Quenching of chlorophyll fluorescence and primary photochemistry in chloroplasts by dibromothymoquinone.
TL;DR: FO and FV are the same type of fluorescence, both emanating from the bulk chlorophyll of Photosystem II, according to simple theory, which predicts that the ratio FV/FM should equal phipo.
About: This article is published in Biochimica et Biophysica Acta.The article was published on 1975-01-31. It has received 933 citations till now. The article focuses on the topics: Dibromothymoquinone & Quenching (fluorescence).
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TL;DR: In this article, the quantum yield of non-cyclic electron transport was found to be directly proportional to the product of the photochemical fluorescence quenching (qQ) and the efficiency of excitation capture by open Photosystem II (PS II) reaction centres (Fv/Fm).
7,821 citations
TL;DR: Determinations of the photon yield of O2 evolution and the Fv/FM, 692 ratio can serve as excellent quantitative measures of photoinhibition of overall photosynthetic energy-conversion system and of photochemistry of photosystem II, respectively.
Abstract: Photon yields of oxygen evolution at saturating CO2 were determined for 44 species of vascular plants, representing widely diverse taxa, habitats, life forms and growth conditions. The photonyield values on the basis of absorbed light (φa) were remarkably constant among plants possessing the same pathway of photosynthetic CO2 fixation, provided the plants had not been subjected to environmental stress. The mean φa value ±SE for 37 C3 species was 0.106±0.001 O2·photon-1. The five C4 species exhibited lower photon yields and greater variation than the C3 species (φa=0.0692±0.004). The φa values for the two Crassulaceanacid-metabolism species were similar to those of C3 species. Leaf chlorophyll content had little influence on φa over the range found in normal, healthy leaves. Chlorophyll fluorescence characteristics at 77 K were determined for the same leaves as used for the photon-yield measurements. Considerable variation in fluorescence emission both at 692 nm and at 734 nm, was found 1) among the different species; 2) between the upper and lower surfaces of the same leaves; and 3) between sun and shade leaves of the same species. By contrast, the ratio of variable to maximum fluorescence emission at 692 nm (Fv/FM, 692) remained remarkably constant (The mean value for the C3 species was 0.832±0.004). High-light treatments of shade leaves resulted in a reduction in both φa and the Fv/FM, 692 ratio. The extent of the reductions increased with time of exposure to bright light. A linear relationship was obtained when φa was plotted against Fv/FM, 692. The results show that determinations of the photon yield of O2 evolution and the Fv/FM, 692 ratio can serve as excellent quantitative measures of photoinhibition of overall photosynthetic energy-conversion system and of photochemistry of photosystem II, respectively. This is especially valuable in field work where it is often impossible to obtain appropriate controls.
2,287 citations
Cites background from "Quenching of chlorophyll fluorescen..."
...On the basis of a model of chlorophyll fluorescence at 77 K, Kitajima and Butler (1975) derived the expression q~p = Fv/FM where q~p is the photochemical efficiency of PSII....
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...The ratio of variable to maximum PSII fluorescence, FV/FM, 692, is thought to be a direct measure of efficiency of the primary photochemistry of PSII (see Kitajima and Butler 1975 for the theoretical basis)....
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...Although much new information on the origin of fluorescence emission and the mechanisms of fluorescence quenching has become available since 1975, we see no compelling reason that this new information would substantially alter the above expression of Kitajima and Butler (1975) ....
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...It is especially noteworthy that Kitajima and Butler (1975) proposed, on theoretical grounds, that the ratio of variable to maximum fluorescence (Fv/Fu) emitted from photosystem II (PSII) at 77 K may serve as a quantitative indicator of the efficiency of the photochemistry of PSII....
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TL;DR: The present "renaissance" of chlorophyll fluorescence may be the product of a fruitful dynamic interaction between three different research disciplines, i.e., basic and applied research linked to new developments in instrumentation and methodology.
