Phytochrome-mediated changes in the membrane potential of subepidermal cells of Lemna paucicostata 6746

Löppert, H. G.; Kronberger, Winfried; Kandeler, Riklef

doi:10.1007/bf00391169

Cited by 24 publications

(6 citation statements)

References 15 publications

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“…These changes have half-times compatible with those of membrane potential transients. The possibility of such reactions must be considered in explaining our results, as well as those of Loppert et al (14) for Lemna. Regardless of the pigment system involved, the FR-stimulated potential change could be significant in transducing the R/FR ratio of ambient light into a change in membrane properties. The FR-induced depolarization represents only a small fraction of the total light-on reaction in white light.…”

Section: Far-red Light and Intracellular Potentials Resultssupporting

confidence: 58%

“…Correlation (or lack of agreement) with known photosynthetic processes is not enough to understand transient membrane effects. The use (14) of DCMU to inhibit overall photosynthesis does not rule out participation ofphotosynthetic pigments (herbicide bleached Lemna might be better). Red and FR light cause changes in redox state ofa Cyt in a Lemna mutant in which noncyclic electron transport is blocked just after PSII (22).…”

Section: Far-red Light and Intracellular Potentials Resultsmentioning

confidence: 99%

“…In Samanea, R shifts the potential to a more negative value, and FR restores the previous level. In light-grown Lemna treated with DCMU to block noncyclic electron flow, R alone has no effect, FR shifts the potential to a more negative value, and R after FR restores the resting potential (14). R and FR interact in the light-induced membrane depolarization in Nitella (26).…”

mentioning

confidence: 94%

“…In pulvinar motor cells of (light-grown) Samanea (21) and in subepidermal cells of green Lemna (14), R and FR reversible potential changes have been recorded with intracellular electrodes. In Samanea, R shifts the potential to a more negative value, and FR restores the previous level.…”

mentioning

confidence: 99%

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Far-Red Light-Induced Changes in Intracellular Potentials of Spinach Mesophyll Cells

Montavon¹,

Horwitz²,

Greppin³

1983

Plant Physiol.

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In green plants, the large bioelectric changes that photosynthetically active light stimulates make it difficult to observe electrical potential changes related to phytochrome photoconversion. As a first step towards distinguishing between photosynthetic and phytochrome effects, we showed that red light enhances far-red stimulated intracellular potential changes in spinach (Spinacia oleracca) leaf mesophyll cells.For a dark-adapted leaf, the response to far-red light increased during the first 10 to 30 exposures of 2.5 minutes, after which it was constant. The intracellular potential depolarized by an average of 0.3 millivolts during each 2.5-minute far-red light period, and returned to the resting value during each subsequent dark period. Continuous supplementary red light (at 1-5% of the fluence rate of the far-red light that stimulated the depolarizations) increased the response to far-red 2-to 3-fold. Supplementary red light did not amplify the response to alternating 702 nanometers light and dark periods. The Emerson enhancement effect thus does not seem to explain amplification of the response to 730 nanometers light by supplementary red light. This does not prove that photosynthetic pigments are not involved in some other way.

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Section: Far-red Light and Intracellular Potentials Resultssupporting

confidence: 58%

Section: Far-red Light and Intracellular Potentials Resultsmentioning

confidence: 99%

mentioning

confidence: 94%

mentioning

confidence: 99%

See 2 more Smart Citations

Far-Red Light-Induced Changes in Intracellular Potentials of Spinach Mesophyll Cells

Montavon¹,

Horwitz²,

Greppin³

1983

Plant Physiol.

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“…Interactions between D-usnic acid and phytochrome as effectors ofdehydrogenase could be regarded as a process offacilitated diffusion of D-usnic acid affected by Pfr, since changes in membrane permeability produced by Pfr are today well documented (1,1,15). This action is confirmed by the measurements of remaining phenol in the media.…”

Section: Discussionmentioning

confidence: 83%

Equivalence between Pfr and Cyclic AMP in the Induction of d-Usnic Acid Dehydrogenase in the Lichen Evernia prunastri

Avalos

Vicente²

1987

Plant Physiol.

