Photocontrol of Sorghum Leaf Phosphoenolpyruvate Carboxylase

Thomas, Martine; Crétin, Claude; Kéryer, Eliane; Vidal, Jean; Gadal, Pierre

doi:10.1104/pp.85.1.243

Cited by 22 publications

(4 citation statements)

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“…However, those seedlings which received an additional far-red treatment showed a reversal in sucrose-P synthase activity by 2 h postillumination, resulting in an approximately 50% decrease in enzyme activity. These data demonstrate the reversibility of sucrose-P synthase activity by illumination with red followed by far-red and further supports the hypothesis that phytochrome may be involved in light dependent changes in sucrose-P synthase activity in maize (16).…”

Section: Resultssupporting

confidence: 85%

“…The other form found in greening leaves was designated G-PERPC and occurred only after etiolated leaves were exposed to light. Later, Thomas et al (16) showed that the activity of G-PEPC was sensitive to red and far-red treatments. A 10-min exposure to red stimulated G-PEPC, whereas far-red (either alone or following a red treatment) caused a substantial inhibition of the G-PEPC isoform.…”

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confidence: 99%

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Phytochrome Mediated Regulation of Sucrose Phosphate Synthase Activity in Maize

Vassey

1988

Plant Physiol.

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The extractable activity of sucrose phosphate synthase was determined in etiolated seedlings of maize (Zea mays L.), soybean (Glycine max [L.] Merr.), and sugar beet (Beta vulgaris L.) following treatments of changing light quality. A 30-minute illumination of 30 microeinsteins per square meter per second white light produced a three-fold increase in sucrose phosphate synthase activity at 2 hours postillumination when compared to seedlings maintained in total darkness. Etiolated maize seedlings treated with 3.6 microeinsteins per square meter per second of red and far-red light showed a 50% increase and a 50% decrease in sucrose phosphate synthase activity, respectively, when compared to etiolated maize seedlings treated with white light. Maize seedlings exposed for 30 minutes to red followed by 30 minutes to far-red showed an initial increase in sucrose phosphate synthase activity followed by a rapid decrease to control level. Neither soybean or sugar beet sucrose phosphate synthase responded to the 30-minute illumination of white light. Phytochrome is involved in sucrose phosphate synthase regulation in maize, whereas it is not responsible for changes in sucrose phosphate synthase activity in soybean or sugar beet.Sucrose-P synthase appears to be a major control point in sucrose formation during photoassimilation of CO2 (10). Sucrose synthesis is apparently the only physiological function ofsucrose-P synthase, with the equilibrium constant for sucrose synthesis about 2 (1). This makes sucrose-P synthase a focal point for studying regulation of sucrose metabolism and partitioning.Vidal and Gadal (18) and Vidal et al. (19) found that two isoforms of PEPC' were present in etiolated leaves of sorghum. One form, found in the eitolated leaves, was designated E-PEPC. The other form found in greening leaves was designated G-PERPC and occurred only after etiolated leaves were exposed to light. Later, Thomas et al. (16) showed that the activity of G-PEPC was sensitive to red and far-red treatments. A 10-min exposure to red stimulated G-PEPC, whereas far-red (either alone or following a red treatment) caused a substantial inhibition of the G-PEPC isoform. They concluded from these experiments that phytochrome was the photoreceptor triggering changes in enzyme activity.The present study was designed to examine the role of light ' Abbreviations: PEPC, phosphoenolpyruvate carboxylase; G6P, glucose 6-phosphate; UDPG, uridine 5'-diphosphoglucose; PPFD, photosynthetic photon flux density. quality on the extractable activity of sucrose-P synthase in maize, soybean, and sugar beets. This was done using 10-day-old seedlings of each species grown in total darkness and illuminating them with white light, red, far-red, or red followed by far red. MATERIALS AND METHODSPlant Materials. Maize (Zea mays L., cv FS854), soybean (Glycine max. [L.] Merr., cv Pioneer 1082), and sugar beet (Beta vulgaris L., cv Great Western multigerm hybrid) seeds were germinated in darkness then planted in 7 cm x 7 cm plastic pots containing ver...

