Probing the circadian control of phosphoenolpyruvate carboxylase kinase expression in Kalanchoë fedtschenkoi

2002 ◽  
Vol 29 (6) ◽  
pp. 663 ◽  
Author(s):  
James Hartwell ◽  
Gillian A. Nimmo ◽  
Malcolm B. Wilkins ◽  
Gareth I. Jenkins ◽  
Hugh G. Nimmo
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Constant Darkness ◽  
Cam Plants ◽  
Mature Leaves ◽  
Circadian Control ◽  
Detached Leaves ◽  
Translatable Mrna ◽  
Kinase Expression

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. In crassulacean acid metabolism (CAM) plants, phosphoenolpyruvate carboxylase (PEPC) kinase is expressed at night under the control of a circadian oscillator. We have proposed that this is an indirect effect, secondary to circadian fluctuations in the level of a metabolite, possibly cytosolic malate, resulting from a primary effect on the permeability of the tonoplast (Nimmo 2000, Trends in Plant Science 5, 75-80). Here we show that the nocturnal accumulation of PEPC kinase translatable mRNA and phosphorylation of PEPC in Kalanchoë fedtschenkoi is blocked by the protein phosphatase inhibitor cantharidin. This implicates protein dephosphorylation in the circadian pathway that regulates expression of PEPC kinase. We also show that the effect of reducing the temperature from 30 to 15 °C on CO2 fixation by detached leaves held in constant darkness and normal air is 'gated' by the circadian clock. This strongly supports the view that the effect of the clock on the expression of PEPC kinase is secondary rather than direct. We have developed a non-aqueous fractionation protocol that separates the cytosolic material in mature leaves from vacuolar material. The cytosolic malate in mature leaves represents a very small part of the total malate, and its concentration cannot be measured precisely by this method.

How to tell the time: the regulation of phosphoenolpyruvate carboxylase in Crassulacean acid metabolism (CAM) plants

2003 ◽  
Vol 31 (3) ◽  
pp. 728-730 ◽  
Author(s):  
H.G. Nimmo
Keyword(s):  
Circadian Rhythms ◽  
Phosphoenolpyruvate Carboxylase ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Circadian Oscillator ◽  
Cam Plants ◽  
Reversible Phosphorylation ◽  
Circadian Expression ◽  
Phosphoenolpyruvate Carboxylase Kinase ◽  
Co2 Metabolism

Crassulacean acid metabolism (CAM) plants exhibit persistent circadian rhythms of CO2 metabolism. These rhythms are driven by changes in the flux through phosphoenolpyruvate carboxylase, which is regulated by reversible phosphorylation in response to a circadian oscillator. This article reviews progress in our understanding of the circadian expression of phosphoenolpyruvate carboxylase kinase.

scholarly journals Phosphoenolpyruvate carboxylase from pennywort (Umbilicus rupestris). Changes in properties after exposure to water stress

1984 ◽  
Vol 218 (2) ◽  
pp. 387-393 ◽  
Author(s):  
P P Daniel ◽  
J A Bryant ◽  
F I Woodward
Keyword(s):  
Water Stress ◽  
Phosphoenolpyruvate Carboxylase ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Marked Decrease ◽  
Cam Plants ◽  
Allosteric Inhibitor ◽  
Allosteric Effector ◽  
Incomplete Form ◽  
C3 Photosynthesis

Umbilicus rupestris (pennywort) switches from C3 photosynthesis to an incomplete form of crassulacean acid metabolism (referred to as ‘CAM-idling’) when exposed to water stress (drought). This switch is accompanied by an increase in the activity of phosphoenolpyruvate carboxylase. This enzyme also shows several changes in properties, including a marked decrease in sensitivity to acid pH, a lower Km for phosphoenolpyruvate, very much decreased sensitivity to the allosteric inhibitor malate, and increased responsiveness to the allosteric effector glucose 6-phosphate. The Mr of the enzyme remains unchanged, at approx. 185 000. These changes in properties of phosphoenolpyruvate carboxylase are discussed in relation to the roles of the enzyme in C3 and in CAM plants.

scholarly journals Light-responsive expression atlas reveals the effects of light quality and intensity in Kalanchoë fedtschenkoi, a plant with crassulacean acid metabolism

