Transcriptional regulation of photoprotection in dark-to-light transition - more than just a matter of excess light energy

In nature, photosynthetic organisms are exposed to different light spectra and intensities depending on the time of day and atmospheric and environmental conditions. When photosynthetic cells absorb excess light, they induce non-photochemical quenching to avoid photo-damage and trigger expression of photoprotective genes. In this work, we used the green alga Chlamydomonas reinhardtii to assess the impact of light intensity, light quality, wavelength, photosynthetic electron transport and CO2 on induction of the photoprotective genes (LHCSR1, LHCSR3 and PSBS) during dark-to-light transitions. Induction (mRNA accumulation) occurred at very low light intensity, was independently modulated by blue and UV-B radiation through specific photoreceptors, and only LHCSR3 was strongly controlled by CO2 levels through a putative enhancer function of CIA5, a transcription factor that controls genes of the carbon concentrating mechanism. We propose a model that integrates inputs of independent signaling pathways and how they may help the cells anticipate diel conditions and survive in a dynamic light environment.

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The role of LHCBM1 in non-photochemical quenching in Chlamydomonas reinhardtii

10.1101/2022.01.13.476201 ◽

2022 ◽

Author(s):

Xin Liu ◽

Wojciech J Nawrocki ◽

Roberta Croce

Keyword(s):

Chlamydomonas Reinhardtii ◽

Protein Complexes ◽

Ph Sensor ◽

High Light ◽

Photochemical Quenching ◽

Knock Out ◽

Photosynthetic Organisms ◽

Pigment Protein Complexes ◽

Non Photochemical Quenching

Non-photochemical quenching (NPQ) is the process that protects photosynthetic organisms from photodamage by dissipating the energy absorbed in excess as heat. In the model green alga Chlamydomonas reinhardtii, NPQ was abolished in the knock-out mutants of the pigment-protein complexes LHCSR3 and LHCBM1. However, while LHCSR3 was shown to be a pH sensor and switching to a quenched conformation at low pH, the role of LHCBM1 in NPQ has not been elucidated yet. In this work, we combine biochemical and physiological measurements to study short-term high light acclimation of npq5, the mutant lacking LHCBM1. We show that while in low light in the absence of this complex, the antenna size of PSII is smaller than in its presence, this effect is marginal in high light, implying that a reduction of the antenna is not responsible for the low NPQ. We also show that the mutant expresses LHCSR3 at the WT level in high light, indicating that the absence of this complex is also not the reason. Finally, NPQ remains low in the mutant even when the pH is artificially lowered to values that can switch LHCSR3 to the quenched conformation. It is concluded that both LHCSR3 and LHCBM1 need to be present for the induction of NPQ and that LHCBM1 is the interacting partner of LHCSR3. This interaction can either enhance the quenching capacity of LHCSR3 or connect this complex with the PSII supercomplex.

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Inhibition of non-photochemical quenching increases functional absorption cross-section of photosystem II as excitation from closed reaction centres is transferred to open centres, facilitating earlier light saturation of photosynthetic electron transport

Functional Plant Biology ◽

10.1071/fp20347 ◽

2021 ◽

Author(s):

Charles Barry Osmond ◽

Wah Soon Chow ◽

Sharon A. Robinson

Keyword(s):

Electron Transport ◽

Photosystem Ii ◽

Cross Section ◽

Absorption Cross Section ◽

Photosynthetic Electron Transport ◽

Photochemical Quenching ◽

Absorption Cross ◽

Light Saturation ◽

Reaction Centres ◽

Non Photochemical Quenching

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Structural Changes and Non-Photochemical Quenching of Chlorophyll a Fluorescence in Oxygenic Photosynthetic Organisms

Advances in Photosynthesis and Respiration - Non-Photochemical Quenching and Energy Dissipation in Plants, Algae and Cyanobacteria ◽

10.1007/978-94-017-9032-1_16 ◽

2014 ◽

pp. 343-371 ◽

Cited By ~ 2

Author(s):

Győző Garab

Keyword(s):

Chlorophyll A ◽

Chlorophyll A Fluorescence ◽

Structural Changes ◽

Photochemical Quenching ◽

Photosynthetic Organisms ◽

Non Photochemical Quenching

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Responses of Rainforest Understorey Plants to Excess Light during Sunflecks

Functional Plant Biology ◽

10.1071/pp96074 ◽

1997 ◽

Vol 24 (1) ◽

pp. 17 ◽

Cited By ~ 32

Author(s):

