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Characteristics of cadmium uptake in two contrasting ecotypes of the hyperaccumulator Thlaspi caerulescens.
- Source :
-
Journal of experimental botany [J Exp Bot] 2002 Mar; Vol. 53 (368), pp. 535-43. - Publication Year :
- 2002
-
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 degrees C was assumed to represent mainly apoplastic binding in the roots, whereas the difference in uptake between 22 degrees C and 2 degrees 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 V(max) of 143 nmol g(-1) root FW h(-1) and a K(m) of 0.45 microM. 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.
- Subjects :
- Binding Sites
Brassicaceae drug effects
Cadmium pharmacology
Cadmium Radioisotopes
Calcium pharmacology
Calcium Channel Blockers pharmacology
Cations, Divalent pharmacology
Cell Wall physiology
Kinetics
Plant Roots drug effects
Species Specificity
Verapamil pharmacology
Zinc pharmacology
Zinc Radioisotopes
Brassicaceae physiology
Cadmium metabolism
Plant Roots physiology
Zinc metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0022-0957
- Volume :
- 53
- Issue :
- 368
- Database :
- MEDLINE
- Journal :
- Journal of experimental botany
- Publication Type :
- Academic Journal
- Accession number :
- 11847252
- Full Text :
- https://doi.org/10.1093/jexbot/53.368.535