GigaScience ◽  
2020 ◽  
Vol 9 (3) ◽  
Author(s):  
Jin Zhang ◽  
Rongbin Hu ◽  
Avinash Sreedasyam ◽  
Travis M Garcia ◽  
Anna Lipzen ◽  
...  
Keyword(s):  
Light Intensity ◽  
White Light ◽  
Crassulacean Acid Metabolism ◽  
Light Quality ◽  
Acid Metabolism ◽  
Easy Access ◽  
Cam Plants ◽  
A Genome ◽  
Acid Accumulation ◽  
Expression Atlas

Abstract Background Crassulacean acid metabolism (CAM), a specialized mode of photosynthesis, enables plant adaptation to water-limited environments and improves photosynthetic efficiency via an inorganic carbon-concentrating mechanism. Kalanchoë fedtschenkoi is an obligate CAM model featuring a relatively small genome and easy stable transformation. However, the molecular responses to light quality and intensity in CAM plants remain understudied. Results Here we present a genome-wide expression atlas of K. fedtschenkoi plants grown under 12 h/12 h photoperiod with different light quality (blue, red, far-red, white light) and intensity (0, 150, 440, and 1,000 μmol m–2 s–1) based on RNA sequencing performed for mature leaf samples collected at dawn (2 h before the light period) and dusk (2 h before the dark period). An eFP web browser was created for easy access of the gene expression data. Based on the expression atlas, we constructed a light-responsive co-expression network to reveal the potential regulatory relationships in K. fedtschenkoi. Measurements of leaf titratable acidity, soluble sugar, and starch turnover provided metabolic indicators of the magnitude of CAM under the different light treatments and were used to provide biological context for the expression dataset. Furthermore, CAM-related subnetworks were highlighted to showcase genes relevant to CAM pathway, circadian clock, and stomatal movement. In comparison with white light, monochrome blue/red/far-red light treatments repressed the expression of several CAM-related genes at dusk, along with a major reduction in acid accumulation. Increasing light intensity from an intermediate level (440 μmol m−2 s−1) of white light to a high light treatment (1,000 μmol m–2 s–1) increased expression of several genes involved in dark CO2 fixation and malate transport at dawn, along with an increase in organic acid accumulation. Conclusions This study provides a useful genomics resource for investigating the molecular mechanism underlying the light regulation of physiology and metabolism in CAM plants. Our results support the hypothesis that both light intensity and light quality can modulate the CAM pathway through regulation of CAM-related genes in K. fedtschenkoi.

scholarly journals CO2 starvation experiments provide support for the carbon-limited hypothesis on the evolution of CAM-like behaviour in Isoëtes

2020 ◽  
Vol 127 (1) ◽  
pp. 135-141
Author(s):  
Jacob S Suissa ◽  
Walton A Green
Keyword(s):  
Aquatic Ecosystems ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Selective Pressure ◽  
Atmospheric Co2 ◽  
Terrestrial Plants ◽  
Cam Plants ◽  
Acid Accumulation ◽  
Use Efficiency ◽  
Nocturnal Acid Accumulation

Abstract Background and Aims Crassulacean acid metabolism (CAM) is an adaptation to increase water use efficiency in dry environments. Similar biochemical patterns occur in the aquatic lycophyte genus Isoëtes. It has long been assumed and accepted that CAM-like behaviour in these aquatic plants is an adaptation to low daytime carbon levels in aquatic ecosystems, but this has never been directly tested. Methods To test this hypothesis, populations of Isoëtes engelmannii and I. tuckermanii were grown in climate-controlled chambers and starved of atmospheric CO2 during the day while pH was measured for 24 h. Key Results We demonstrate that terrestrial plants exposed to low atmospheric CO2 display diel acidity cycles similar to those in both xerophytic CAM plants and submerged Isoëtes. Conclusions Daytime CO2 starvation induces CAM-like nocturnal acid accumulation in terrestrial Isoëtes, substantiating the hypothesis that carbon starvation is a selective pressure for this physiological behaviour.

Cell organelles from crassulacean acid metabolism (CAM) plants

Planta ◽  
1980 ◽  
Vol 147 (5) ◽  
pp. 477-484 ◽  
Author(s):  
C. Schnarrenberger ◽  
D. Gro� ◽  
Ch. Burkhard ◽  
M. Herbert
Keyword(s):  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Cam Plants ◽  
Cell Organelles
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