Potassium and sucrose in stomata osmoregulation


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Heirloom Fava bean Broad Windsor Seeds

Central roles for potassium and sucrose in guard-cell osmoregulation.

by Talbott L. D., Zeiger E. (1996)

L. D. Talbott

Eduardo Zeiger

in Plant Physiol. 111, 1051–1057 -PMID: 12226347 PMCID: PMC160980 – DOI: https://doi.org/10.1104/pp.111.4.1051

PubMed Abstract | Google Scholar



Osmoregulation in guard cells of intact, attached Vicia faba leaves grown under growth chamber and greenhouse conditions was studied over a daily light cycle of stomatal movements.

Under both growth conditions guard cells had two distinct osmoregulatory phases. In the first (morning) phase, opening was correlated with K+ uptake and, to a lesser extent, sucrose accumulation. In the second (afternoon) phase, in which apertures were maximal, K+ content declined and sucrose became the dominant osmoticum.

Reopening of the stomata after a CO2-induced closure was accompanied by accumulation of either K+ or sucrose, depending on the time of day, indicating that a single environmental signal may use multiple osmoregulatory pathways.

Malate accumulation, correlated with K+ uptake, was detected under growth chamber but not greenhouse conditions, whereas Cl- was the main K+ counterion in the greenhouse.

These results indicate that guard-cell osmoregulation in the intact leaf depends on at least two different osmoregulatory pathways, K+ transport and sucrose metabolism. Furthermore, the relative importance of the K+ counterions malate and Cl- appears to be environment-dependent.


Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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