Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/27319
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Type: Journal article
Title: Characteristics of cadmium uptake in two contrasting ecotypes of the hyperaccumulator Thlaspi caerulescens
Author: Zhao, F.
Hamon, R.
Lombi, E.
McLaughlin, M.
McGrath, S.
Citation: Journal of Experimental Botany, 2002; 53(368):535-543
Publisher: Oxford Univ Press
Issue Date: 2002
ISSN: 0022-0957
1460-2431
Statement of
Responsibility: 
Fang-Jie Zhao, Rebecca E. Hamon, Enzo Lombi, Mike J. McLaughlin and Steve P. McGrath
Abstract: Uptake of Cd and Zn by intact seedlings of two contrasting ecotypes of the hyperaccumulator Thlaspi caerulescens was characterized using radioactive tracers. Uptake of Cd and Zn at 2 °C was assumed to represent mainly apoplastic binding in the roots, whereas the difference in uptake between 22 °C and 2 °C represented metabolically dependent influx. There was no significant difference between the two ecotypes in the apoplastic binding of Cd or Zn. Metabolically dependent uptake of Cd was 4.5-fold higher in the high Cd-accumulating ecotype, Ganges, than in the low Cd-accumulating ecotype, Prayon. By contrast, there was only a 1.5-fold difference in the Zn uptake between the two ecotypes. For the Ganges ecotype, Cd uptake could be described by Michaelis–Menten kinetics with a Vmax of 143 nmol g-1 root FW h-1 and a Km of 0.45 µM. Uptake of Cd by the Ganges ecotype was not inhibited by La, Zn, Cu, Co, Mn, Ni or Fe(II), and neither by increasing the Ca concentration. By contrast, addition of La, Zn or Mn, or increasing the Ca concentration in the uptake solution decreased Cd uptake by Prayon. Uptake of Ca was larger in Prayon than in Ganges. The results suggest that Cd uptake by the low Cd-accumulating ecotype (Prayon) may be mediated partly via Ca channels or transporters for Zn and Mn. By contrast, there may exist a highly selective Cd transport system in the root cell membranes of the high Cd-accumulating ecotype (Ganges) of T. caerulescens.
Keywords: Cell Wall; Brassicaceae; Plant Roots; Cations, Divalent; Calcium; Cadmium; Zinc; Cadmium Radioisotopes; Zinc Radioisotopes; Verapamil; Calcium Channel Blockers; Species Specificity; Binding Sites; Kinetics
Description: Copyright © 2002 Oxford University Press
RMID: 0020022109
DOI: 10.1093/jexbot/53.368.535
Published version: http://jxb.oxfordjournals.org/cgi/content/abstract/53/368/535
Appears in Collections:Soil and Land Systems publications
Environment Institute publications

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