High respiratory activity of stomata protoplasts


Photo credit: Google

Vicia faba

High respiratory activity of guard cell protoplasts from Vicia faba L.

by Shimazaki K.-I., Gotow K., Sakaki T., Kondo N. (1983)




in Plant Cell Physiol 24: 1049-1056 – DOI: https://doi.org/10.1093/oxfordjournals.pcp.a076607 –

Google Scholar



The rate of O2 uptake was about 29 times higher in guard cell protoplasts (GCPs) than in mesophyll protoplasts (MGPs) on a Chi basis. The O2 uptake was inhibited by respiratory inhibitors, but stimulated by respiratory uncouplers.

On a Chi basis, the activities of Cyt c oxidase and NADH-Cyt c reductase, mitochondrial enzymes, were about 27 and 35 times higher in GCPs than in MCPs. On a Chi basis, the ATP content was about 9 times higher in GCPs. The amount of ATP in GCPs was decreased by respiratory inhibitors, an energy transfer inhibitor, and uncouplers of oxidative phosphorylation.

On a volume basis, GCPs had 8- to 10-fold higher respiratory activities than MCPs, but had a low Chi content and lacked the activity of NADP-glyceraldehyde-3-phosphate dehydrogenase (NADP-GAPD), the Calvin cycle enzyme.

From these results, we concluded that oxidative phosphorylation plays a main role in ATP production in guard cells and that guard cells have a heterotrophic feature.

Salicylhydroxamic acid (SHAM) in combination with KCN or NaN3 strongly inhibited O2uptake, indicating the presence of cyanide-resistant respiration in guard cells.

Phenylmercuric acetate (PMA), a potent inhibitor of stomatal opening, reduced the ATP content of GCPs by about 90%, whereas it had a relatively small effect on the ATP level of MCPs.

The specific effect of PMA on GCPs is discussed.


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