The Circadian Clock in CAM Plants

Hartwell, James

doi:10.1002/9780470988527.ch9

Cited by 20 publications

(25 citation statements)

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“…The robust circadian rhythm of CAM CO 2 exchange in LL conditions for the wild type ( Figures 3A and 3B) has been shown to correlate tightly with circadian clock control of PPCK and the phosphorylation state of PPC and its K i for malate (Hartwell, 2005(Hartwell, , 2006Dever et al, 2015). Since CO 2 exchange rhythms in LL conditions for rPPCK1-1 and rPPCK1-3 showed, at best, low-amplitude rhythmicity in well-watered plants ( Figures 3A and 3B), it was important to also investigate the circadian regulation of the transcript abundance of KfPPCK1 under LL conditions.…”

Section: Regulation Of Circadian Clock Genes Under Free-running Condimentioning

confidence: 82%

“…In constant light, free-running circadian conditions (LL; constant light 100 mmol m 22 s 21 , and temperature, 15°C), detached LP6 from wild-type plants displayed the characteristic, robust, and persistent CAM circadian rhythm, with oscillating peaks and troughs of CO 2 fixation (Figure 3) (Wilkins, 1992;Hartwell, 2006). rPPCK1-1 and rPPCK1-3 showed a dampening of the CO 2 fixation rhythm in constant conditions, with a dramatic reduction in rhythm amplitude ( Figure 3A).…”

Section: Gas Exchange Characteristics Under Constant Light and Tempermentioning

confidence: 99%

“…Since the first discovery of PPCK activity and its circadian control in 1991 (Carter et al, 1991), through the subsequent cloning and characterization of the gene encoding this remarkable protein kinase in 1999 (Hartwell et al, 1999), there has been a long-held assumption that this circadian clock-controlled kinase is crucial for the temporal coordination and optimization of nocturnal atmospheric CO 2 fixation in CAM species, and the associated persistent circadian rhythm of CO 2 exchange observed under constant conditions in CAM species such as K. fedtschenkoi and K. daigremontiana (Wilkins, 1992;Nimmo, 2003;Wyka et al, 2004;Hartwell, 2006). However, it has not been possible previously to perturb genetically the level of PPCK activity and dark period PPC phosphorylation in a CAM species; thus, it has not been possible to test the validity of this long held assumption about the pivotal role of PPCK in the circadian control of CAM.…”

Section: Impact Of Silencing Kfppck1 On Circadian Rhythms Of Cam Co 2mentioning

confidence: 99%

“…In the light, malate decarboxylation generates CO 2 that is refixed by Rubisco in the Calvin cycle, referred to as secondary CO 2 fixation. Both primary and secondary CO 2 fixation occurs in each leaf mesophyll cell; therefore, strict temporal regulation is required to prevent futile cycling between carboxylation and decarboxylation (Hartwell, 2005(Hartwell, , 2006). …”

Section: Introductionmentioning

confidence: 99%

“…PPCK remains the only well-defined, temporal/circadian control point for CAM (Hartwell, 2006(Hartwell, , 2016. To further elucidate the role of PPC phosphorylation in the temporal control of CO 2 fixation associated with CAM, and the extent to which this phospho-regulation step helps to prevent metabolic futile cycling during CAM, we generated stable transformants of K. fedtschenkoi expressing RNA interference (RNAi) constructs that targeted the degradation of endogenous KfPPCK1 transcripts.…”

Section: Introductionmentioning

confidence: 99%

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Phosphorylation of Phosphoenolpyruvate Carboxylase Is Essential for Maximal and Sustained Dark CO₂ Fixation and Core Circadian Clock Operation in the Obligate Crassulacean Acid Metabolism Species Kalanchoë fedtschenkoi

et al. 2017

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Section: Regulation Of Circadian Clock Genes Under Free-running Condimentioning

confidence: 82%

Section: Gas Exchange Characteristics Under Constant Light and Tempermentioning

confidence: 99%

Section: Impact Of Silencing Kfppck1 On Circadian Rhythms Of Cam Co 2mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Phosphorylation of Phosphoenolpyruvate Carboxylase Is Essential for Maximal and Sustained Dark CO₂ Fixation and Core Circadian Clock Operation in the Obligate Crassulacean Acid Metabolism Species Kalanchoë fedtschenkoi

et al. 2017

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Crassulacean Acid Metabolism

