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Promoting effect of fusicoccin on Na + efflux in barley roots: evidence for a Na + −H + antiport
Author(s) -
COLOMBO R.,
BONETTI A.,
LADO P.
Publication year - 1979
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1979.tb00082.x
Subject(s) - fusicoccin , efflux , antiporter , chemistry , electrochemical gradient , biophysics , proton , ion transporter , membrane transport , nuclear chemistry , inorganic chemistry , membrane , biochemistry , atpase , enzyme , biology , physics , quantum mechanics
. The effect of fusicoccin (FC) on the K + stimulated Na + efflux in root cells of Na + loaded barley roots was studied. FC (0.02 mM) stimulated Na + efflux in the presence of K + and its effect was synergistic with that of K + , in a similar way as its effect on proton extrusion. Decreasing the pH of the elution medium promoted Na + efflux and partially replaced the effect of FC. As FC is known to increase the electrochemical proton gradient at the plasmalemma level, these results are consistent with the hypothesis that Na + is extruded in exchange for H + . A further support to this view came from the finding that Na + efflux was also promoted by a lipophilic cation, tributylbenzylammonium (TBBA + ), which stimulates H + extrusion and is generally accepted not to enter the cells by means of the same carrier as K + .