Indoleacetic acid stimulation of phosphorylation and bicarbonate fixation by chloroplast preparations in light

摘要

The rate of phosphorylation in illuminated chloroplast preparations from spinach, Swiss chard, orAcetabularia mediterraneawas increased by physiological concentrations of indoleacetic acid (IAA), optimum effect being obtained at 10minus;7ensp;M. Treated chloroplasts gave an increased P/2eratio, suggesting a greater degree of coupling between electron transport and ATP synthesis. Five minutes after incubation the effect of the hormone was already noticeable. During prolonged illumination the effect of IAA was greatly magnified, raising the phosphorylation rate more than threefold over the control rate. Stimulation of14C-bicarbonate fixation was also observed in the presence of the same levels of IAA.