Potassium co-transport and antiport during the uptake of sucrose and glutamic acid from the xylem vessels

Abstract

Perfusion experiments with excised internodes of tomato (Lycopersicon esculentum cv Moneymaker) showed that the uptake of glutamic acid and sucrose from the xylem vessels is accompanied with coupled proton co-transport and potassium antiport at low pH (<5.5). At high pH (5.5) both proton and potassium co-transport accompany the uptake. The results fit into the proton pump concept.