Crassulacean Acid Metabolism and Diurnal Variations of Internal CO2 and O2 Concentrations in Sedum praealtum DC

Spalding, MH; Stumpf, DK; Ku, Msb; Burris, R. H.; Edwards, G. E.

doi:10.1071/pp9790557

Cited by 95 publications

(60 citation statements)

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“…Individual patches of tissue display low PSII during photosynthesis in air when internal CO 2 concentrations may be as low as about 100 ppm (26) and high PSII during malic acid remobilization when CO 2 concentration may reach 10,000 ppm (27). Thus, individual oscillators can arise from differences in the storage capacity for malic acid and the timing of malic acid decarboxylation.…”

Section: Resultsmentioning

confidence: 99%

Spatiotemporal variation of metabolism in a plant circadian rhythm: The biological clock as an assembly of coupled individual oscillators

Rascher

Hutt

Siebke

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

115

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The complex dynamic properties of biological timing in organisms remain a central enigma in biology despite the increasingly precise genetic characterization of oscillating units and their components. Although attempts to obtain the time constants from oscillations of gene activity and biochemical units have led to substantial progress, we are still far from a full molecular understanding of endogenous rhythmicity and the physiological manifestations of biological clocks. Applications of nonlinear dynamics have revolutionized thinking in physics and in biomedical and life sciences research, and spatiotemporal considerations are now advancing our understanding of development and rhythmicity. Here we show that the well known circadian rhythm of a metabolic cycle in a higher plant, namely the crassulacean acid metabolism mode of photosynthesis, is expressed as dynamic patterns of independently initiated variations in photosynthetic efficiency ( PSII) over a single leaf. Noninvasive highly sensitive chlorophyll fluorescence imaging reveals randomly initiated patches of varying PSII that are propagated within minutes to hours in wave fronts, forming dynamically expanding and contracting clusters and clearly dephased regions of PSII. Thus, this biological clock is a spatiotemporal product of many weakly coupled individual oscillators, defined by the metabolic constraints of crassulacean acid metabolism. The oscillators operate independently in space and time as a consequence of the dynamics of metabolic pools and limitations of CO 2 diffusion between tightly packed cells.A current trend in physics and life sciences is the investigation of spatiotemporal patterns that appear in phenomena that were formerly thought to be solely time dependent. Rhythmic phenomena are common in nature and are excellent models for investigation of spatial dynamics because of their regular structure. However, the complex dynamic properties of timing in organisms and biological systems remain a central enigma in biology despite the increasingly precise genetic characterization of oscillating units and their components (1, 2). For example, phase synchronization of predator-prey dynamics in spatially extended ecological systems emerges only when the building blocks are spatially arranged and interrelated by flows of signaling compounds (3). The challenge is to understand how the spatial organization of the components of a system can influence overall temporal development.The circadian rhythm of net CO 2 exchange (JCO 2 ) in crassulacean acid metabolism (CAM) plants in continuous light is regarded as a time-dependent generic model system for exploration of endogenous rhythmicity in a well understood metabolic pathway (4-6). During the normal day͞night cycle, CAM can be divided in four phases (7). In phase I, nocturnal CO 2 fixation by phosphoenolpyruvate-carboxylase (PEPCase) leads to the formation of malic acid that is removed from the site of its formation in the cytoplasm by active accumulation to the central cell vacuole. Malic acid exerts ...

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Section: Resultsmentioning

confidence: 99%

Spatiotemporal variation of metabolism in a plant circadian rhythm: The biological clock as an assembly of coupled individual oscillators

Rascher

Hutt

Siebke

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

115

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“…1). This decarboxylation can lead to generation of internal leaf CO 2 partial pressures greater than 100 times atmospheric levels (Cockburn et al 1979;Spalding et al 1979), reduction in stomatal opening and transpiration and sometimes even release of CO 2 from the leaf despite low stomatal conductance (Frimert et al 1986). Decarboxylation is catalysed by either cytosolic PEP carboxykinase (PEPCK) or cytosolic NADP + -and/or mitochondrial NAD + -malic enzymes (ME) (Smith and Bryce 1992;Christopher and Holtum 1996;Holtum et al 2005).…”

Section: Phases Of Cammentioning

confidence: 99%

Evolution along the crassulacean acid metabolism continuum

Silvera

Neubig

Whitten

et al. 2010

Functional Plant Biol.

