Influence of Boron on the Membrane Potential in <i>Elodea densa</i> and <i>Helianthus annuus</i> Roots and H⁺ Extrusion of Suspension Cultured <i>Daucus carota</i> Cells

Abstract

When following the membrane potential of Elodea densa leaf cells during a dark-light regime and analysing the different phases of the cycle, the pattern under boron deficiency resembled the one reported to occur after 3-(3,4-dichlorophenyl)-1,1-dimethylurea application. The potential in the dark slowly decreased when transferring Elodea densa leaflets and Helianthus annuus roots to a B-free medium and increased in the same way after B was added again. Addition of vanadate to inhibit plasmalemma ATPases in part mimicked the effects of B deficiency. It is suggested that B directly or indirectly affects the formation of a proton gradient. The effect of B on proton secretion was observed in various experiments with Daucus carota cell cultures. The results are discussed with respect to the possible involvement of B in membrane function and transport processes.