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Peter Horton - One of the best experts on this subject based on the ideXlab platform.
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The Lhcb protein and xanthophyll composition of the light harvesting antenna controls the ΔpH-dependency of Non-Photochemical Quenching in Arabidopsis thaliana
FEBS Letters, 2008Co-Authors: María L. Pérez-bueno, Matthew P. Johnson, Alexander V Ruban, Ahmad Zia, Peter HortonAbstract:Nonphotochemical Quenching (NPQ) is the photoprotective dissipation of energy in photosynthetic membranes. The hypothesis that the ΔpH-dependent component of NPQ (qE) component of Non-Photochemical Quenching is controlled allosterically by the xanthophyll cycle has been tested using Arabidopsis mutants with different xanthophyll content and composition of Lhcb proteins. The titration curves of qE against ΔpH were different in chloroplasts containing zeaxanthin or violaxanthin, proving their roles as allosteric activator and inhibitor, respectively. The curves differed in mutants deficient in lutein and specific Lhcb proteins. The results show that qE is determined by xanthophyll occupancy and the structural interactions within the antenna that govern allostericity.
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the xanthophyll cycle pool size controls the kinetics of non photochemical Quenching in arabidopsis thaliana
FEBS Letters, 2008Co-Authors: Matthew P. Johnson, Paul A Davison, Alexander V Ruban, Peter HortonAbstract:Arabidopsis plants overexpressing β-carotene hydroxylase 1 accumulate over double the amount of zeaxanthin present in wild-type plants. The final amplitude of Non-Photochemical Quenching (NPQ) was found to be the same in these plants, but the kinetics were different. The formation and relaxation of NPQ consistently correlated with the de-epoxidation state of the xanthophyll cycle pool and not the amount of zeaxanthin. These data indicate that zeaxanthin and violaxanthin antagonistically regulate the switch between the light harvesting and photoprotective modes of the light harvesting system and show that control of the xanthophyll cycle pool size is necessary to optimize the kinetics of NPQ.
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Control of the light harvesting function of chloroplast membranes: The LHCII‐aggregation model for non‐photochemical Quenching
FEBS Letters, 2005Co-Authors: Peter Horton, Mark Wentworth, Alexander V RubanAbstract:Dissipation of excess excitation energy within the photosystem II light-harvesting antenna (LHCII) by Non-Photochemical Quenching (NPQ) is an important photoprotective process in plants. An update to a hypothesis for the mechanism of NPQ [FEBS Letters 292, 1991] is presented. The impact of recent advances in understanding the structure, organisation and photophysics of LHCII is assessed. We show possible locations of the predicted regulatory and Quenching pigment-binding sites in the structural model of the major LHCII. We suggest that NPQ is a highly regulated concerted response of the organised thylakoid macrostructure, which can include different mechanisms and sites at different times.
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Regulation of Non-Photochemical Quenching of Chlorophyll Fluorescence in Plants
Functional Plant Biology, 1995Co-Authors: Alexander V Ruban, Peter HortonAbstract:Non-Photochemical Quenching of chlorophyll fluorescence indicates the de-excitation of light-generated excited states in the chlorophyll associated with photosystem II (PSII). The principle process contributing to this Quenching is dependent on the formation of the thylakoid proton gradient and is an important mechanism for protecting PSII from photodamage. Evidence points to the importance of the light-harvesting chlorophyll proteins as the site of dissipation of energy, and suggests that the structure and function of these proteins are regulated by protonation and the ratio of zeaxanthin to violaxanthin. The minor light-harvesting proteins may have a particularly important role as the primary sites of proton binding and because of their enrichment in xanthophyll cycle carotenoids. The dynamic nature of the light-harvesting system is an important part of the process by which plants are able to adapt to different light environments.