Abstract: During recent years there has been remarkable progress in the understanding and practical use of chlorophyll fluorescence in plant science. This 'renaissance' of chlorophyll fluorescence was induced by the urgent need of applied research (like plant stress physiology, ecophysiology, phytopathology etc.) for quantitative, non-invasive, rapid methods to assess photosynthesis in intact leaves. Recent developments of suitable instrumentation and methodology have substantially increased these possibilities. Actually, a vast amount of knowledge on chlorophyll fluorescence had already accumulated over more than 50 years, since the discovery of the Kautsky effect in 1931 (Kautsky and Hirsch 1931) (for reviews, see e.g., Lavorel and Etienne 1977, Briantais et al. 1986, Renger and Schreiber 1986). On the one hand this knowledge was mechanistic, resulting from biophysically oriented basic research. On the other hand it was phenomenological, originating from applied plant physiological research. Until recently the phenomenology of whole leaf chlorophyll fluorescence appeared far too complex to find serious attention of biophysicists. Thus, for a long time, there was a gap between applied and basic research in chlorophyll fluorescence. Developments in instrumentation (Ogren and Baker 1985, Schreiber 1986, Schreiber et al. 1986) and methodology (Bradbury and Baker 1981, Krause et al. 1982, Quick and Horton 1984, Dietz et al. 1985, Demmig et al. 1987, Weis and Berry 1987, Bilger et al. 1989, Genty et al. 1989) has succeeded in closing this gap and bringing these two disciplines into sufficiently close contact and in mutually stimulating interaction. Consequently the present "renaissance" of chlorophyll fluorescence may be the product of a fruitful dynamic interaction between three different research disciplines, i.e., basic and applied research linked to new developments in instrumentation and methodology (see scheme in Fig. 1). As a result, measuring chlorophyll fluorescence has become a very attractive means of obtaining rapid, semiquantitative information on photosynthesis, used by an increasing number of researchers not only in the laboratory but also in the field. The wide range of possible applications is reflected by the broad spectrum of contributions to this issue of Photosynthesis Research. The progress made in chlorophyll fluorescence instrumentation and methodology has also induced new developments in the adjacent fields of absorbance spectroscopy (e.g., Klughammer et al. or Harbinson et al. in this issue), photoacoustic spectroscopy (e.g., Canaani, Dau and Hansen, Kolbowski et al. or Snel et al. in this issue) and chlorophyll luminescence (delayed fluorescence) (Bilger and Schreiber in this issue). These new developments are expected to play a role in
2,200 citations
Cites background from "Quenching of chlorophyll fluorescen..."
...Though our knowledge of the mechanisms underlying chlorophyll fluorescence quenching has advanced considerably (Kautsky and Hirsch 1931, Duysens and Sweers 1963, Kitajima and Butler 1975,...
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01 Jun 1996
TL;DR: It is shown how the dynamic properties of the proteins and pigments of the chlorophyll a/b light-harvesting complexes of photosystem II first enable the level of excitation energy to be sensed via the thylakoid proton gradient and subsequently allow excessEnergy to be dissipated as heat by formation of a nonphotochemical quencher.
Abstract: When plants are exposed to light intensities in excess of those that can be utilized in photosynthetic electron transport, nonphotochemical dissipation of excitation energy is induced as a mechanism for photoprotection of photosystem II. The features of this process are reviewed, particularly with respect to the molecular mechanisms involved. It is shown how the dynamic properties of the proteins and pigments of the chlorophyll a/b light-harvesting complexes of photosystem II first enable the level of excitation energy to be sensed via the thylakoid proton gradient and subsequently allow excess energy to be dissipated as heat by formation of a nonphotochemical quencher. The nature of this quencher is discussed, together with a consideration of how the variation in capacity for energy dissipation depends on specific features of the composition of the light-harvesting system. Finally, the prospects for future progress in understanding the regulation of light harvesting are assessed.
