Light Inhibition Of Respiration Research Articles

The Kok effect revisited.

Summary The Kok effect refers to the abrupt decrease around the light compensation point in the slope of net photosynthetic rate vs irradiance. Arguably, this switch arises from light inhibition of respiration, allowing the Kok method to estimate day respiration (R d). Recent analysis suggests that increasing proportions of photorespiration (quantified as Γ*/C c, the ratio of CO2 compensation point Γ* to chloroplast CO2 concentration, C c) with irradiance explain much of the Kok effect. Also, the Kok method has been modified to account for the decrease in PSII photochemical efficiency (Φ2) with irradiance.Using a model that illustrates how varying R d, Γ*/C c, Φ2 and proportions of alternative electron transport could engender the Kok effect, we quantified the contribution of these parameters to the Kok effect measured in sunflower across various O2 and CO2 concentrations and various temperatures.Overall, the decreasing Φ2 with irradiance explained c. 12%, and the varying Γ*/C c explained c. 25%, of the Kok effect. Maximum real light inhibition of R d was much lower than the inhibition derived from the Kok method, but still increased with photorespiration.Photorespiration had a dual contribution to the Kok effect, one via the varying Γ*/C c and the other via its participation in light inhibition of R d.

Environmental controls on light inhibition of respiration and leaf and canopy daytime carbon exchange in a temperate deciduous forest.

Uncertainty in the estimation of daytime ecosystem carbon cycling due to the light inhibition of leaf respiration and photorespiration, and how these small fluxes vary through the growing season in the field, remains a confounding element in calculations of gross primary productivity and ecosystem respiration. Our study focuses on how phenology, short-term temperature changes and canopy position influence leaf-level carbon exchange in Quercus rubra L. (red oak) at Harvard Forest in central Massachusetts, USA. Using leaf measurements and eddy covariance, we also quantify the effect of light inhibition on estimates of daytime respiration at leaf and ecosystem scales. Measured rates of leaf respiration in the light and dark were highest in the early growing season and declined in response to 10-day prior air temperatures (P < 0.01), evidence of within-season thermal acclimation. Leaf respiration was significantly inhibited by light (27.1 ± 2.82% inhibited across all measurements), and this inhibition varied with the month of measurement; greater inhibition was observed in mid-summer leaves compared with early- and late-season leaves. Increases in measurement temperature led to higher rates of respiration and photorespiration, though with a less pronounced positive effect on photosynthesis; as a result, carbon-use efficiency declined with increasing leaf temperature. Over the growing season when we account for seasonally variable light inhibition and basal respiration rates, our modeling approaches found a cumulative 12.9% reduction of leaf-level respiration and a 12.8% reduction of canopy leaf respiration, resulting in a 3.7% decrease in total ecosystem respiration compared with estimates that do not account for light inhibition in leaves. Our study sheds light on the environmental controls of the light inhibition of daytime leaf respiration and how integrating this phenomenon and other small fluxes can reduce uncertainty in current and future projections of terrestrial carbon cycling.

Bringing the Kok effect to light: A review on the integration of daytime respiration and net ecosystem exchange

Net ecosystem exchange (NEE) represents the difference between carbon assimilated through photosynthesis, or gross primary productivity (GPP), and carbon released via ecosystem respiration (ER). NEE, measured via eddy covariance and chamber techniques, must be partitioned into these fluxes to accurately describe and understand the carbon dynamics of an ecosystem. GPP and daytime ER may be significantly overestimated if the light inhibition of foliar mitochondrial respiration, or “Kok effect,” is not accurately estimated and further integrated into ecosystem measurements. The light inhibition of respiration, a composite effect of multiple cellular pathways, is reported to cause between 25‐100% inhibition of foliar mitochondrial respiration, and for this reason needs to be considered when estimating larger carbon fluxes. Partitioning of respiration between autotrophic and heterotrophic respiration, and applying these scaled respiratory fluxes to the ecosystem‐level proves to be difficult, and the integration of light inhibition into single and continuous measures of ecosystem respiration will require new interpretations and analysis of carbon exchange in terrestrial ecosystems.

