Electronic Resource
Oxford, UK
:
Blackwell Publishing Ltd
Plant, cell & environment
2 (1979), S. 0
ISSN:
1365-3040
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Abstract Absorption of copper and manganese by sunflower roots from solution cultures of varying composition was followed by measuring the concentrations of the metals appearing in whole roots, root cell sap and xylem exudate. Total copper in the fibrous roots was linearly related to the concentration of copper in the external solution but the concentration of copper released to the xylem exudate was buffered somewhat against the changes made externally. No such buffering was observed for managenese. A copper-sensitive electrode, responsive only to free cupric ions was used in conjunction with total copper analysis by atomic absorption spectrophotometry to show that little of the copper (usually 〈 1%) existed as a free ion in any phase of the system. Copper in the xylem exudate may be strongly complexed. An electron paramagnetic resonance spectrum of the xylem exudate indicated that manganese probably was a free divalent ion. Calculation of the electrochemical potential gradient for free cupric ions showed that no special metabolically-linked mechanism need be postulated to account for absorption of copper (or manganese) other than that necessary to maintain the transmembrane potential.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-3040.1979.tb00784.x
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