1,786 citations
TL;DR: Synthese des mecanismes de photoprotection chez les vegetaux, en reponse a un eclairement energetique; implication des carotenoides, en particulier la zeaxanthine, a la dissipation d'energie, en relation avec le cycle des xanthophylles.
1,555 citations
References
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TL;DR: A simple photochemical model for the photosynthetic units of Photosystem II based on first-order rate constants for de-excitation of excited chlorophyll molecules is presented in the form of equations which predict the yields of fluorescence.
334 citations
TL;DR: Experiments with the tris-washed chloroplasts indicated that electron donors preferentially donate electrons to photosystem II but in the presence of DCMU the donors (with the exception of PD at low concentrations) could also supply electrons after the DCMU block.
Abstract: The artificial electron donor compounds p-phenylenediamine (PD), N, N, N′, N′-tetramethyl-p-phenylenediamine (TMPD), and 2,6-dichlorophenol-indophenol (DCPIP) restored the Hill reaction and photophosphorylation in chloroplasts that had been inhibited by washing with 0.8 m tris (hydroxymethyl) aminomethane (tris) buffer, pH 8.0. The tris-wash treatment inhibited the electron transport chain between water and photosystem II and electron donation occurred between the site of inhibition and photosystem II. Photoreduction of nicotinamide adenine dinucleotide phosphate (NADP) supported by 33 μm PD plus 330 μm ascorbate was largely inhibited by 1 μm 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) while that supported by 33 μm TMPD or DCPIP plus ascorbate was relatively insensitive to DCMU. Experiments with the tris-washed chloroplasts indicated that electron donors preferentially donate electrons to photosystem II but in the presence of DCMU the donors (with the exception of PD at low concentrations) could also supply electrons after the DCMU block. The PD-supported photoreduction of NADP showed the relative inefficiency in far-red light characteristic of chloroplast reactions requiring photosystem II. With phosphorylating systems involving electron donors at low concentrations (33 μm donor plus 330 μm ascorbate) photophosphorylation, which occurred with P/e2 ratios approaching unity, was completely inhibited by DCMU but with higher concentrations of the donor systems, photophosphorylation was only partially inhibited.
287 citations
132 citations
TL;DR: The kinetics of fluorescence quenching at different light intensities and concentrations of quencher and absence of stimulation of O 2 evolution indicate that the quenchers do not stimulate photosynthetic electron transport but interact directly with chlorophyll molecules of photosystem 2 by formation of traps for the excitation energy.
77 citations
TL;DR: The lifetime‐incident intensity relationship for Chlorella and chloroplast fragments is quantitatively similar to the incident‐intensity dependence of fluorescence yield and oxygen evolution and thus supports the hypothesis that these three measuring variables are controlled by the concentration of ‘open’ trapping systems.
Abstract: — Phase-fluorometer measurements of the fluorescence lifetime, τ, from chlorophyll in Chlorella, Bishop's 8 and 11 Scenedesmus mutants, sugarbeet leaf and chloroplast fragments demonstrate that: τ is independent of modulation frequency at 27 and 14 mc. in the experimental-wavelength range from 650 to 735 nm (with blue or blue-green excitation); with Chlorelfa and chloroplast fragments τ rises hyperbolically with intensity to τmax about 2 nsec and 0·7 nsec respectively; DCMU poisoned Chlorella and sugarbeet leaf as well as the mutants have τ values near 2 nsec; the lifetime-incident intensity relationship for Chlorella and chloroplast fragments is quantitatively similar to the incident-intensity dependence of fluorescence yield and oxygen evolution and thus supports the hypothesis that these three measuring variables are controlled by the concentration of ‘open’ trapping systems; τ is independent of emission wave-length to suggest that fluorescence is dominated by a single chlorophyll species. The reaction velocity-lifetime correlation indicates that fluorescence behavior is directly controlled by system II.
61 citations