Regulation and mechanism of potassium release from barley roots: An in planta42K analysis

Abstract

Summary: Potassium (K+) flux into plant cells is a well-characterized ion transport phenomenon. By contrast, little is known about the mechanisms and regulation of K+ flux from the cell. Here, we present a radioisotopic analysis of K+ fluxes from roots of intact barley (Hordeum vulgare), in the context of recent discoveries in the molecular biology and electrophysiology of this process. Plants were labelled with 42K+, and kinetics of its release from roots were monitored at low (0.1 mM) or high (1.0 mM) external K concentration, [K+]ext, and with the application of channel modulators and nutrient shifts..At 0.1 (but not 1.0) mM [K+], where K+ efflux is thought to be mediated by K+-outward-re..