The capacity of chlorophyll-a biosynthesis in the mustard seedling cotyledons as modulated by phytochrome and circadian rhythmicity

Gehring, Heinz; Kasemir, H.; Mohr, Hans

doi:10.1007/bf00380692

Cited by 36 publications

(9 citation statements)

References 34 publications

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“…These data indicate that greening and hence chloroplast biogenesis is under circadian control after HS and/or light treatments. Similar findings on Chl accumulation induced via phytochrome have been observed earlier; however, the interpretation of these findings was different (13). Because the same result has not been observed in etiolated plantlets, it would be reasonable to assume that in etiolated plants the circadian clock does not oscillate or, if oscillating, is not under the synchronizing control of a circadian pacemaker but can be synchronized by HS (and/or light).…”

Section: Discussionsupporting

confidence: 67%

The Effect of Heat Shock on Morphogenesis in Barley

Beator¹,

Pötter²,

Kloppstech³

1992

Plant Physiol.

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The effect of daily heat-shock treatments on gene expression and morphogenesis of etiolated barley (Hordeum vulgare) was investigated. Heat-shock treatments in the dark induced shortening of the primary leaves and the coleoptiles to the length of those in light-grown plantlets. In addition, the mRNA levels of the lightinduced genes that were investigated were raised under these conditions and showed distinct oscillations over a period of at least 3 d. While the mRNA levels for chlorophyll a/b binding protein (LHC II), plastocyanin, and the small subunit of ribulose-1,5-bisphosphate carboxylase had maxima between 8 and 12 PM (12-16 h after the last heat-shock treatment), the mRNA levels for thionin oscillated with a phase opposed to that of LHC II. Etiolated barley, the circadian oscillator of which was synchronized by cyclic heatshock treatments, was illuminated for a constant interval at different times of the day; this led to the finding that greening was fastest at the time when the maximal levels of mRNA for LHC II were also observed. Whereas After the discovery of circadian regulation of mRNA levels (19), evidence accumulated suggesting that transcription of light-regulated genes is primarily under the control of the circadian clock (14) and that signal perception occurs via phytochrome (27). Moreover, the phase of the endogeneous clock can be shifted via phytochrome (27). Thus, a primary synchronization between the circadian rhythm of gene expression and the external factor light can be achieved. These findings imply an interaction of phytochrome with the mechanism of the circadian oscillator itself. The signal chain(s) that leads from the receptor(s) via the endogeneous clock mechanism to the transcription of genes is not yet known.To understand more closely the potential effect of circadian rhythm on gene expression and morphogenesis, we studied the influence of external signals (zeitgeber) other than light. Of these, temperature shifts appeared well suited because alterations in the ambient temperature affect the phase of the circadian rhythm (26). The positive effect of temperature oscillations on development was shown in experiments in which it was found that plants grown under constant environmental conditions do not develop properly, whereas a diurnal fluctuation of temperature under otherwise constant conditions has a normalizing effect on plant development (16).In previous studies (20), we have shown that HS2 treatments and diurnal temperature shifts during emergence of pea seedlings in the dark cause morphogenetic changes that are very similar to those induced by far-red light: plumulae are developed, the hooks opened, and the stems shortened. These 'photomorphogenetic' characteristics are accompanied by elevated levels of nuclear-coded, light-inducible mRNAs for LHC II and SSU. ELIPs are another group of lightregulated genes (15); the regulation in their steady-state mRNA level remains entirely light dependent in etiolated pea seedlings whose circadian oscillations were entrained by te...

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Section: Discussionsupporting

confidence: 67%

The Effect of Heat Shock on Morphogenesis in Barley

Beator¹,

Pötter²,

Kloppstech³

1992

Plant Physiol.

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“…2) with an optimum in the blue region of the spectrum are similar to most action spectra for the HIR, at least in this region of the spectrum. For example, similar action spectra have been reported for such diverse responses in higher plants as leaf inclination in wheat (22), ethylene production (3), elongation of hypocotyls in de-etiolated cucumber seedlings (1) and etiolated lettuce seedlings (14,16), and Chl formation in wheat roots (12). Many of these action spectra also show peaks in the far red region of the spectrum.…”

Section: Discussionsupporting

confidence: 57%

Control of Leaf and Stem Growth in Light-grown Pea Seedlings by Two High Irradiance Responses

Elliott¹

1979

Plant Physiol.

