In diatoms, a transthylakoid proton gradient alone is not sufficient to induce a non‐photochemical fluorescence quenching

Lavaud, Johann; Rousseau, Bernard; Étienne, Anne-Lise

doi:10.1016/s0014-5793(02)02979-4

Cited by 101 publications

(125 citation statements)

References 28 publications

(43 reference statements)

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“…Indeed, a sigmoidal relationship was found between the two parameters only in P. tricornutum [40]. The sigmoidal shape of the qNi component is not a peculiarity of P. tricornutum but has been found in each diatom species tested so far (see electronic supplementary material, Data S5).…”

Section: Resultsmentioning

confidence: 72%

Relaxation of the non-photochemical chlorophyll fluorescence quenching in diatoms: kinetics, components and mechanisms

Roháček

Bertrand

Moreau

et al. 2014

Phil. Trans. R. Soc. B

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Diatoms are especially important microorganisms because they constitute the larger group of microalgae. To survive the constant variations of the light environment, diatoms have developed mechanisms aiming at the dissipation of excess energy, such as the xanthophyll cycle and the non-photochemical chlorophyll (Chl) fluorescence quenching. This contribution is dedicated to the relaxation of the latter process when the adverse conditions cease. An original nonlinear regression analysis of the relaxation of non-photochemical Chl fluorescence quenching, qN, in diatoms is presented. It was used to obtain experimental evidence for the existence of three time-resolved components in the diatom Phaeodactylum tricornutum : qNf, qNi and qNs. qNf (s time-scale) and qNs (h time-scale) are exponential in shape. By contrast, qNi (min time-scale) is of sigmoidal nature and is dominant among the three components. The application of metabolic inhibitors (dithiothreitol, ammonium chloride, cadmium and diphenyleneiodonium chloride) allowed the identification of the mechanisms on which each component mostly relies. qNi is linked to the relaxation of the ΔpH gradient and the reversal of the xanthophyll cycle. qNs quantifies the stage of photoinhibition caused by the high light exposure, qNf seems to reflect fast conformational changes within thylakoid membranes in the vicinity of the photosystem II complexes.

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Section: Resultsmentioning

confidence: 72%

Relaxation of the non-photochemical chlorophyll fluorescence quenching in diatoms: kinetics, components and mechanisms

Roháček

Bertrand

Moreau

et al. 2014

Phil. Trans. R. Soc. B

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“…DTT (BDH-Prolabo) was prepared fresh as in Lavaud et al (2002a). A stock solution of 300 mM (in ethanol) was diluted in filtered seawater to prepare working solutions of concentrations ranging from 3.3 to 15 mM.…”

Section: Inhibitor Preparation and Effective Dosagementioning

confidence: 99%

“…To inhibit the activity of the xanthophyll cycle, the inhibitor of the diadinoxanthin de-epoxidase (DDE) dithiothreitol (DTT) was used. DTT is commonly used to inhibit the conversion of the pigment diadinoxanthin (DD) into the photoprotective form diatoxanthin (DT) (Lavaud et al 2002a). DTT was applied in combination with Lat A to ensure that the cells with the xanthophyll cycle inhibited remained exposed to high light.…”

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confidence: 99%

“…The degree of migration inhibition was estimated from the decrease in surface biomass following darkening, as estimated from the dark-adapted fluorescence level, F 0 . Three replicate samples were tested for each Lat A concentration.DTT (BDH-Prolabo) was prepared fresh as in Lavaud et al (2002a). A stock solution of 300 mM (in ethanol) was diluted in filtered seawater to prepare working solutions of concentrations ranging from 3.3 to 15 mM.…”

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confidence: 99%

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Efficiency of photoprotection in microphytobenthos: role of vertical migration and the xanthophyll cycle against photoinhibition

Serôdio¹,

Ezequiel²,

Barnett³

et al. 2012

Aquat. Microb. Ecol.

