Differential expression and regulation of iron-regulated metal transporters in Arabidopsis halleri and Arabidopsis thaliana – the role in zinc tolerance

Authors

  • Varanavasiappan Shanmugam,

    1. Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan, 11529
    2. Molecular and Biological Agricultural Sciences, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, Taiwan, 11529
    3. Graduate Institute of Biotechnology and Department of Life Sciences, National Chung-Hsing University, Taichung, Taiwan, 402
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    • These authors contributed equally to this work.

  • Jing-Chi Lo,

    1. Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan, 11529
    2. Institute of Plant Biology, National Taiwan University, Taipei, Taiwan 10617
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    • These authors contributed equally to this work.

  • Chia-Lin Wu,

    1. Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan, 11529
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  • Shan-Li Wang,

    1. Department of Soil and Environmental Sciences, National Chung-Hsing University, Taichung, Taiwan 402
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  • Chong-Cheong Lai,

    1. Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan, 11529
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  • Erin L. Connolly,

    1. Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
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  • Jing-Ling Huang,

    1. Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan, 11529
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  • Kuo-Chen Yeh

    1. Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan, 11529
    2. Molecular and Biological Agricultural Sciences, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, Taiwan, 11529
    3. Graduate Institute of Biotechnology and Department of Life Sciences, National Chung-Hsing University, Taichung, Taiwan, 402
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Author for correspondence:
Kuo-Chen Yeh
Tel: +886 2 2787 2056
Email: kcyeh@gate.sinica.edu.tw

Summary

  • To avoid zinc (Zn) toxicity, plants have developed a Zn homeostasis mechanism to cope with Zn excess in the surrounding soil. In this report, we uncovered the difference of a cross-homeostasis system between iron (Fe) and Zn in dealing with Zn excess in the Zn hyperaccumulator Arabidopsis halleri ssp. gemmifera and nonhyperaccumulator Arabidopsis thaliana.
  • Arabidopsis halleri shows low expression of the Fe acquisition and deficiency response-related genes IRT1 and IRT2 compared with A. thaliana. In A. thaliana, lowering the expression of IRT1 and IRT2 through the addition of excess Fe to the medium increases Zn tolerance.
  • Excess Zn induces significant Fe deficiency in A. thaliana and reduces Fe accumulation in shoots. By contrast, the accumulation of Fe in shoots of A. halleri was stable under various Zn treatments. Root ferric chelate reductase (FRO) activity and expression of FIT are low in A. halleri compared with A. thaliana. Overexpressing a ZIP family member IRT3 in irt1-1, rescues the Fe-deficient phenotype.
  • A fine-tuned Fe homeostasis mechanism in A. halleri maintains optimum Fe level by Zn-regulated ZIP transporters and prevents high Zn uptake through Fe-regulated metal transporters, and in part be responsible for Zn tolerance.

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