Measurement of differential Na effulx from apical and bulk root zones of intact barley and Arabidopsis plants

Abstract

Rapid sodium cycling across the plasma membrane of root cells is widely thought to be associated with Na+ toxicity in plants. However, the effulx component of this cycling is not well understood. Effulx of Na+ from root cells is believed to be mediated by Salt Overly-Sensitive-1, although expression of this Na+/H+ antiporter has been localized to the vascular tissue and root meristem. Here, we used a chambered cuvette system in which the distal root of intact salinized barley and Arabidopsis thaliana plants (wild-type and sos1) were isolated from the bulk of the root by a silicone-acrylic barrier, so that we could compare patterns of 24Na+ effulx in these two regions of root. In barley, stea..