Lüttge¹

2015

Encyclopedia of Life Sciences

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Crassulacean acid metabolism (CAM) is a carbon dioxide acquisition, transient storage and concentrating mechanism of plants based on organic acid synthesis. Amongst 350 000 species of vascular plants, 21 000 species perform CAM. In this variant of photosynthesis, carbon dioxide can be fixed nocturnally in the dark and is stored in the form of organic acids from which it is remobilised during the day for assimilation in the light. This has arisen polyphyletically during evolution. It is an ecophysiological adaptation that allows carbon dioxide acquisition with exceptionally economic use of water. CAM allows acclimation to a variety of interacting stresses. It is an adaptation for survival and not for high productivity. Nevertheless, performance of CAM species on drought‐prone marginal lands makes them potential alternative crop plants and biofuel plants. CAM is regulated in a natural night/day rhythm, but can also oscillate freely under the control of circadian biological clocks. Key Concepts Metabolic mechanisms concentrating carbon dioxide internally in plants are important for photosynthesis at the low external carbon dioxide concentration in the present atmosphere. Massive nocturnal CO 2 uptake, fixation and storage in the form of organic acids result in inorganic carbon acquisition with high water‐use efficiency (WUE). Rearranged internal management of available metabolic housekeeping functions can generate new metabolic options of adaptive value. Generation of isoforms of housekeeping enzymes can facilitate polyphyletic evolution of new metabolic pathways. Circadian oscillations can be controlled by different biological clocks, which are feedback related to each other and present in many copies. Flexibility in the expression of metabolic pathway variants facilitates adaptation under variable stress situations. Stress adaptation in plants is for survival and mostly not for high productivity. Resistance to drought stress and high water‐use efficiency supports the quest for new crop plants including biofuel crops to be grown on marginal land.

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The Kalanchoë genome provides insights into convergent evolution and building blocks of crassulacean acid metabolism

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Crassulacean acid metabolism (CAM) is a water-use efficient adaptation of photosynthesis that has evolved independently many times in diverse lineages of flowering plants. We hypothesize that convergent evolution of protein sequence and temporal gene expression underpins the independent emergences of CAM from C3 photosynthesis. To test this hypothesis, we generate a de novo genome assembly and genome-wide transcript expression data for Kalanchoë fedtschenkoi, an obligate CAM species within the core eudicots with a relatively small genome (~260 Mb). Our comparative analyses identify signatures of convergence in protein sequence and re-scheduling of diel transcript expression of genes involved in nocturnal CO2 fixation, stomatal movement, heat tolerance, circadian clock, and carbohydrate metabolism in K. fedtschenkoi and other CAM species in comparison with non-CAM species. These findings provide new insights into molecular convergence and building blocks of CAM and will facilitate CAM-into-C3 photosynthesis engineering to enhance water-use efficiency in crops.

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The Circadian Clock in CAM Plants

Cited by 20 publications

References 67 publications

Phosphorylation of Phosphoenolpyruvate Carboxylase Is Essential for Maximal and Sustained Dark CO₂ Fixation and Core Circadian Clock Operation in the Obligate Crassulacean Acid Metabolism Species Kalanchoë fedtschenkoi

Phosphorylation of Phosphoenolpyruvate Carboxylase Is Essential for Maximal and Sustained Dark CO₂ Fixation and Core Circadian Clock Operation in the Obligate Crassulacean Acid Metabolism Species Kalanchoë fedtschenkoi

Crassulacean Acid Metabolism

The Kalanchoë genome provides insights into convergent evolution and building blocks of crassulacean acid metabolism

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The Circadian Clock in CAM Plants

Cited by 20 publications

References 67 publications

Phosphorylation of Phosphoenolpyruvate Carboxylase Is Essential for Maximal and Sustained Dark CO2 Fixation and Core Circadian Clock Operation in the Obligate Crassulacean Acid Metabolism Species Kalanchoë fedtschenkoi

Phosphorylation of Phosphoenolpyruvate Carboxylase Is Essential for Maximal and Sustained Dark CO2 Fixation and Core Circadian Clock Operation in the Obligate Crassulacean Acid Metabolism Species Kalanchoë fedtschenkoi

Crassulacean Acid Metabolism

The Kalanchoë genome provides insights into convergent evolution and building blocks of crassulacean acid metabolism

Contact Info

Product

Resources

About

Phosphorylation of Phosphoenolpyruvate Carboxylase Is Essential for Maximal and Sustained Dark CO₂ Fixation and Core Circadian Clock Operation in the Obligate Crassulacean Acid Metabolism Species Kalanchoë fedtschenkoi

Phosphorylation of Phosphoenolpyruvate Carboxylase Is Essential for Maximal and Sustained Dark CO₂ Fixation and Core Circadian Clock Operation in the Obligate Crassulacean Acid Metabolism Species Kalanchoë fedtschenkoi