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D-Usnic acid dehydrogenase is induced in Evernia prunastri thalli by a supply of exogenous D-usnic acid in light. This effect is enhanced by red light pulses through a two step way: a very rapid increase of activity after the first 10 minutes of red light, which is not reversed by far-red light, and a slow enhancement following successive red light pulses at the beginning of each hour of incubation. The last response is completely reversed by far-red following red light. Although induction of the enzyme is not achieved in the dark, 0.1 and 0.5 millimolar cyclic AMP, or 0.1 millimolar dibutyryl cyclic AMP substitutes light action and, then, the enzyme is produced. In addition, phytochrome-far red-absorbing formincreases the amount of endogenously produced cyclic AMP and this effect is shown to be photoreversible when ethylenediaminetetraacetic acid is inhibiting adenylate cyclase.The plant photoreceptor phytochrome mediates a large number ofdevelopmental responses to light and, thus, it must regulate an orderly sequence of changes in enzyme activities. There is strong evidence to support the hypothesis that phytochrome enhances the rate of de novo production of some enzymes (18) by controlling the concentrations of specific messenger RNA populations (6), even its own translatable phytochrome mRNA (3). This has been deduced from the use of protein synthesis inhibitors that impede nuclear gene expression as well as cytoplasmic protein synthesis (4, 23). However, alternative effects of phytochrome must be supposed since, in some situations, changes in the amount and proportion of RNA polymerases have not been observed during illumination (24). In addition, the total amount of some enzymes (active + inactive forms of ascorbate oxidase) does not change after illumination (19), as revealed by immunochemical assay. However, enzyme activity increases rapidly after 30 h FR.2 Thus, phytochrome regulation of this enzyme activity must occur at a post-transciptional level.Concerning lichen metabolism and development, the concentration of lichen acids is enhanced by light (2), although phytochrome has never been related to this process or to the synthesis or activation of enzymes. The lichen Evernia prunastri accumulates one of the acid phenols, D-usnic acid, which can be metabolized by an inducible D-usnic acid dehydrogenase (Fig. 1), whose activity develops only after illumination (27 In this work, we attempt to probe the involvement of phytochrome in the reduction of D-usnic acid in E. prunastri and to study the mechanism involved in this process. MATERIALS AND METHODSEvernia prunastri (L) Ach., growing on Quercus pyrenaica Lam., was collected in Valsain (Segovia, Spain), dried in air at room temperature, and stored in polyethylene bags at 7°C in the dark until required. Samples of 1.0 g dry weight were maintained in the dark, at 26°C for 48 h before incubation. Then, they were floated on 25 ml of 35 uM D-usnic acid in 2% sodium bicarbonate, at pH 8.0, in the dark or in light, at 26°C. Where indicated, 0.1 mm cycl...

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Phytochrome Control of Root Growth Rate in Lemna Species

Chamuris

Nielsen

1983

American J of Botany

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Root growth rate was studied in Lemna gibba L. (strains Gl and G3) and L. minor L. in relation to low energy red and far‐red light treatments. Far‐red treatments inhibited growth rate; inhibition was abolished upon subsequent treatment with red light. These effects can be observed after an 18‐hr growth period. This red/far‐red photoreversible response suggests that root growth in L. gibba L. and L. minor L. is under phytochrome control.

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Phytochrome-mediated changes in the membrane potential of subepidermal cells of Lemna paucicostata 6746

Cited by 24 publications

References 15 publications

Far-Red Light-Induced Changes in Intracellular Potentials of Spinach Mesophyll Cells

Far-Red Light-Induced Changes in Intracellular Potentials of Spinach Mesophyll Cells

Equivalence between Pfr and Cyclic AMP in the Induction of d-Usnic Acid Dehydrogenase in the Lichen Evernia prunastri

Phytochrome Control of Root Growth Rate in Lemna Species

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