Stomatal regulation in CAM plants
Pedro J. Aphalo
aphalo at cc.joensuu.fi
Fri Nov 8 01:31:05 EST 1996
Peter Werner wrote:
> How is the opening and closing of stomata regulated in CAM plants? I've
> looked through several plant physiology books and they state nothing more
> than the obvious - CAM plants open their stomates at night and close them
> during the day - but no explanation as to how this is done.
> My guess is that their response to light is similar but opposite to that
> of other plants. Light activates cytochromes and K+ is pumped *out* of
> the guard cells, water follows, turgor decreases and the stomatal openings
> are closed.
> I would also guess that CAM guard cells don't respond to CO2 levels,
> unlike most plants. In most plants, an increased CO2 proportion in the
> substomatal air space is a sign that photosynthesis is slowing down and
> light is disappearing. Because CAM plants fix CO2 at night and release
> it during the day, however, they maintain a relatively high level even
> while photosynthesizing, hence, it wouldn't seem that CO2 levels would
> be a very useful way of distinguishing day from night in these plants.
> Are my speculations about CAM plant guard cell regulation accurate or am
> I barking entirely up the wrong tree?
I think your speculations are not very accurate, read section 6.4.1,
pages 147-148 in:
Willmer,C; Fricker,M (1996): Stomata. 2nd ed. (Series Eds: Black,M;
Charlwood,B. Topics in Plant Functional Biology, 2.) Chapman and Hall,
London. 375 pages.
You may also want to look at these papers:
Santamaria,JM; Herrera,JL; Robert,ML (1995): Stomatal physiology of a
micropropagated cam plant - agave tequilana (weber). Plant Growth
Regulation 16(3, May), 211-214.
Mawson,BT; Zaugg,MW (1994): Modulation of light-dependent stomatal
opening in isolated epidermis following induction of crassulacean acid
metabolism in mesembryanthemum crystallinum L. J. Plant Phys. 144(6,
I hope this helps,
Pedro J. Aphalo
University of Joensuu, Faculty of Forestry
e-mail: aphalo at cc.joensuu.fi
More information about the Plantbio