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The capacity of microphytobenthos to withstand the variable and extreme conditions of the intertidal environment, prone to cause photoinhibition, has been attributed to particularly efficient photoprotection. However, little is known regarding the capacity of this protection against photoinhibition or the mechanisms responsible for it. The present study quantified the photoprotective capacity and the extent of photoinhibition under excess light, estimated the contribution of vertical migration and the xanthophyll cycle to overall photoprotection, and evaluated the effects of photoacclimation. A new experimental protocol combined (1) chlorophyll fluorescence imaging, for the simultaneous measurement of replicates and experimental treatments, (2) specific inhibitors for vertical migration and for the xanthophyll cycle, to quantify the relative contribution of each process, and (3) recovery kinetics analysis of photosynthetic activity during light stress-recovery experiments, to distinguish rapidly reversible photochemical down-regulation from photoinhibition. The results show a high photoprotective capacity in 2 study periods, May and October, with photoinhibition rates below 20%. A clear change in photoacclimation state was observed, with acclimation to lower irradiances in autumn associated with higher susceptibility to photoinhibition. In May, vertical migration and the xanthophyll cycle provided comparable protection against photoinhibition; in October, the former predominated. The sum of their contributions was ~20% in both months, suggesting that other processes also contribute to photoprotection.KEY WORDS: Microphytobenthos · Photoinhibition · Photoprotection · Xanthophyll cycle · Vertical migration · Non-photochemical quenching · Chlorophyll fluorescence · Diatoms Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 67: [161][162][163][164][165][166][167][168][169][170][171][172][173][174][175] 2012 damaging to the photo synthetic apparatus when acting individually, the combined effects of all of these factors likely coalesce in the photoinhibition of photosynthesis of benthic microalgae. Of particular importance is the exposure to direct sunlight, which can result in excessive reductant pressure and in the formation of intracellular reactive oxygen species (ROS; Roncarati et al. 2008, Waring et al. 2010. High levels of ROS cause the permanent inactivation of photosystem II (PSII) protein D1, negatively im pacting photosynthetic yield and primary productivity (Nishiyama et al. 2006).Despite these harsh conditions, microphytobenthos of intertidal flats typically exhibit high growth rates, forming dense and diverse sedimentary biofilms, and are recognized as a major contributor to ecosystemlevel carbon fixation and primary productivity (Underwood & Kromkamp 1999). Furthermore, an apparent lack of photoinhibition in microphytobenthic biofilms has been repeatedly reported (Blanchard & Cariou-LeGall 1994, Kromkamp et al. 1998, Underwood 2002, Blanchard et ...

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“…Diatoms can dissipate excess light energy through distinct mechanisms of nonphotochemical quenching (NPQ) to limit overexcitation of their photosystems (Lavaud et al, 2002a(Lavaud et al, , 2002b(Lavaud et al, , 2004Eisenstadt et al, 2008;Grouneva et al, 2008Grouneva et al, , 2009Bailleul et al, 2010;Zhu and Green, 2010;Depauw et al, 2012;Lepetit et al, 2012). Some NPQ mechanisms are associated with the operation of a xanthophyll cycle, which converts epoxidized to deepoxidized forms of certain xanthophylls.…”

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confidence: 99%

Photosystem II Photoinactivation, Repair, and Protection in Marine Centric Diatoms

Roy

Alami

et al. 2012

Plant Physiology

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; Institut des sciences de la mer de Rimouski, Université du Québec, Rimouski, Quebec, Canada G5L 3A1 (S.R.); and Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (M.A., B.R.G.)Diatoms are important contributors to aquatic primary production, and can dominate phytoplankton communities under variable light regimes. We grew two marine diatoms, the small Thalassiosira pseudonana and the large Coscinodiscus radiatus, across a range of temperatures and treated them with a light challenge to understand their exploitation of variable light environments. In the smaller T. pseudonana, photosystem II (PSII) photoinactivation outran the clearance of PSII protein subunits, particularly in cells grown at sub-or supraoptimal temperatures. In turn the absorption cross section serving PSII photochemistry was down-regulated in T. pseudonana through induction of a sustained phase of nonphotochemical quenching that relaxed only slowly over 30 min of subsequent low-light incubation. In contrast, in the larger diatom C. radiatus, PSII subunit turnover was sufficient to counteract a lower intrinsic susceptibility to photoinactivation, and C. radiatus thus did not need to induce sustained nonphotochemical quenching under the high-light treatment. T. pseudonana thus incurs an opportunity cost of sustained photosynthetic down-regulation after the end of an upward light shift, whereas the larger C. radiatus can maintain a balanced PSII repair cycle under comparable conditions.

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In diatoms, a transthylakoid proton gradient alone is not sufficient to induce a non‐photochemical fluorescence quenching

Cited by 101 publications

References 28 publications

Relaxation of the non-photochemical chlorophyll fluorescence quenching in diatoms: kinetics, components and mechanisms

Relaxation of the non-photochemical chlorophyll fluorescence quenching in diatoms: kinetics, components and mechanisms

Efficiency of photoprotection in microphytobenthos: role of vertical migration and the xanthophyll cycle against photoinhibition

Photosystem II Photoinactivation, Repair, and Protection in Marine Centric Diatoms

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