Net fluxes of H+ and Ca2+ were measured in the mesophyll tissue of broad bean (Vicia faba L.) leaves and in protoplasts derived from these cells. NaCl at 90 mm enhanced H+ extrusion in both protoplasts and tissue, but in different ways. Proton extrusion was inhibited by vanadate, suggesting the involvement of the plasma membrane H+-ATPase in cell responses to salinity. There was virtually no effect of NaCl on the net Ca2+ flux in protoplasts, while in the tissue a large transient Ca2+ efflux followed the salt treatment. Salt-induced Ca2+ efflux was essentially independent of external Ca2+ concentrations in the range 0.1 to 10 mm. Also, Ca2+ flux responses were 'saturated' above 50 mM NaCl. It is suggested that almost all the measured Ca2+ flux originates from Na+/Ca2+ and H+/Ca2+ ion exchange in the cell wall. This conclusion was supported by the results of modelling cation exchange in the cell wall. (C) 2000 Annals of Botany Company.
History
Publication title
Annals of Botany
Volume
85
Issue
5
Pagination
681-686
ISSN
0305-7364
Department/School
Physics, Agriculture and Food Systems
Publisher
Academic Press
Publication status
Published
Place of publication
London, England
Socio-economic Objectives
280111 Expanding knowledge in the environmental sciences