Abstract
Net CO2 and water vapor exchange were studied in the Crassulacean acid metabolism plant Kalanchoë pinnáta during a normal 12-hour light/12-hour dark cycle and during a prolonged light period. Leaf temperature and leaf-air vapor pressure difference were kept constant at 20 C and 9 to 10 millibar. There was a 25% increase in the rate of CO2 fixation during the first 6 hours prolonged light without change in stomatal conductance. This was associated with a decrease in the intracellular partial pressure of CO2, a decrease in the stimulation of net CO2 uptake by 2% O2, and a decrease in the CO2 compensation point from 45 to 0 microbar. In the normal light period after deacidification, leaves showed a normal light dependence of CO2 uptake but, in prolonged light, CO2 uptake was scarcely light-dependent. The increase in titratable acidity in prolonged light was similar to that in the dark.
The results suggest a change from C3 photosynthetic CO2 fixation in the second part of the 12-hour light period to a mixed metabolism in prolonged light with both ribulose bisphosphate carboxylase and phosphoenolpyruvate carboxylase as primary carboxylating enzymes.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Bloom A. J. Diurnal Ion Fluctuations in the Mesophyll Tissue of the Crassulacean Acid Metabolism Plant Mesembryanthemum crystallinum. Plant Physiol. 1979 Dec;64(6):919–923. doi: 10.1104/pp.64.6.919. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bradbeer J. W., Ranson S. L., Stiller M. Malate Synthesis in Crassulacean Leaves. I. The Distribution of C in Malate of Leaves Exposed to CO(2) in the Dark. Plant Physiol. 1958 Jan;33(1):66–70. doi: 10.1104/pp.33.1.66. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cockburn W. Relationships between Stomatal Behavior and Internal Carbon Dioxide Concentration in Crassulacean Acid Metabolism Plants. Plant Physiol. 1979 Jun;63(6):1029–1032. doi: 10.1104/pp.63.6.1029. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nobel P. S., Hartsock T. L. Resistance Analysis of Nocturnal Carbon Dioxide Uptake by a Crassulacean Acid Metabolism Succulent, Agave deserti. Plant Physiol. 1978 Apr;61(4):510–514. doi: 10.1104/pp.61.4.510. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Powles S. B., Osmond C. B. Photoinhibition of intact attached leaves of c(3) plants illuminated in the absence of both carbon dioxide and of photorespiration. Plant Physiol. 1979 Dec;64(6):982–988. doi: 10.1104/pp.64.6.982. [DOI] [PMC free article] [PubMed] [Google Scholar]
- VICKERY H. B. The behavior of the organic acids and starch of Bryophyllum leaves during culture in continuous light. J Biol Chem. 1953 Nov;205(1):369–381. [PubMed] [Google Scholar]
- Winter K. Day/Night Changes in the Sensitivity of Phosphoenolpyruvate Carboxylase to Malate during Crassulacean Acid Metabolism. Plant Physiol. 1980 May;65(5):792–796. doi: 10.1104/pp.65.5.792. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wong S. C., Cowan I. R., Farquhar G. D. Leaf Conductance in Relation to Assimilation in Eucalyptus pauciflora Sieb. ex Spreng: Influence of Irradiance and Partial Pressure of Carbon Dioxide. Plant Physiol. 1978 Oct;62(4):670–674. doi: 10.1104/pp.62.4.670. [DOI] [PMC free article] [PubMed] [Google Scholar]