Abstract
Experiments were performed to test the hypothesis that succulents “shift” their method of photosynthetic metabolism in response to environmental change. Our data showed that there were at least three different responses of succulents to plant water status. When plant water status of Portulacaria afra (L.) Jacq. was lowered either by withholding water or by irrigating with 2% NaCl, a change from C3-photosynthesis to Crassulacean acid metabolism (CAM) occurred. Fluctuation of titratable acidity and nocturnal CO2 uptake was induced in the stressed plants. Stressed Peperomia obtusifolia A. Dietr. plants showed a change from C3-photosynthesis to internal cycling of CO2. Acid fluctuation commenced in response to stress but exogenous CO2 uptake did not occur. Zygocactus truncatus Haworth plants showed a pattern of acid fluctuation and nocturnal CO2 uptake typical of CAM even when well irrigated. The cacti converted from CAM to an internal CO2 cycle similar to Peperomia when plants were water-stressed. Reverse phase gas exchange in succulents results in low water loss to carbon gain. Water is conserved and low levels of metabolic activity are maintained during drought periods by complete stomatal closure and continual fluctuation of organic acids.
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Selected References
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- Lerman J. C. Variation in the carbon isotope composition of a plant with crassulacean Acid metabolism. Plant Physiol. 1974 Apr;53(4):581–584. doi: 10.1104/pp.53.4.581. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Szarek S. R., Johnson H. B., Ting I. P. Drought Adaptation in Opuntia basilaris: Significance of Recycling Carbon through Crassulacean Acid Metabolism. Plant Physiol. 1973 Dec;52(6):539–541. doi: 10.1104/pp.52.6.539. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Szarek S. R., Ting I. P. Seasonal Patterns of Acid Metabolism and Gas Exchange in Opuntia basilaris. Plant Physiol. 1974 Jul;54(1):76–81. doi: 10.1104/pp.54.1.76. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ting I. P., Hanscom Z. Induction of Acid Metabolism in Portulacaria afra. Plant Physiol. 1977 Mar;59(3):511–514. doi: 10.1104/pp.59.3.511. [DOI] [PMC free article] [PubMed] [Google Scholar]