Light inhibition of respiration is due to a dual function of the cytochrome b6- f complex and the plastocyanin/ cytochrome c-553 pool in Aphanocapsa

Studies of the respiratory electron transport pathway in the blue-green alga, Aphanocapsa, demonstrated the presence of cytochrome oxidase and a Cytochrome complex. The use of antimycin A showed only the occurrence of a plastidal type of cytochrome complex (the cytochrome b 6- f complex), which is insensitive to this inhibitor. Determination of the extent of photooxidation of cytochromes c-553 and f-556 under conditions of high and low cytochrome oxidase activities indicated an electron flow through both cytochromes to cytochrome oxidase. Direct evidence for a common segment of photosynthetic and respiratory electron transport from plastoquinone via the cytochrome b 6- f complex to the soluble plastocyanin/cytochrome c-553 pool, as well as a competition between cytochrome oxidase and Photosystem I for reductants in this pool in the light, was obtained by measurements of electron transport with suitable electron donors in this alga.

Interaction between the respiratory and photosynthetic electron transport chains of intact cells of Rhodopseudomonas capsulata mediated by membrane potential.

1. The inhibition of respiration by light and the relief from this inhibition by uncoupling agents have been studied in intact cells of Rhodopseudomonas capsulata. 2. The same concentration range of carbonylcyanide p-trifluoromethoxyphenylhydrazone [CF3OPhzC(CN)2] prevented light-inhibition of respiration and depressed the membrane potential (delta psi) in illuminated, aerobic bacterial suspensions. 3. For a wide range of CF3OPhzC(CN)2 concentration the dependence of the respiration rate on delta psi in darkened cells coincided with that in illuminated cells. 4. When present separately, antimycin A and low concentrations of CF3OPhzC(CN)2 had little effect on light-inhibition of respiration or on delta psi in illuminated, aerobic cells, but added together they gave relief from light-inhibition and they lowered delta psi. 5. In the absence of CF3OPhzC(CN)2 even very low light intensities were sufficient to inhibit respiration and increase delta psi. In the presence of CF3OPhzC(CN)2 much higher light intensities were necessary. 6. The results are interpreted as evidence that light-inhibition of respiration is mediated by delta psi. The modification of the response by uncouplers, inhibitors and with light intensity is critically determined by the ionic conductance properties of the membrane in accordance with the findings in [Clark, A.J., Cotton, N.P.J., and Jackson, J.B. (1983) Eur. J. Biochem. 130, 575-580].

Light inhibition of respiration in Halobacterium halobium

FEBS LettersVolume 36, Issue 1 p. 72-76 Full-length articleFree Access Light inhibition of respiration in Halobacterium halobium Dieter Oesterhelt, Dieter Oesterhelt Institut für Biochemie der Universität München, 8 München 2, Karlstrasse 23, W. Germany Max-Planck-Institut für Biochemie, 8033 Martinsried bei München, W. GermanySearch for more papers by this author Dieter Oesterhelt, Dieter Oesterhelt Institut für Biochemie der Universität München, 8 München 2, Karlstrasse 23, W. Germany Max-Planck-Institut für Biochemie, 8033 Martinsried bei München, W. GermanySearch for more papers by this author First published: October 01, 1973 https://doi.org/10.1016/0014-5793(73)80339-4Citations: 55AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume36, Issue1October 01, 1973Pages 72-76 ReferencesRelatedInformation

The adjustment of photosynthetically grown cells of Rhodospirillum rubrum to aerobic light conditions

The growth of photosynthetically precultured cells of Rhodospirillum rubrum under aerobic condition in light is investigated. Special emphasis is given to the question of whether the photosynthetic electron transport chain is influenced under these conditions. Light-induced absorbance changes under anaerobic conditions show that although in whole cells a variation can be noted, the reactions of isolated membranes decrease only very slowly and parallel to each other. The photophosphorylation activity remains constant on a bacteriochlorophyll basis. On a cell mass basis this activity decreases parallel to the decreasing bacteriochlorophyll content. Light-dependent NAD+ reduction by ascorbate-DCPI remains constant on a bacteriochlorophyll basis, whereas succinate supported NAD+ reduction in light increases. On a cell mass basis the activity of succinate supported NAD+ reduction stays nearly constant, thus showing similar responses to the presence of oxygen in light as the NADH oxidase system. NADH oxidase activity increases on a bacteriochlorophyll basis and does not change on a cell mass basis. Parallel to the NADH-oxidase system, oxygen uptake in the dark by whole cells does not change after aerobiosis in light. Light inhibits respiration even after several generations of growth in the presence of oxygen; however, the inhibition decreases slowly. Light inhibition of respiration can be totally overcome by the addition of the uncoupler CCCP. These results indicate that light-dependent electron transport is not influenced significantly by the presence of oxygen. Although the respiratory system is formed, cells preferentially grow photosynthetically. Respiration takes over when the amount of bacteriochlorophyll reaches very low values.