant Nutr. 10, 1003–1011.Google Scholar
  18. Nomoto R, Sugiura Y and Takagi S 1987 Mugineic acids, studies on phytosiderophores.In Iron Transport in Microbes, Plants and Animals. Eds. G Winkelmann, D van der Helm and J B Neilands. pp 401–425. VCH, Weinheim.Google Scholar
  19. Nielsen N E 1976 The effect of plants on the copper concentration in the soil solution. Plant and Soil 45, 679–687.Google Scholar
  20. Olsen R A, Bennett J H, Blume J C and Brown J C 1981 Chemical aspects of the Fe stress response mechanism in tomatoes. J. Plant Nutr. 3, 905–921.Google Scholar
  21. Reid R K, Reid C P P and Szaniszlo P J 1985 Effects of synthetic and microbially produced chelates on the diffusion of iron and phsophorus to a simulated root in soil. Biol. Fert. Soils 1, 45–52.CrossRefGoogle Scholar
  22. Römheld V 1987 Different strategies for iron acquisition in higher plants. Physiol. Plant. 70, 231–234.Google Scholar
  23. Römheld V and Marschner H 1983 Mechanism of iron uptake by peanut plants. I. FeIII reduction, chelate splitting, and release of phenolics. Plant Physiol. 71, 949–954.Google Scholar
  24. Römheld V and Marschner H 1986 Evidence for a specific uptake system for iron phytosiderophores in roots of grasses. Plant Physiol. 80, 175–180.Google Scholar
  25. Sinha M K and Prasad B 1977 Effect of chelating agents on the kinetics of diffusion of zinc to a simulated root system and its uptake by wheat. Plant and Soil 48, 599–612.CrossRefGoogle Scholar
  26. Takagi S 1976 Naturally occurring iron-chelating compounds in oat- and rice-root washing. I. Activity measurement and preliminary characterization. Soil Sci. Plant Nutr. 22, 423–433.Google Scholar

Copyright information

© Kluwer Academic Publishers 1989

Authors and Affiliations

  • M. Treeby
    • 1
  • H. Marschner
    • 1
  • V. Römheld
    • 1
  1. 1.Institut für PflanzenernährungUniversität HohenheimStuttgart 70FRG

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