Senescence-induced iron mobilization in source leaves of barley (Hordeum vulgare) plants

Authors

  • Rongli Shi,

    1. Molecular Plant Nutrition, Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466 Gatersleben, Germany
    2. Department of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China
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  • Günther Weber,

    1. Leibniz-Institut für Analytische Wissenschaften – ISAS – e.V., Bunsen-Kirchhoff-Str 11, 44139 Dortmund, Germany
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  • Jessica Köster,

    1. Leibniz-Institut für Analytische Wissenschaften – ISAS – e.V., Bunsen-Kirchhoff-Str 11, 44139 Dortmund, Germany
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  • Mohammad Reza-Hajirezaei,

    1. Molecular Plant Nutrition, Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466 Gatersleben, Germany
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  • Chunqin Zou,

    1. Department of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China
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  • Fusuo Zhang,

    1. Department of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China
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  • Nicolaus von Wirén

    1. Molecular Plant Nutrition, Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466 Gatersleben, Germany
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Author for correspondence:
Nicolaus von Wirén
Tel: +49 39482 5602
Email: vonwiren@ipk-gatersleben.de

Summary

  • Retranslocation of iron (Fe) from source leaves to sinks requires soluble Fe binding forms. As much of the Fe is protein-bound and associated with the leaf nitrogen (N) status, we investigated the role of N in Fe mobilization and retranslocation under N deficiency- vs dark-induced leaf senescence.
  • By excluding Fe retranslocation from the apoplastic root pool, Fe concentrations in source and sink leaves from hydroponically grown barley (Hordeum vulgare) plants were determined in parallel with the concentrations of potential Fe chelators and the expression of genes involved in phytosiderophore biosynthesis.
  • N supply showed opposing effects on Fe pools in source leaves, inhibiting Fe export out of source leaves under N sufficiency but stimulating Fe export from source leaves under N deficiency, which partially alleviated Fe deficiency-induced chlorosis. Both triggers of leaf senescence, shading and N deficiency, enhanced NICOTIANAMINE SYNTHASE2 gene expression, soluble Fe pools in source leaves, and phytosiderophore and citrate rather than nicotianamine concentrations.
  • These results indicate that Fe mobilization within senescing leaves is independent of a concomitant N sink in young leaves and that phytosiderophores enhance Fe solubility in senescing source leaves, favoring subsequent Fe retranslocation.

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