Availability of chloride affects the balance between KCl and potassium malate in guard cells

Availability of chloride affects the balance between potassium chloride and potassium malate in guard cells of Vicia faba L.

by Raschke K., Schnabl H. (1978)

Klaus Raschke, Heide Schnabl,


In Plant Physiol. 62: 84–87 – DOI: https://doi.org/10.1104/pp.62.1.84



Electron probe microanalysis for K and Cl and enzymic determination of malate were performed on epidermal strips of Vicia faba L. which had been incubated with 0.1 equivalent of K+ per liter in the absence or presence of Cl.

In the absence of Cl, iminodiacetate, a presumed impermeant zwitterion, served as anion. With no Cl in the medium, 91% of the K+ imported into the guard cells during stomatal opening was neutralized by malate production; import of Cl (presumably from the rest of the epidermal tissue) contributed 6%.

In the presence of Cl, 50% of the necessary negative charges were provided by malate synthesis, 45% by Cl import.

Stomatal opening was not obviously affected by the chloride concentration in the incubation medium, but malate production declined roughly linearly with the logarithm of [Cl] between 10−5 and 10−1 equivalent per liter.

Published by

Willem Van Cotthem

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

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