Intracellular concentrations of potassium, chloride, and protons during differentiation of tobacco male gametophyte

Changes in intracellular pH, K+ and Cl- concentrations were measured in pollen grains, anther loculi, and whole anthers during in vivo differentiation of male gametophyte of Nicotiana tabacum L. The effects of extracellular K+ and Cl- on intracellular pH regulation were also studied during development of pollen grains in vitro. Ion-selective electrodes and X-ray microanalysis were used to measure ion concentrations, and microfluorometry was used to measure pH. The intracellular pH and [K+] decreased at the mid- and late binucleate stages of pollen grain development, while [Cl-] increased. At the same stages, K+ and Cl- concentrations in locular liquid were found to increase. The intracellular pH in pollen grains, isolated at the mid-binucleate stage, decreased during in vitro development in the medium containing 50 mM KCl. It was suggested that changes in ionic composition of the external medium can regulate the intracellular pH during development of pollen grain in vivo.