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Activation of Non-Photochemical Quenching in thylakoids and leaves
Planta, 1994Co-Authors: Giles N. Johnson, Andrew J. Young, Peter HortonAbstract:The mechanism of rapidly-relaxing Non-Photochemical Quenching in two plant species,Chenopodium album L. andDigitalis purpurea L., that differ considerably in their capacity for such Quenching has been investigated (Johnson G.N. et al. 1993, Plant Cell Environ. 16, 673–679). Illumination of leaves of both species in the presence of 2% O2 balance N2 led to the formation of zeaxanthin. When thylakoids were isolated from leaves of each species that had been so treated it was found that in D. purpurea Non-Photochemical Quenching was “activated” relative to the control; a higher level of Quenching was found for a given trans-thylakoid pH gradient. No such activation of Non-Photochemical Quenching was observed in C. album. Similar conclusions were drawn when comparing Quenching in intact leaves. It is concluded that light activation of Quenching is a process that cannot readily be induced in C. album. Measurement of the sensitivity of Non-Photochemical Quenching in leaves of C. album andD. purpurea to dithiothreitol (DTT; a reagent that inhibits formation of zeaxanthin) showed differences between the two species. In both cases, feeding leaves with DTT inhibited the light-induced formation of zeaxanthin. InC. album this was accompanied by complete inhibition of reversible Non-Photochemical Quenching, whereas in D. purpurea this inhibition was only partial. Data are discussed in relation to studies on the mechanism of Quenching and the role of zeaxanthin in this process.
Peter Jahns - One of the best experts on this subject based on the ideXlab platform.
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A mathematical model of Non-Photochemical Quenching to study short-term light memory in plants
Biochimica et Biophysica Acta, 2016Co-Authors: Anna Matuszyńska, Somayyeh Heidari, Peter Jahns, Oliver EbenhöhAbstract:Abstract Plants are permanently exposed to rapidly changing environments, therefore it is evident that they had to evolve mechanisms enabling them to dynamically adapt to such fluctuations. Here we study how plants can be trained to enhance their photoprotection and elaborate on the concept of the short-term illumination memory in Arabidopsis thaliana . By monitoring fluorescence emission dynamics we systematically observe the extent of Non-Photochemical Quenching (NPQ) after previous light exposure to recognise and quantify the memory effect. We propose a simplified mathematical model of photosynthesis that includes the key components required for NPQ activation, which allows us to quantify the contribution to photoprotection by those components. Due to its reduced complexity, our model can be easily applied to study similar behavioural changes in other species, which we demonstrate by adapting it to the shadow-tolerant plant Epipremnum aureum . Our results indicate that a basic mechanism of short-term light memory is preserved. The slow component, accumulation of zeaxanthin, accounts for the amount of memory remaining after relaxation in darkness, while the fast one, antenna protonation, increases Quenching efficiency. With our combined theoretical and experimental approach we provide a unifying framework describing common principles of key photoprotective mechanisms across species in general, mathematical terms.
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A mathematical model of Non-Photochemical Quenching to study short-term light memory in plants
2016Co-Authors: Anna Matuszyńska, Somayyeh Heidari, Peter Jahns, Oliver EbenhoehAbstract:The concept of plant memory triggers a quite controversial dispute on the definition, extent or even existence of such. Because plants are permanently exposed to rapidly changing environments it is evident that they had to evolve mechanisms enabling them to dynamically adapt to such fluctuations. Recognizing memory as a timed response to changes of external inputs through amplification and integration of multiple signals, here we study the short-term illumination memory in Arabidopsis thaliana by monitoring fluorescence emission dynamics. For this, we designed an experiment to systematically determine the extent of Non-Photochemical Quenching (NPQ) after previous light exposure. We propose a simplified, mathematical model of photosynthesis that includes the key components required for NPQ activation. Due to its reduced complexity, our model is universally applicable to other species, which we demonstrate by adapting it to the shadow-tolerant plant Epipremnum aureum. We demonstrate that a basic mechanism of short-term light memory, which is based on two interacting components, can explain our experimental observations. The slow component, accumulation of zeaxanthin, accounts for the amount of memory remaining after relaxation in darkness, while the fast one, antennae protonation, increases Quenching efficiency. With this combined theoretical and experimental approach we provide a unifying framework that helps to uncover general principles of key photoprotective mechanisms across species.
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Non-Photochemical Quenching Mechanisms in Intact Organisms as Derived from Ultrafast-Fluorescence Kinetic Studies
Advances in Photosynthesis and Respiration, 2014Co-Authors: Alfred R. Holzwarth, Peter JahnsAbstract:Chlorophyll fluorescence kinetic studies provide strong evidence for the occurrence of at least two independent Quenching sites, giving rise to Non-Photochemical Quenching of fluorescence, in plants. We discuss a “4-state 2-site Quenching model” that integrates the data from those fluorescence studies as well as a large body of additional, previously contradicting, information in a consistent manner. In vitro models of the two Quenching sites, named Q1 (PsbS-dependent; located in detached antenna complexes) and Q2 (zeaxanthin dependent, located in antenna proteins that remain attached to the reaction center), are also discussed, along with currently available evidence for the different Quenching mechanisms in these sites. At the end of the chapter, we discuss the exceptional potential of ultrafast time-resolved fluorescence to characterize in vivo Quenching situations in detail and to distinguish between a range of possible theoretical Quenching models and sites.
