, Volume 244, Issue 1, pp 167–179 | Cite as

Revisiting the iron pools in cucumber roots: identification and localization

  • Krisztina Kovács
  • Jiří Pechoušek
  • Libor Machala
  • Radek Zbořil
  • Zoltán Klencsár
  • Ádám Solti
  • Brigitta Tóth
  • Brigitta Müller
  • Hong Diep Pham
  • Zoltán Kristóf
  • Ferenc Fodor
Original Article


Main conclusion

Fe deficiency responses in Strategy I causes a shift from the formation of partially removable hydrous ferric oxide on the root surface to the accumulation of Fe-citrate in the xylem.

Iron may accumulate in various chemical forms during its uptake and assimilation in roots. The permanent and transient Fe microenvironments formed during these processes in cucumber which takes up Fe in a reduction based process (Strategy I) have been investigated. The identification of Fe microenvironments was carried out with 57Fe Mössbauer spectroscopy and immunoblotting, whereas reductive washing and high-resolution microscopy was applied for the localization. In plants supplied with 57FeIII-citrate, a transient presence of Fe-carboxylates in removable forms and the accumulation of partly removable, amorphous hydrous ferric oxide/hydroxyde have been identified in the apoplast and on the root surface, respectively. The latter may at least partly be the consequence of bacterial activity at the root surface. Ferritin accumulation did not occur at optimal Fe supply. Under Fe deficiency, highly soluble ferrous hexaaqua complex is transiently formed along with the accumulation of Fe-carboxylates, likely Fe-citrate. As 57Fe-citrate is non-removable from the root samples of Fe deficient plants, the major site of accumulation is suggested to be the root xylem. Reductive washing results in another ferrous microenvironment remaining in the root apoplast, the FeII-bipyridyl complex, which accounts for ~30 % of the total Fe content of the root samples treated for 10 min and rinsed with CaSO4 solution. When 57FeIII-EDTA or 57FeIII-EDDHA was applied as Fe-source higher soluble ferrous Fe accumulation was accompanied by a lower total Fe content, confirming that chelates are more efficient in maintaining soluble Fe in the medium while less stable natural complexes as Fe-citrate may perform better in Fe accumulation.


Cucumis sativus L. Ferritin Hydrous ferric oxides Iron uptake Mössbauer spectroscopy 









Electron energy loss spectroscopy





The authors wish to thank Frits Bienfait for the discussion on the bypridyl method. This work was supported by the Hungarian National Science Fund grants National Research, Development and Innovation Office—NKFIH PD 111979, PD 112047 and K 115913. The authors gratefully acknowledge the support by the project LO1305 of the Ministry of Education, Youth and Sports of the Czech Republic. This work (Á.S.) was also supported by the Bolyai János Research Scholarship of the Hungarian Academy of Sciences (BO/00207/15/4).

Supplementary material

425_2016_2502_MOESM1_ESM.pdf (326 kb)
Supplementary material 1 (PDF 326 kb)
425_2016_2502_MOESM2_ESM.pdf (29 kb)
Supplementary material 2 (PDF 28 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Krisztina Kovács
    • 1
  • Jiří Pechoušek
    • 2
  • Libor Machala
    • 2
  • Radek Zbořil
    • 2
  • Zoltán Klencsár
    • 3
  • Ádám Solti
    • 4
  • Brigitta Tóth
    • 5
  • Brigitta Müller
    • 4
  • Hong Diep Pham
    • 4
  • Zoltán Kristóf
    • 6
  • Ferenc Fodor
    • 4
  1. 1.Institute of ChemistryEötvös Loránd UniversityBudapestHungary
  2. 2.Regional Centre of Advanced Technologies and Materials, Departments of Experimental Physics and Physical Chemistry, Faculty of SciencePalacký University in OlomoucOlomoucCzech Republic
  3. 3.Institute of Materials and Environmental Chemistry, Research Centre for Natural SciencesHungarian Academy of SciencesBudapestHungary
  4. 4.Department of Plant Physiology and Molecular Plant Biology, Institute of BiologyEötvös Loránd UniversityBudapestHungary
  5. 5.Department of Botany, Crop Physiology and Biotechnology, Institute of Plant Sciences, Faculty of Agricultural and Food Sciences and Environmental ManagementUniversity of DebrecenDebrecenHungary
  6. 6.Department of Plant Anatomy, Institute of BiologyEötvös Loránd UniversityBudapestHungary

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