Jenny R. Watling ◽

Sharon A. Robinson ◽

Ian E. Woodrow ◽

C. Barry Osmond

Keyword(s):

Tropical Rainforest ◽

Photon Flux ◽

Photochemical Quenching ◽

Photon Flux Density ◽

Leaf Angle ◽

Low Light ◽

Fourth Species ◽

Excess Light ◽

Understorey Plants ◽

Non Photochemical Quenching

Responses of Alocasia macrorrhiza (L.) G. Don, Castanospora alphandii (F. Muell.) F. Muell. and Alpinia hylandii R. Smith, growing in a tropical rainforest understorey, to excess light during sunflecks were investigated using chlorophyll fluorescence techniques and by analysing xanthophyll cycle activity. A fourth species, the pioneerOmalanthus novo-guineensis (Warb.) Schum., growing in a small gap, was also studied. In all three understorey species there were large and rapid decreases in the proportion of open Photosystem II (PSII) centres, as indicated by qP, on illumination with saturating light and a concurrent increase in non-photochemical quenching. qP remained low (< 0.4) throughout the period of illumination (~15 min), although it did increase gradually, probably reflecting photosynthetic induction. Sustained declines (up to 120 min) in quantum yield, indicated by Fv/Fm, occurred in all three understorey species following exposure to saturating Photon flux density (PFD) during sunflecks. When ?PSII was monitored during sunflecks it was found to be very sensitive to changes in PFD, declining rapidly with even modest rises in the latter. There was rapid and continuing net conversion of violaxanthin (V) to antheraxanthin plus zeaxanthin (A+Z) on exposure of A. macrorrhiza and C. alphandii to saturating sunflecks. On returning to low light A. macrorrhiza retained its high levels of A+Z for up to 60 min, while C. alphandii rapidly converted back to V. O. novo- guineensis responded to high light by changing its leaf angle to reduce interception and showed no indication of photoinhibition during or after exposure.

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An optimised method for correcting quenched fluorescence yield

Ocean Science Discussions ◽

10.5194/osd-11-1243-2014 ◽

2014 ◽

Vol 11 (3) ◽

pp. 1243-1264 ◽

Cited By ~ 3

Author(s):

L. Biermann ◽

C. Guinet ◽

M. Bester ◽

A. Brierley ◽

L. Boehme

Keyword(s):

Light Intensity ◽

Southern Ocean ◽

Fluorescence Emission ◽

Euphotic Zone ◽

Fluorescence Yield ◽

High Light Intensity ◽

High Light ◽

Photochemical Quenching ◽

Non Photochemical Quenching

Abstract. Under high light intensity, phytoplankton protect their photosystems from bleaching through non-photochemical quenching processes. The consequence of this is suppression of fluorescence emission, which must be corrected when measuring in situ yield with fluorometers. Previously, this has been done using the limit of the mixed layer, assuming that phytoplankton are uniformly mixed from the surface to this depth. However, the assumption of homogeneity is not robust in oceanic regimes that support deep chlorophyll maxima. To account for these features, we correct from the limit of the euphotic zone, defined as the depth at which light is at ~1% of the surface value. This method was applied to fluorescence data collected by eleven animal-borne fluorometers deployed in the Southern Ocean over four austral summers. Six tags returned data showing evidence of deep chlorophyll features. Using the depth of the euphotic layer, quenching was corrected without masking subsurface fluorescence signals.

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The Endosymbiotic Coral Algae Symbiodiniaceae Are Sensitive to a Sensory Pollutant: Artificial Light at Night, ALAN

Frontiers in Physiology ◽

10.3389/fphys.2021.695083 ◽

2021 ◽

Vol 12 ◽

Author(s):

Inbal Ayalon ◽

Jennifer I. C. Benichou ◽

Dror Avisar ◽

Oren Levy

Keyword(s):