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On the relationship between Non-Photochemical Quenching and photoprotection of Photosystem II
Biochimica et Biophysica Acta, 2012Co-Authors: Petar H. Lambrev, Peter Jahns, Yuliya Miloslavina, Alfred R. HolzwarthAbstract:Abstract Non-Photochemical Quenching (NPQ) of chlorophyll fluorescence is thought to be an indicator of an essential regulation and photoprotection mechanism against high-light stress in photosynthetic organisms. NPQ is typically characterized by modulated pulse fluorometry and it is often assumed implicitly to be a good proxy for the actual physiological photoprotection capacity of the organism. Using the results of previously published ultrafast fluorescence measurements on intact leaves of w.t. and mutants of Arabidopsis (Holzwarth et al. 2009) we have developed exact relationships for the fluorescence Quenching and the corresponding Photosystem II acceptor side photoprotection effects under NPQ conditions. The approach based on the exciton–radical pair equilibrium model assumes that photodamage results from triplet states generated in the reaction center. The derived relationships allow one to distinguish and determine the individual and combined Quenching as well as photoprotection contributions of each of the multiple NPQ mechanisms. Our analysis shows inter alia that Quenching and photoprotection are not linearly related and that antenna detachment, which can be identified with the so-called qE mechanism, contributes largely to the measured fluorescence Quenching but does not correspond to the most efficient photoprotective response. Conditions are formulated which allow simultaneously the maximal photosynthetic electron flow as well as maximal acceptor side photoprotection. It is shown that maximal photoprotection can be achieved if NPQ is regulated in such a way that PSII reaction centers are open under given light conditions. The results are of fundamental importance for a proper interpretation of the physiological relevance of fluorescence-based NPQ data.
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identification of a slowly inducible zeaxanthin dependent component of non photochemical Quenching of chlorophyll fluorescence generated under steady state conditions in arabidopsis
Biochimica et Biophysica Acta, 2010Co-Authors: Manuela Nilkens, Yuliya Miloslavina, Petar H. Lambrev, Alfred R. Holzwarth, Eugen Kress, Marc Muller, Peter JahnsAbstract:Abstract The induction and relaxation of Non-Photochemical Quenching (NPQ) under steady-state conditions, i.e. during up to 90 min of illumination at saturating light intensities, was studied in Arabidopsis thaliana . Besides the well-characterized fast qE and the very slow qI component of NPQ, the analysis of the NPQ dynamics identified a zeaxanthin (Zx) dependent component which we term qZ. The formation (rise time 10–15 min) and relaxation (lifetime 10–15 min) of qZ correlated with the synthesis and epoxidation of Zx, respectively. Comparative analysis of different NPQ mutants from Arabidopsis showed that qZ was clearly not related to qE, qT or qI and thus represents a separate, Zx-dependent NPQ component.
Radek Kaňa - One of the best experts on this subject based on the ideXlab platform.
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photoprotective strategies in the motile cryptophyte alga rhodomonas salina role of non photochemical Quenching ions photoinhibition and cell motility
Folia Microbiologica, 2019Co-Authors: Radek Kaňa, Barbora Šedivá, Eva Kotabova, Eliska TrskovaAbstract:We explored photoprotective strategies in a cryptophyte alga Rhodomonas salina. This cryptophytic alga represents phototrophs where chlorophyll a/c antennas in thylakoids are combined with additional light-harvesting system formed by phycobiliproteins in the chloroplast lumen. The fastest response to excessive irradiation is induction of Non-Photochemical Quenching (NPQ). The maximal NPQ appears already after 20 s of excessive irradiation. This initial phase of NPQ is sensitive to Ca2+ channel inhibitor (diltiazem) and disappears, also, in the presence of non-actin, an ionophore for monovalent cations. The prolonged exposure to high light of R. salina cells causes photoinhibition of photosystem II (PSII) that can be further enhanced when Ca2+ fluxes are inhibited by diltiazem. The light-induced reduction in PSII photochemical activity is smaller when compared with immotile diatom Phaeodactylum tricornutum. We explain this as a result of their different photoprotective strategies. Besides the protective role of NPQ, the motile R. salina also minimizes high light exposure by increased cell velocity by almost 25% percent (25% from 82 to 104 μm/s). We suggest that motility of algal cells might have a photoprotective role at high light because algal cell rotation around longitudinal axes changes continual irradiation to periodically fluctuating light.