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Section: Resultssupporting

confidence: 85%

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confidence: 99%

Phytochrome Mediated Regulation of Sucrose Phosphate Synthase Activity in Maize

Vassey

1988

Plant Physiol.

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“…Nagy et al (1988), however, found no diurnal changes in the level of wheat SSu mRNA. The transcriptional activity of PEPC, another lightinduced gene family (Nelson et al, 1984;Thomas et al, 1987), also showed no diurnal fluctuations (Figure 1). Whether these differences reflect differences between monocots and dicots or between plant species or are due to differences in sensitivity of experimental technique remains to be seen.…”

Section: Discussionmentioning

confidence: 97%

Transcriptional regulation by a circadian rhythm.

Taylor

1989

Plant Cell

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Transcription of genes encoding the light-harvesting chlorophyll a/b protein (Cab) was shown previously to be regulated by light and a number of developmental factors. ! show that a circadian rhythm in transcriptional activity is superimposed on these other regulatory programs. In vitro transcription measurements in isolated maize leaf nuclei demonstrated that changes in transcription are not coincident with light-dark transitions and that diurnal changes in transcription continue in continuous light and disappear in complete darkness. Light intensity influences the amplitude of transcriptional changes but has no effect on periodicity. Major diurnal changes in Cab mRNA are evident not only in developing seedling leaves, but also in mature, fully expanded leaves. Genes encoding phosphoenolpyruvate carboxylase and the cytosolic form of aldolase show no diurnal changes in transcription.

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“…The mechanism of light modulation was somewhat clarified by Monreal and colleagues [31], who elaborated on the participation of PLD and PA in the signaling cascade of light-dependent upregulation of a sorghum leaf PEPC. It has been proposed that a light signal is the primary event that leads to the activation of phospholipase C and the synthesis of PEPC-PK in the mesophyll of C 4 plants [41]. It was also shown that light increased the PLD activity and production of PA in sorghum leaf discs, thus supporting a link between PLD-dependent PA production and a light signal [31,42].…”

Section: Posttranslational Modifications (Ptms): Phosphorylation and Monoubiquitination Of Pepcsmentioning

confidence: 91%

Differential Expression, Tissue-Specific Distribution, and Posttranslational Controls of Phosphoenolpyruvate Carboxylase

Caburatan

Park

2021

Plants

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Phosphoenolpyruvate carboxylase (PEPC) is a ubiquitous cytosolic enzyme, which is crucial for plant carbon metabolism. PEPC participates in photosynthesis by catalyzing the initial fixation of atmospheric CO2 and is abundant in both C4 and crassulacean acid metabolism leaves. PEPC is differentially expressed at different stages of plant development, mostly in leaves, but also in developing seeds. PEPC is known to show tissue-specific distribution in leaves and in other plant organs, such as roots, stems, and flowers. Plant PEPC undergoes reversible phosphorylation and monoubiquitination, which are posttranslational modifications playing important roles in regulatory processes and in protein localization. Phosphorylation activates the PEPC enzyme, making it more sensitive to glucose-6-phosphate and less sensitive to malate or aspartate. PEPC phosphorylation is known to be diurnally regulated and delicately changed in response to various environmental stimuli, in addition to light. PEPCs belong to a small gene family encoding several plant-type and distantly related bacterial-type PEPCs. This paper provides a minireview of the general information on PEPCs in both C4 and C3 plants.

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Photocontrol of Sorghum Leaf Phosphoenolpyruvate Carboxylase

Abstract: The mechanism underlying the light effect on phosphoenolpyruvate carboxylase (PEPC) from the C-plant sorghum (Sorgkwm vulgare Pers., var

Cited by 22 publications

References 9 publications

Phytochrome Mediated Regulation of Sucrose Phosphate Synthase Activity in Maize

Phytochrome Mediated Regulation of Sucrose Phosphate Synthase Activity in Maize

Transcriptional regulation by a circadian rhythm.

Differential Expression, Tissue-Specific Distribution, and Posttranslational Controls of Phosphoenolpyruvate Carboxylase

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