Measurement of the Apoplastic Activity of K+and Cl−in the Leaf Epidermis ofCommelina communisin Relation to Stomatal Activity

Bowling, D. J. F. 1987. Measurement of the apoplastic activity of K+ and Cl− in the leaf epidermis of Commelina communis in relation to stomatal activity.−J. exp. Bot. 38: 1351–1355. Ionic activity of K+ and Cl− in the apoplast of the lower epidermis of the leaf of Commelina communis was measured using ion selective micro-electrodes. Large gradients across the stomatal complex were observed which were related to stomatal aperture. On stomatal closure the activity of K+ and Cl− in the apoplast of the guard cell rose from 3·0 mol m−3 to 100 mol m−3 and 33 mol m−3 respectively. It was concluded that the apoplast is an important pathway for ion transport between the cells.