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presence of flexible non photochemical Quenching in cryptophytes rhodomonas salina
2013Co-Authors: Radek Kaňa, Eva Kotabova, Ondřej PrasilAbstract:Photosynthesis uses light as a source of energy but its excess can result in damage of photosynthetic apparatus. The protective mechanism of Non-Photochemical Quenching (NPQ) can safely dissipate excess of light to heat. Presence and mechanism of NPQ regulation differs between photothrophs. Here we show presence of Non-Photochemical Quenching in cryptophyte alga (Rhodomonas salina), that represents unique clade of chromalveolates. Cryptophytes are exceptional among photosynthetic chromalveolates (that include also diatoms and other Chl c containing algae) because beside membrane-bound chlorophyll a/c proteins they also contain lumenal phycobiliproteins. We have shown that NPQ in R. salina is stimulated by light absorbed by chlorophyll (orange light — 620 nm) and phycoerythrin (green light — 520 nm) to the same extent with the same maximal value around 1.6. Kinetic pattern of NPQ stimulation in high light and its recovery in dark resemble flexible energetic Quenching, qE. It indicates different regulation of NPQ in cryptophytes in comparison to the same process known in diatoms because there recovery from Quenching state is usually less flexible.
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non photochemical Quenching in cryptophyte alga rhodomonas salina is located in chlorophyll a c antennae
PLOS ONE, 2012Co-Authors: Radek Kaňa, Eva Kotabova, Roman Sobotka, Ondřej PrasilAbstract:Photosynthesis uses light as a source of energy but its excess can result in production of harmful oxygen radicals. To avoid any resulting damage, phototrophic organisms can employ a process known as Non-Photochemical Quenching (NPQ), where excess light energy is safely dissipated as heat. The mechanism(s) of NPQ vary among different phototrophs. Here, we describe a new type of NPQ in the organism Rhodomonas salina, an alga belonging to the cryptophytes, part of the chromalveolate supergroup. Cryptophytes are exceptional among photosynthetic chromalveolates as they use both chlorophyll a/c proteins and phycobiliproteins for light harvesting. All our data demonstrates that NPQ in cryptophytes differs significantly from other chromalveolates – e.g. diatoms and it is also unique in comparison to NPQ in green algae and in higher plants: (1) there is no light induced xanthophyll cycle; (2) NPQ resembles the fast and flexible energetic Quenching (qE) of higher plants, including its fast recovery; (3) a direct antennae protonation is involved in NPQ, similar to that found in higher plants. Further, fluorescence spectroscopy and biochemical characterization of isolated photosynthetic complexes suggest that NPQ in R. salina occurs in the chlorophyll a/c antennae but not in phycobiliproteins. All these results demonstrate that NPQ in cryptophytes represents a novel class of effective and flexible Non-Photochemical Quenching.
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Thermoimaging as a tool for studying light-induced heating of leaves: Correlation of heat dissipation with the efficiency of photosystem II photochemistry and Non-Photochemical Quenching
Environmental and Experimental Botany, 2008Co-Authors: Radek Kaňa, Imre VassAbstract:Abstract Thermoimaging – a highly sensitive and non-invasive method of temperature measurement – was applied to explore the role of changing photosynthetic efficiency in light-induced heating of tobacco ( Nicotiana tabacum cv. Samsun ) leaves. In the absence of evaporative cooling through the stomata, which was achieved by covering leaves with Vaseline, illumination with 50–1400 μM photons m −2 s −1 intensity of photosynthetically active radiation resulted in ≈1–5 °C leaf temperature increase in about 2 min. The heating effect showed a non-linear correlation with the extent of Non-Photochemical Quenching (NPQ) resulting in higher leaf temperatures at higher NPQ values. When leaves were adapted to excessive irradiance (1300 μM photons m −2 s −1 for 6 h), which resulted in reduction of photosynthetic efficiency and amplification of NPQ the light-induced heating effect was enhanced. The experimental results have been explained on the basis of a simple theoretical model characterizing the balance of energy fluxes in leaves in relation to the efficiency of photosystem II photochemistry and Non-Photochemical Quenching. The role of alternative energy dissipation pathways outside of PSII in the phenomenon of light-induced leaf heating is also discussed.
Alfred R. Holzwarth - One of the best experts on this subject based on the ideXlab platform.