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The control exerted by light on leaf and stem growth in light-grown Alaska pea seedlings was studied during the main photoperiod. Two high irradiance responses were observed. The action spectrum for one had a single sharp peak at 600 nanometers. The action spectrum for the other showed a broad peak between 440 and 470 nanomneters. These two light responses must be activated simultaneously for any inhibition of stem growth or promotion of leaf growth. Both action spectra may be explained in terms of the high irradiance response of phytochrome.

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“…No diurnal rhythm could be detected in the transcription of genes coding for either PEPc or the cytosolic form of aldolase. Gehring et al (1977) have reported that Chi a biosynthesis in mustard seedlings also shows circadian rhythmicity, so both the synthesis of the pigment and the apoprotein of the Chi a/b complex are regulated by a circadian rhythm. There is also evidence that both the apoprotein gene expression (Nagy et al, 1988) and Chi a gene expression (Gehring, Kasemir & Mohr, 1977) are regulated by phytochrome.…”

Section: Organismsmentioning

confidence: 99%

“…Gehring et al (1977) have reported that Chi a biosynthesis in mustard seedlings also shows circadian rhythmicity, so both the synthesis of the pigment and the apoprotein of the Chi a/b complex are regulated by a circadian rhythm. There is also evidence that both the apoprotein gene expression (Nagy et al, 1988) and Chi a gene expression (Gehring, Kasemir & Mohr, 1977) are regulated by phytochrome. The circadian rhythm in the expression of the cab gene in tomato leaves is regulated by light to dark and dark to light transitions , and by changes in temperature (Piechulla & Reisselmann, 1990).…”

Section: Organismsmentioning

confidence: 99%

Tansley Review No. 37 Circadian rhythms: their origin and control

Wilkins

1992

New Phytologist

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SUMMARY This article reviews the circadian rhythm of carbon dioxide metabolism in leaves of the Crassulacean plant Bryophyllum (Kalanchoë) fedtsckenkoi which persists both in continuous darkness and a CO2‐free atmosphere, and in continuous light and normal air. Under both conditions the rhythm is due to the periodic activity of the enzyme phosphoenolpyruvate carboxylase (PEPc). The physiological characteristics of the rhythm are described in detail and, from these characteristics, hypotheses are advanced to account for both the generation of the rhythm and the regulation of its phase and period by environmental factors. The periodic activity of PEPc is ascribed to the periodic accumulation of an allosteric inhibitor, malate, in the cytoplasm and its subsequent removal either to the vacuole in continuous darkness, or by metabolism in continuous light. Also involved in the generation of the rhythm is a periodic change in the sensitivity of PEPc to malate inhibition due to the periodic phosphorylation and dephosphorylation of PEPc which changes its K1 by a factor of 10 from 30 to 0.3 mM and vice versa. This periodic phosphorylation of PEPc is apparently achieved by the periodic synthesis and breakdown of a PEPc kinase which phosphorylates the enzyme on a serine residue; dephosphorylation is achieved by a type 2A phosphatase which shows no rhythmic variation. The induction of phase shifts in the rhythm in continuous darkness and CO2‐free air has been explained in terms of light and high‐temperature activated gates or channels in the tonoplast which, when open, allow malate to diffuse between the vacuole and cytoplasm. For the rhythm in continuous light and normal air phase, control by environmental signals can be attributed to changes in the malate levels in critical cell compartments, or in particular cell populations such as the stomatal guard cells, due to regulation of the malate synthesizing enzyme system involving PEPc, and malic enzyme which is responsible for malate metabolism. The role of the stomata in the generation of the rhythm is also discussed. The biochemical events which appear to give rise to the well‐studied circadian rhythms in leaf movement in Samanea and Albizza, in luminescence in Gonyaulax polyedra and in the synthesis of the chlorophyll a/b binding protein are also reviewed in an attempt to identify similarities between these events and those involved in the Bryophyllum rhythm. Finally, the somewhat similar nature of the genes apparently responsible for circadian rhythmicity in Neurospora and Drosophila are discussed, and suggestions made for utilizing anti‐sense nucleic acid technology in the further elucidation of the critical biochemical events involved in the basic, temperature‐compensated circadian oscillator in living organisms.

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The capacity of chlorophyll-a biosynthesis in the mustard seedling cotyledons as modulated by phytochrome and circadian rhythmicity

Cited by 36 publications

References 34 publications

The Effect of Heat Shock on Morphogenesis in Barley

The Effect of Heat Shock on Morphogenesis in Barley

Control of Leaf and Stem Growth in Light-grown Pea Seedlings by Two High Irradiance Responses

Tansley Review No. 37 Circadian rhythms: their origin and control

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