Proton-Chloride Symport in Barley Roots

An increase in the acidity of the incubation medium from pH 6 5 to pH 4.0 increased Cl- flux into ATP-depleted Hordeum vulgare L roots more than three times This ΔpH-dependent Cl− flux was inhibited by p-chloromercuriphenyl sulphonic acid. The effect of pH on Cl- influx was eliminated when the pH gradient was dissipated by addition of salts of permeable weak acids, and in K-loaded roots in the presence of a protonophore together with valinomycin The results support the assumption that a H+-Cl−symport system is present in barley root cells