Feedback Control of Biological Rhythm in Crassulacean Acid Metabolism by CO2-Uptake Signal**This work is partially supported by the Grant-in-Aid for Scientific Research (25420445), Japan Society for the Promotion of Science.

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. The regulation and flexibility of the crassulacean acid metabolism (CAM) pathway has been investigated in the 'extreme epiphyte' Tillandsia usneoides (L.). Submerging strands of T. usneoides under water, thereby inhibiting the supply of atmospheric CO2, allowed non-invasive in vivo manipulation of the supply of CO2 during the nocturnal Phase I of CAM. Once the plants were removed from submersion, T. usneoides maintained open stomata, and net CO2 uptake occurred throughout most of the photoperiod. Variability in the expression of CAM allowed T. usneoides to compensate for restricted CO2 availability through Phase I of CAM by adjusting gas exchange rates through the photoperiod and subsequent dark period to maintain a constant internal supply of CO2 in the light. Furthermore, T. usneoides demonstrated a gradual, rather than rapid, change in phosphoenolpyruvate carboxylase (PEPC) activation across the day-night cycle, such that PEPC and Rubisco appear to work in tandem in order to maintain carbon balance for this extreme atmospheric bromeliad.

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Degrees of crassulacean acid metabolism in tropical epiphytic and lithophytic ferns

Functional Plant Biology ◽

10.1071/pp99001 ◽

1999 ◽

Vol 26 (8) ◽

pp. 749 ◽

Cited By ~ 30

Author(s):

Joseph A.M. Holtum ◽

Klaus Winter

Keyword(s):

Carbon Isotope ◽

Crassulacean Acid Metabolism ◽

Acid Metabolism ◽

Dark Period ◽

Titratable Acidity ◽

Isotope Ratios ◽

Light Period ◽

Co2 Uptake ◽

Carbon Isotope Ratios ◽

Net Co2 Uptake

Crassulacean acid metabolism (CAM) was observed in three species of tropical ferns, the epiphytes Microsorium punctatum and Polypodium crassifolium and the lithophyte Platycerium veitchii. Polypodium crassifolium and P. veitchii exhibited characteristics of weak CAM. Although no net nocturnal CO2 uptake was observed, the presence of CAM was inferred from nocturnal increases in titratable acidity of 4.7 and 4.1 µequiv (g fr wt)–1 respectively, a reduction in the rates of net CO2 evolution during the first half of the dark period, and the presence of a CAM-like decrease in net CO2 uptake during the early light period. In M. punctatum net CO2 uptake during the first half of the dark period was accompanied by an increase in titratable acidity of 39.2 µequiv (g fr wt)–1 and a pronounced reduction in net CO2 uptake during the early light period. When water was withheld from P. crassifolium and M. punctatum, net CO2 uptake during the light was reduced markedly but there was no change in the extent or patterns of CO2 exhange in the dark. As a consequence, the proportion of carbon gained due to CO2 fixation in the dark increased from 2.8 and 10% to 63.5 and 49.3%, respectively (100% being net CO2 uptake during the light plus the estimated CO2 uptake during the dark). After 9 days without added water, dark CO2 uptake was responsible for the maintenance of a net 24 h carbon gain in P. crassifolium. Platycerium veitchii, P. crassifolium and M. punctatum exhibited carbon isotope ratios of between –25.9 and –22.6‰ indicating that carbon isotope ratios may not, by themselves, be sufficient for the identification of weak CAM. We suggest that CAM may be more prevalent in tropical epiphytic and lithophytic ferns than currently envisaged.

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Regulation of Rubisco activity in crassulacean acid metabolism plants: better late than never

Functional Plant Biology ◽

10.1071/pp01212 ◽

2002 ◽

Vol 29 (6) ◽

pp. 689 ◽

Cited By ~ 39

Author(s):

Kate Maxwell ◽

Howard Griffiths ◽

Brent Helliker ◽

Andrew Roberts ◽

Richard P. Haslam ◽

...