198

199

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Abstract. Crassulacean acid metabolism (CAM) is a specialised mode of photosynthesis that improves atmospheric CO 2 assimilation in water-limited terrestrial and epiphytic habitats and in CO 2 -limited aquatic environments. In contrast with C 3 and C 4 plants, CAM plants take up CO 2 from the atmosphere partially or predominantly at night. CAM is taxonomically widespread among vascular plants and is present in many succulent species that occupy semiarid regions, as well as in tropical epiphytes and in some aquatic macrophytes. This water-conserving photosynthetic pathway has evolved multiple times and is found in close to 6% of vascular plant species from at least 35 families. Although many aspects of CAM molecular biology, biochemistry and ecophysiology are well understood, relatively little is known about the evolutionary origins of CAM. This review focuses on five main topics: (1) the permutations and plasticity of CAM, (2) the requirements for CAM evolution, (3) the drivers of CAM evolution, (4) the prevalence and taxonomic distribution of CAM among vascular plants with emphasis on the Orchidaceae and (5) the molecular underpinnings of CAM evolution including circadian clock regulation of gene expression.

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“…Whereas it is clear that decarboxylation generates very high internal partial pressures of CO 2 during phase III (typically 1.8%-8%) (Cockburn et al, 1979;Spalding et al, 1979;Osmond et al, 1999), the low internal conductance of CO 2 from the stomatal cavity to Rubisco active sites results in a very low pCO 2 during atmospheric CO 2 uptake (Maxwell et al, 1997). Therefore, during phases II and IV, the internal partial pressure of CO 2 is limiting for Rubisco carboxylase activity, but is saturating for PEPC (Osmond et al, 1999).…”

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confidence: 99%

Modulation of Rubisco Activity during the Diurnal Phases of the Crassulacean Acid Metabolism Plant Kalanchoëdaigremontiana

Maxwell¹,

Borland²,

Haslam³

et al. 1999

Plant Physiology

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The regulation of Rubisco activity was investigated under high, constant photosynthetic photon flux density during the diurnal phases of Crassulacean acid metabolism in Kalanchoëdaigremontiana Hamet et Perr. During phase I, a significant period of nocturnal, C4-mediated CO2 fixation was observed, with the generated malic acid being decarboxylated the following day (phase III). Two periods of daytime atmospheric CO2 fixation occurred at the beginning (phase II, C4–C3 carboxylation) and end (phase IV, C3–C4 carboxylation) of the day. During the 1st h of the photoperiod, when phosphoenolpyruvate carboxylase was still active, the highest rates of atmospheric CO2 uptake were observed, coincident with the lowest rates of electron transport and minimal Rubisco activity. Over the next 1 to 2 h of phase II, carbamylation increased rapidly during an initial period of decarboxylation. Maximal carbamylation (70%–80%) was reached 2 h into phase III and was maintained under conditions of elevated CO2 resulting from malic acid decarboxylation. Initial and total Rubisco activity increased throughout phase III, with maximal activity achieved 9 h into the photoperiod at the beginning of phase IV, as atmospheric CO2 uptake recommenced. We suggest that the increased enzyme activity supports assimilation under CO2-limited conditions at the start of phase IV. The data indicate that Rubisco activity is modulated in-line with intracellular CO2 supply during the daytime phases of Crassulacean acid metabolism.

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Crassulacean Acid Metabolism and Diurnal Variations of Internal CO2 and O2 Concentrations in Sedum praealtum DC

Cited by 95 publications

References 0 publications

Spatiotemporal variation of metabolism in a plant circadian rhythm: The biological clock as an assembly of coupled individual oscillators

Spatiotemporal variation of metabolism in a plant circadian rhythm: The biological clock as an assembly of coupled individual oscillators

Evolution along the crassulacean acid metabolism continuum

Modulation of Rubisco Activity during the Diurnal Phases of the Crassulacean Acid Metabolism Plant Kalanchoëdaigremontiana

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