Abstract
The action of auxin in the promotion of growth has been suggested in the literature to depend on cell wall acidification. In a former investigation by the present authors the electrochemical balance in auxin-induced proton extrusion was shown to be maintained by potassium net uptake. The present paper reports data demonstrating that the elongation of Avena coleoptile segments is accompanied by an accumulation of malate, which is stoichiometrically correlated with potassium uptake. We concluded that this malate accumulation is required in a mechanism regulating intracellular pH.