Keyword(s):

Electron Transport ◽

Crassulacean Acid Metabolism ◽

Acid Metabolism ◽

Rubisco Activase ◽

Light Period ◽

Phase Iii ◽

Co2 Uptake ◽

Rubisco Activity ◽

Free Atmosphere ◽

Phase Iv

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. The diurnal regulation of Rubisco was compared for a range of crassulacean acid metabolism (CAM) species in the context of high carboxylation and electron transport capacities, which may be an order of magnitude greater than rates of net CO2 uptake. Early in the light period, Rubisco activity and electron transport were limited when phosphoenolpyruvate carboxylase (PEPC) may have been operating, and maximal extractable activities and activation state for Rubisco were achieved at the end of Phase III, prior to the direct atmospheric uptake of CO2 during Phase IV. The delayed activation was associated with levels of Rubisco activase protein, which reached a maximum at midday, and may account for this pattern of Rubisco activation. This regulation may be modified by environmental conditions - processes that tend to restrict PEPC activity, such as drought stress or incubation of leaves overnight in an oxygen-free atmosphere, release Rubisco from inhibition early in the light period. The quantum yield of light use also tracks Rubisco carboxylation, being particularly low at dawn when PEPC is active. The plasticity in expression of the CAM cycle is therefore matched by the regulation of key carboxylases, with extractable Rubisco activity maximal when drawdown of atmospheric CO2 to cells in succulent CAM tissues is most likely to limit photon utilization shortly after midday, during Phase IV.

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Growth and CO2 uptake for cladodes and fruit of the Crassulacean acid metabolism species Opuntia ficus-indica during fruit development

Physiologia Plantarum ◽

10.1034/j.1399-3054.1994.910423.x ◽

1994 ◽

Vol 91 (4) ◽

pp. 708-714 ◽

Cited By ~ 1

Author(s):

Paolo Inglese ◽

Alvaro A. Israel ◽

Park S. Nobel

Keyword(s):

Fruit Development ◽

Crassulacean Acid Metabolism ◽

Acid Metabolism ◽

Co2 Uptake ◽

Opuntia Ficus Indica

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Corrigendum to: Does the C4 plant Trianthema portulacastrum (Aizoaceae) exhibit weakly expressed crassulacean acid metabolism (CAM)?

Functional Plant Biology ◽

10.1071/fp20247_co ◽

2021 ◽

Vol 48 (12) ◽

pp. 1315

Author(s):

Klaus Winter ◽

Milton Garcia ◽

Aurelio Virgo ◽

Jorge Ceballos ◽

Joseph A. M. Holtum

Keyword(s):

Crassulacean Acid Metabolism ◽

Acid Metabolism ◽

Co2 Exchange ◽

Co2 Uptake ◽

C4 Plant ◽

Low Level ◽

Kranz Anatomy ◽

Trianthema Portulacastrum ◽

Annual Herb ◽

Kinetics Of

We examined whether crassulacean acid metabolism (CAM) is present in Trianthema portulacastrum L. (Aizoaceae), a pantropical, salt-tolerant C4 annual herb with atriplicoid-type Kranz anatomy in leaves but not in stems. The leaves of T. portulacastrum are slightly succulent and the stems are fleshy, similar to some species of Portulaca, the only genus known in which C4 and CAM co-occur. Low- level nocturnal acidification typical of weakly expressed, predominantly constitutive CAM was measured in plants grown for their entire life-cycle in an outdoor raised garden box. Acidification was greater in stems than in leaves. Plants showed net CO2 uptake only during the light irrespective of soil water availability. However, nocturnal traces of CO2 exchange exhibited curved kinetics of reduced CO2 loss during the middle of the night consistent with low-level CAM. Trianthema becomes the second genus of vascular land plants in which C4 and features of CAM have been demonstrated to co-occur in the same plant and the first C4 plant with CAM-type acidification described for the Aizoaceae. Traditionally the stems of herbs are not sampled in screening studies. Small herbs with mildly succulent leaves and fleshy stems might be a numerically significant component of CAM biodiversity.

