Effects of periodic- and transient-osmotic stress on electric potentials in bean roots

Intact bean (Phaseolus mungo) roots were subjected to periodic- and transient-osmotic stress by treatment with a solution of low water potential Ψ°. Both the intracellular potential, E, and the extracellular potential, V, were measured with a multimicrochamber system that combined intracellular microelectrodes and external electrodes. In elongating regions, Ψ° simultaneously affected potentials E and V. The response of E to Ψ° could be presented by a transfer function that included dead time and first order elements. These elements were consistent with the emergence of an electromotive force, produced by respiration, between the cortex and the stele in the elongating region.