Stomatal responses to carbon dioxide of isolated epidermis from a C3plant, theArgenteummutant ofPisum sativumL., and a crassulacean-acid-metabolism plantKalanchoë daigremontianaHamet et Perr
✍ Scribed by P. C. Jewer; T. F. Neales; L. D. Incoll
- Publisher
- Springer-Verlag
- Year
- 1985
- Tongue
- English
- Weight
- 599 KB
- Volume
- 164
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
The response of stomata in isolated epidermis to the concentration of CO/in the gaseous phase was examined in a C 3 species, the Argenteum mutant of Pisum sativum, and a crassulacean-acidmetabolism (CAM) species, Kalancho6 daigremontiana. Epidermis from leaves of both species was incubated on buffer solutions in the presence of air containing various volume fractions of COg (0 to 10000-10-6). In both species and in the light and in darkness, the effect of COg was to inhibit stomatal opening, the maximum inhibition of opening occurring in the range 0 to 360" 10-6. The inhibition of opening per unit change in concentration was greatest between volume fractions of 0 and 240-10 -6 . There was little further closure above the volume fraction of 360.10 -6 , i.e. approximately ambient concentration of CO2. Thus, although leaves of CAM species may experience much higher internal concentrations of CO 2 in the light than those of C 3 plants, this does not affect the sensitivity of their stomata to CO 2 concentration or the range over which they respond. Stomatal responses to CO 2 were similar in both the light and the dark, indicating that effects of CO 2 on stomata occur via mechanisms which are independent of light. The responses of stomata to COg in the gaseous phase took place without the treatments changing the pH of the buffered solutions. Thus it is unlikely that CO2 elicited stomatal movement by changing either the pH or the HCO~-/ CO~-equilibria. It is suggested that the concentration of dissolved unhydrated CO 2 may be the effector of stomatal movement and that its activity is related to its reactivity with amines.