Transient light-induced changes in ion channel and proton pump activities in the plasma membrane of tobacco mesophyll protoplasts

• Published in: Journal of experimental botany Vol. 48; no. 314; pp. 1623 - 1630
• Main Authors: Blom-Zandstra, Margaretha, Koot, Hans, van Hattum, Joke, Vogelzang, Sake A.
• Format: Journal Article
• Language: English
• Published: Oxford OXFORD UNIVERSITY PRESS 01.09.1997; Oxford University Press
• Subjects: Biological and medical sciences; Cell and Molecular Biology, Biochemistry and Molecular Physiology; Cell membranes; Cell physiology; Electric current; Electric potential; Fundamental and applied biological sciences. Psychology; Instituut voor Agrobiologisch en Bodemvruchtbaarheidsonderzoek; Mesophyll; Plant cells; Plant physiology and development; Plasma currents; Plasma membrane and permeation; Proton pumps; Protons; Protoplasts; Pumps; Research Institute for Agrobiology and Soil Fertility; Enzyme; H; transporting ATP synthase; Nicotiana tabacum; Regulation(control); Dicotyledones; Light; Protoplast; Angiospermae; Hydrolases; Isolation; Spermatophyta; Solanaceae; Membrane potential; Membrane channel; Photosynthesis; Potassium
• ISSN: 0022-0957; 1460-2431; 1460-2431
• DOI: 10.1093/jexbot/48.314.1623

Rapid, transient changes of the membrane potential upon light transitions are generally observed in microelectrode studies. In a patch-clamp study similar responses to light transitions were found in current clamp. Corresponding with the changes of membrane potential, light-induced current changes in voltage clamp were observed. This paper evaluates the involvement of outward rectifying conductances and plasma membrane bound H+-ATPases (proton pump) to these light responses in mesophyll protoplasts of Nicotiana tabacum L. The contribution of K+-channels to these responses, could be minimized by variation of the holding potential or addition of the K+-channel blocker verapamil. It was concluded that light transitions modulate both proton pump and K+-channel activity. Effects of light on membrane current were not observed in root cells and chlorophyll-deficient cells, suggesting that the response requires photosynthetic activity. However, blockers of photosystems I and II did not affect current changes.