Osmotic measurements on stomata


Osmotic measurements on stomatal cells of Commelina communis L.

by MacRobbie E. A. C. (1980)

Enid Anne Campbell MacRobbie, University of Cambridge

in J. Membr. Biol. 53: 189-198. – DOI: 10.1007/BF01868824 –


Observations of aperture changes as sucrose is added to the solution bathing epidermal strips of Commelina communis L. allow calculation of the osmotic changes required to open or close the stomatal pore, for comparison with changes in potassium content.
With “isolated” guard cells, in strips in which all cells other than guard cells have been killed, the internal osmotic changes required are 83 mosmol kg-1 µm-1 below 10µm aperture, 129 mosmol kg-1 µm-1 in the range 10–15 µm, and 180 mosmol kg-1 µm-1 above 15 µm.
For opening against subsidiary cell turgor in addition to guard cell turgor, in intact strips with live subsidiary and epidermal cells, these figures should each be increased by about 33 mosmol kg-1 µm-1. A change in subsidiary cell turgor is magnified in its effects on the water relations of the guard cell by a factor greater than 3.7 for equal changes in the water potential of the two cells, or greater than 4.7 at constant volume of the guard cell.

Published by

Willem Van Cotthem

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

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s