Cell Cultures ◽

Marine Ecosystem ◽

Photochemical Quenching ◽

Artificial Light ◽

Light At Night ◽

Symbiotic Algae ◽

Light Spectra ◽

Clade C ◽

Low Levels ◽

Non Photochemical Quenching

Artificial Light at Night, ALAN, is a major emerging issue in biodiversity conservation, which can negatively impact both terrestrial and marine environments. Therefore, it should be taken into serious consideration in strategic planning for urban development. While the lion’s share of research has dealt with terrestrial organisms, only a handful of studies have focused on the marine milieu. To determine if ALAN impacts the coral reef symbiotic algae, that are fundamental for sustainable coral reefs, we conducted a short experiment over a period of one-month by illuminating isolated Symbiodiniaceae cell cultures from the genera Cladocopium (formerly Clade C) and Durusdinium (formerly Clade D) with LED light. Cell cultures were exposed nightly to ALAN levels of 0.15 μmol quanta m–2 s–1 (∼4–5 lux) with three light spectra: blue, yellow and white. Our findings showed that even in very low levels of light at night, the photo-physiology of the algae’s Electron Transport Rate (ETR), Non-Photochemical Quenching, (NPQ), total chlorophyll, and meiotic index presented significantly lower values under ALAN, primarily, but not exclusively, in Cladocopium cell cultures. The findings also showed that diverse Symbiodiniaceae types have different photo-physiology and photosynthesis performances under ALAN. We believe that our results sound an alarm for the probable detrimental effects of an increasing sensory pollutant, ALAN, on the eco-physiology of symbiotic corals. The results of this study point to the potential effects of ALAN on other organisms in marine ecosystem such as fish, zooplankton, and phytoplankton in which their biorhythms is entrained by natural light and dark cycles.

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Shade lichens are characterized by rapid relaxation of non-photochemical quenching on transition to darkness

The Lichenologist ◽

10.1017/s0024282921000323 ◽

2021 ◽

Vol 53 (5) ◽

pp. 409-414

Author(s):

Richard P. Beckett ◽

Farida V. Minibayeva ◽

Kwanele W. G. Mkhize

Keyword(s):

Chlorophyll Fluorescence ◽

Quantum Yield ◽

Light Energy ◽

Photochemical Quenching ◽

Photosynthetic Organisms ◽

Light Levels ◽

Lower Light ◽

Optimal Productivity ◽

Sun And Shade ◽

Non Photochemical Quenching

AbstractNon-photochemical quenching (NPQ) plays an important role in protecting photosynthetic organisms from photoinhibition by dissipating excess light energy as heat. However, excess NPQ can greatly reduce the quantum yield of photosynthesis at lower light levels. Recently, there has been considerable interest in understanding how plants balance NPQ to ensure optimal productivity in environments in which light levels are rapidly changing. In the present study, chlorophyll fluorescence was used to study the induction and relaxation of non-photochemical quenching (NPQ) in the dark and the induction of photosynthesis in ten species of lichens, five sampled from exposed and five sampled from shaded habitats. Here we show that the main difference between sun and shade lichens is the rate at which NPQ relaxes in the dark, rather than the speed that photosynthesis starts upon illumination. During the first two minutes in the dark, NPQ values in the five sun species declined only by an average of 2%, while by contrast, in shade species the average decline was 40%. For lichens growing in microhabitats where light levels are rapidly changing, rapid relaxation of NPQ may enable their photobionts to use the available light most efficiently.

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Both Multi-Segment Light Intensity and Extended Photoperiod Lighting Strategies, with the Same Daily Light Integral, Promoted Lactuca sativa L. Growth and Photosynthesis

Agronomy ◽

10.3390/agronomy9120857 ◽

2019 ◽

Vol 9 (12) ◽

pp. 857 ◽

Cited By ~ 1

Author(s):

Hanping Mao ◽

Teng Hang ◽

Xiaodong Zhang ◽

Na Lu

Keyword(s):

Quantum Yield ◽

Light Intensity ◽

Plant Growth ◽

Light Stress ◽

Photochemical Quenching ◽

Daily Light Integral ◽

Weak Light ◽

Research On Application ◽

Non Photochemical Quenching ◽

Light Integral

With the rise of plant factories around the world, more and more crops are cultivated under artificial light. Studies on effects of lighting strategies on plant growth, such as different light intensities, photoperiods, and their combinations, have been widely conducted. However, research on application of multi-segment light strategies and associated plant growth mechanisms is still relatively lacking. In the present study, two lighting strategies, multi-segment light intensity and extended photoperiod, were compared with a constant light intensity with a 12 h light/12 h dark cycle and the same daily light integral (DLI). Both lighting strategies promoted plant growth but acted via different mechanisms. The multi-segment light intensity lighting strategy promoted plant growth by decreasing non-photochemical quenching (NPQ) of the excited state of chlorophyll and increasing the quantum yield of PSII electron transport (PhiPSII), quantum yield of the carboxylation rate (PhiCO2), and photochemical quenching (qP), also taking advantage of the circadian rhythm. The extended photoperiod lighting strategy promoted plant growth by compensating for weak light stress and increasing light-use efficiency by increasing chlorophyll content under weak light conditions.

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