Characterization of Cd translocation and identification of the Cd form in xylem sap of the Cd-hyperaccumulator Arabidopsis halleri

Daisei Ueno, Takashi Iwashita, Fang Jie Zhao, Jian Feng Ma

    Research output: Contribution to journalArticlepeer-review

    123 Citations (Scopus)

    Abstract

    Arabidopsis halleri is a Cd hyperaccumulator; however, the mechanisms involved in the root to shoot translocation of Cd are not well understood. In this study, we characterized Cd transfer from the root medium to xylem in this species. Arabidopsis halleri accumulated 1,500 mg kg-1 Cd in the shoot without growth inhibition. A time-course experiment showed that the release of Cd into the xylem was very rapid; by 2 h exposure to Cd, Cd concentration in the xylem sap was 5-fold higher than that in the external solution. The concentration of Cd in the xylem sap increased linearly with increasing Cd concentration in the external solution. Cd transfer to the xylem was completely inhibited by the metabolic inhibitor carbonyl cyanide 3-chlorophenylhydrazone (CCCP). Cd concentration in the xylem sap was decreased by increasing the concentration of external Zn, but enhanced by Fe deficiency treatment. Analysis with 113Cd-nuclear magnetic resonance (NMR) showed that the chemical shift of 113Cd in the xylem sap was the same as that of Cd(NO3)2. Metal speciation with Geochem-PC also showed that Cd occurred mainly in the free ionic form in the xylem sap. These results suggest that Cd transfer from the root medium to the xylem in A. halleri is an energy-dependent process that is partly shared with Zn and/or Fe transport. Furthermore, Cd is translocated from roots to shoots in inorganic forms.

    Original languageEnglish
    Pages (from-to)540-548
    Number of pages9
    JournalPlant and Cell Physiology
    Volume49
    Issue number4
    DOIs
    Publication statusPublished - Apr 2008

    Keywords

    • Arabidopsis halleri
    • Cd
    • Chemical form
    • Hyperaccumulator
    • Xylem sap
    • Zn

    ASJC Scopus subject areas

    • Physiology
    • Plant Science
    • Cell Biology

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