Effects of external potassium chloride on electrical properties and potassium rubidium 86 transport in the elongating region of intact phaseolus mungo roots
Ishikawa, H.; Matsuura, K.; Yamamura, S.; Ohta, E.; Sakata, M.
Plant and Cell Physiology 25(3): 359-366
Two simultaneous measurements, extracellular potential V and K+ (86Rb) transport, and the intracellular potential of cortical cell E and potential V, were used to study the effects of external KCl on 2-day-old bean roots. High, external KCl concentrations (> 10 mM) markedly enhanced K+ loss from tissues in the elongating region to the external solution and induced depolarization of the membrane potential difference (PD = V-E). When Phaseolus roots were returned to a solution with a lower concentration of K+, the K+ loss and the potential difference, PD, were restored to their previous values. K+ transport from other parts of the root to the elongating region did not recover, and the potential E increased. Treatment of Phaseolus roots with a high external K+ concentration inhibits K+ translocation through the stele to the elongating cortical cells and is dependent on depolarization of the intracellular potential.