Characterization of carbon metabolism inOpuntia ficus-indicaMill. exhibiting the idling mode of Crassulacean acid metabolism
✍ Scribed by J. Brulfert; M. Kluge; D. Guerrier; O. Queiroz
- Publisher
- Springer-Verlag
- Year
- 1987
- Tongue
- English
- Weight
- 676 KB
- Volume
- 170
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
Upon transfer from well-watered conditions to total drought, long-day-grown cladodes of Opuntia ficus-indica Mill. shift from full Crassulacean acid metabolism (CAM) to CAM-idling. Experiments using (14)C-tracers were conducted in order to characterize the carbon-flow pattern in cladodes under both physiological situations. Tracer was applied by (14)CO2 fumigations and NaH(14)CO3 injections during the day-night cycle. The results showed that behind the closed stomata, mesophyll cells of CAM-idling plants retained their full capacity to metabolize CO2 in light and in darkness. Upon the induction of CAM-idling the level of the capacity of phosphoenolpyruvate carboxylase (EC 4.1.1.31) was maintained. By contrast, malate pools decreased, displaying finally only a small or no day-night oscillation. The capacity of NADP-malic enzyme (EC 1.1.1.40) decreased in parallel with the reduction in malate pools. Differences in the labelling patterns, as influenced by the mode of tracer application, are discussed.