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Environmental, hormonal and circadian regulation of crassulacean acid metabolism expression

Functional Plant Biology ◽

10.1071/pp01244 ◽

2002 ◽

Vol 29 (6) ◽

pp. 669 ◽

Cited By ~ 29

Author(s):

Tahar Taybi ◽

John C. Cushman ◽

Anne M. Borland

Keyword(s):

Crassulacean Acid Metabolism ◽

Acid Metabolism ◽

Metabolic Adaptation ◽

Circadian Regulation ◽

Co2 Uptake ◽

Cam Plants ◽

Environmental Perturbations ◽

Expression Of Genes ◽

Photosynthetic Plasticity ◽

Short And Long Term

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. Expression of crassulacean acid metabolism (CAM) is characterized by the extreme plasticity observed within and between species. Switches between C3 photosynthesis and CAM, and subsequent 24-h patterns of day/night CO2 uptake, are tightly controlled by a variety of environmental and metabolic factors that optimize the response of CAM plants to the most challenging environments over seasonal and daily time scales. Regulation of the genes and enzymes involved in CAM and connected metabolic pathways occurs at a number of levels (transcriptional through to post-translational). Such multiple levels of control are considered to be the key to the photosynthetic plasticity of CAM. Here, we review some of the primary environmental and hormonal factors controlling CAM plasticity in different CAM-inducible species, with emphasis on the regulatory signalling circuits responsible for this control. We also examine the inherent circadian regulation of the pathway, mainly in the context of the diel regulation of phosphoenolpyruvate carboxylase and the dedicated kinase that modulates its activity. We then consider the role of secondary signals, with emphasis on changes in cytosolic [Ca2+]i and the downstream signalling pathways, based on studies conducted on Mesembryanthemum crystallinum L. Besides representing an important metabolic adaptation, CAM provides an intriguing paradigm for studying the complex signalling mechanisms that control and coordinate the expression of genes under a variety of short- and long-term environmental perturbations.

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Identification of Rhythmic Subsystems in the Circadian Cycle of Crassulacean Acid Metabolism under Thermoperiodic Perturbations

Biological Chemistry ◽

10.1515/bc.2003.080 ◽

2003 ◽

Vol 384 (5) ◽

pp. 721-728 ◽

Cited By ~ 14

Author(s):

A. Bohn ◽

S. Hinderlich ◽

M.-T. Hütt ◽

F. Kaiser ◽

U. Lüttge

Keyword(s):

Crassulacean Acid Metabolism ◽

Acid Metabolism ◽

Intercellular Co2 Concentration ◽

Continuous Light ◽

Co2 Concentration ◽

Co2 Uptake ◽

Frequency Spectra ◽

Temperature Cycles ◽

Net Co2 Uptake ◽

Periodic Temperature

AbstractLeaves of the Crassulacean acid metabolism (CAM) plant Kalanchoë daigremontiana Hamet et Perrier de la Bâthie show overt circadian rhythms in net CO2 uptake, leaf conductance to water and intercellular CO2 concentration, which are entrained by periodic temperature cycles. To probe their sensitivity to thermoperiodic perturbations, intact leaves were exposed to continuous light intensity and temperature cycles with a period of 16 h, applying a set of different baseline temperatures and thermodriver amplitudes. All three overt rhythms were analyzed with respect to their frequency spectra and their phase relations with the thermodriver. For most stimulation protocols, stomatal conductance and net CO2 change were fully or partially entrained by the temperature pulses, while the internal CO2 concentration remained dominated by oscillations in the circadian range. Prolonged time series recorded for up to 22 d in continuous light underline the robustness of these circadian oscillations. This suggests that the overt circadian rhythm of net CO2 uptake in CAM results from the interaction of two coupled original systems: (i) an endogenous cycle of CO2 fixation in the mesophyll, showing very robust periodic activity, and (ii) stomatal movements that respond to environmental stimuli independently of rhythmic processes in the mesophyll, and thus modulate the gas exchange amplitude.

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