Guard cells elongation and stomatal movement


Guard cells elongate: relationship of volume and surface area during stomatal movement.

by Meckel T., Gall L., Semrau S., Homann U., Thiel G. (2007)

Tobias Meckel,* Lars Gall, Stefan Semrau,* Ulrike Homann, Gerhard Thiel

Tobias Meckel, BiologieTechnische Universität Darmstadt
Lars Gall, Darmstadt University of Technology
Stefan Semrau, Leiden Institute of Physics, Cell Observatory
Ulrike Homann, Biologie Technische Universität Darmstadt


Gerhard Thiel, Biologie – Technische Universität Darmstadt
*Leiden Institute of Physics, University of Leiden, 2333 CA Leiden, The Netherlands; and Department of Botany, Darmstadt University of Technology, 4287 Darmstadt, Germany

in Biophysical journal 92, 1072-1080. – doi:  10.1529/biophysj.106.092734 –


Stomata in the epidermis of photosynthetically active plant organs are formed by pairs of guard cells, which create a pore, to facilitate CO2 and water exchange with the environment.

To control this gas exchange, guard cells actively change their volume and, consequently, surface area to alter the aperture of the stomatal pore. Due to the limited elasticity of the plasma membrane, such changes in surface area require an exocytic addition or endocytic retrieval of membrane during stomatal movement.

Using confocal microscopic data, we have reconstructed detailed three-dimensional models of open and closed stomata to precisely quantify the necessary area to be exo- and endocytosed by the guard cells. Images were obtained under a strong emphasis on a precise calibration of the method and by avoiding unphysiological osmotical imbalance, and hence osmocytosis.

The data reveal that guard cells of Vicia faba L., whose aperture increases by 111.89 ± 22.39%, increase in volume and surface area by 24.82 ± 6.26% and 14.99 ± 2.62%, respectively. In addition, the precise volume to surface area relationship allows quantitative modeling of the three-dimensional changes. While the major volume change is caused by a slight increase in the cross section of the cells, an elongation of the guard cells achieves the main aperture change.


Published by

Willem Van Cotthem

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

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