Abstract
Distinct chemical species of iron were investigated by Mössbauer spectroscopy during iron uptake into cucumber roots grown in unbuffered nutrient solution with or without 57Fe-citrate. Mössbauer spectra of iron deficient roots supplied with 10–500 μM 57Fe-citrate for 30–180 min and 24 h and iron-sufficient ones, were recorded. The roots were analysed for Fe concentration and Fe reductase activity. The Mössbauer parameters in the case of iron-sufficient roots revealed high-spin iron(III) components suggesting the presence of FeIII-carboxylate complexes, hydrous ferric oxides and sulfate–hydroxide containing species. No FeII was detected in these roots. However, iron-deficient roots supplied with 0.5 mM 57FeIII-citrate for 30 min contained significant amount of FeII in a hexaaqua complex form. This is a direct evidence for the Strategy I iron uptake mechanism. Correlation was found between the decrease in Fe reductase activity and the ratio of FeII–FeIII components as the time of iron supply was increased. The data may refer to a higher iron reduction rate as compared to its uptake/reoxidation in the cytoplasm in accordance with the increased reduction rate in iron deficient Strategy I plants.
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Abbreviations
- FRO2:
-
Ferric reductase oxidase 2
- FAD:
-
Flavin adenine dinucleotide
- NADP:
-
Nikotinamid-adenin-dinukleotid-foszfát
- IRT1:
-
Iron-regulated transporter 1
- ZIP:
-
Zinc-regulated transporter
- EDTA:
-
Ethylene diamine tetraacetic acid
- NA:
-
Nicotianamine
- ICP-MS:
-
Inductively coupled plasma mass spectrometry
- BPDS:
-
Bathophenantrolinedisulphonate
- MES:
-
2-(N-morpholino)ethanesulfonic acid
- fw:
-
Fresh weight
- dw:
-
Dry weight
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Acknowledgments
This work was supported by the Hungarian National Science Foundation (OTKA) K62691, K67835, K68135 and NN74045. The authors wish to thank Nicolaus von Wirén for the useful suggestions for the experimental design in completing this work. We thank professor Jean-Marc Greneche for the low temperature Mössbauer measurement.
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Kovács, K., Kuzmann, E., Tatár, E. et al. Investigation of iron pools in cucumber roots by Mössbauer spectroscopy: direct evidence for the Strategy I iron uptake mechanism. Planta 229, 271–278 (2009). https://doi.org/10.1007/s00425-008-0826-x
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DOI: https://doi.org/10.1007/s00425-008-0826-x