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Thylakoid membrane reorganizations revealed by small-angle neutron scattering of Monstera deliciosa leaves associated with Non-Photochemical Quenching
Open Biology, 2020Co-Authors: Renáta Ünnep, Alfred R. Holzwarth, Suman Paul, Ottó Zsiros, László Kovács, Noemi Szekely, Gábor Steinbach, Marie-sousai Appavou, Lionel Porcar, Győző GarabAbstract:Non-Photochemical Quenching (NPQ) is an important photoprotective mechanism in plants and algae. Although the process is extensively studied, little is known about its relationship with ultrastruct...
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Non-Photochemical Quenching Mechanisms in Intact Organisms as Derived from Ultrafast-Fluorescence Kinetic Studies
Advances in Photosynthesis and Respiration, 2014Co-Authors: Alfred R. Holzwarth, Peter JahnsAbstract:Chlorophyll fluorescence kinetic studies provide strong evidence for the occurrence of at least two independent Quenching sites, giving rise to Non-Photochemical Quenching of fluorescence, in plants. We discuss a “4-state 2-site Quenching model” that integrates the data from those fluorescence studies as well as a large body of additional, previously contradicting, information in a consistent manner. In vitro models of the two Quenching sites, named Q1 (PsbS-dependent; located in detached antenna complexes) and Q2 (zeaxanthin dependent, located in antenna proteins that remain attached to the reaction center), are also discussed, along with currently available evidence for the different Quenching mechanisms in these sites. At the end of the chapter, we discuss the exceptional potential of ultrafast time-resolved fluorescence to characterize in vivo Quenching situations in detail and to distinguish between a range of possible theoretical Quenching models and sites.
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On the relationship between Non-Photochemical Quenching and photoprotection of Photosystem II
Biochimica et Biophysica Acta, 2012Co-Authors: Petar H. Lambrev, Peter Jahns, Yuliya Miloslavina, Alfred R. HolzwarthAbstract:Abstract Non-Photochemical Quenching (NPQ) of chlorophyll fluorescence is thought to be an indicator of an essential regulation and photoprotection mechanism against high-light stress in photosynthetic organisms. NPQ is typically characterized by modulated pulse fluorometry and it is often assumed implicitly to be a good proxy for the actual physiological photoprotection capacity of the organism. Using the results of previously published ultrafast fluorescence measurements on intact leaves of w.t. and mutants of Arabidopsis (Holzwarth et al. 2009) we have developed exact relationships for the fluorescence Quenching and the corresponding Photosystem II acceptor side photoprotection effects under NPQ conditions. The approach based on the exciton–radical pair equilibrium model assumes that photodamage results from triplet states generated in the reaction center. The derived relationships allow one to distinguish and determine the individual and combined Quenching as well as photoprotection contributions of each of the multiple NPQ mechanisms. Our analysis shows inter alia that Quenching and photoprotection are not linearly related and that antenna detachment, which can be identified with the so-called qE mechanism, contributes largely to the measured fluorescence Quenching but does not correspond to the most efficient photoprotective response. Conditions are formulated which allow simultaneously the maximal photosynthetic electron flow as well as maximal acceptor side photoprotection. It is shown that maximal photoprotection can be achieved if NPQ is regulated in such a way that PSII reaction centers are open under given light conditions. The results are of fundamental importance for a proper interpretation of the physiological relevance of fluorescence-based NPQ data.
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identification of a slowly inducible zeaxanthin dependent component of non photochemical Quenching of chlorophyll fluorescence generated under steady state conditions in arabidopsis
Biochimica et Biophysica Acta, 2010Co-Authors: Manuela Nilkens, Yuliya Miloslavina, Petar H. Lambrev, Alfred R. Holzwarth, Eugen Kress, Marc Muller, Peter JahnsAbstract:Abstract The induction and relaxation of Non-Photochemical Quenching (NPQ) under steady-state conditions, i.e. during up to 90 min of illumination at saturating light intensities, was studied in Arabidopsis thaliana . Besides the well-characterized fast qE and the very slow qI component of NPQ, the analysis of the NPQ dynamics identified a zeaxanthin (Zx) dependent component which we term qZ. The formation (rise time 10–15 min) and relaxation (lifetime 10–15 min) of qZ correlated with the synthesis and epoxidation of Zx, respectively. Comparative analysis of different NPQ mutants from Arabidopsis showed that qZ was clearly not related to qE, qT or qI and thus represents a separate, Zx-dependent NPQ component.
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Ultrafast fluorescence study on the location and mechanism of Non-Photochemical Quenching in diatoms.
Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2009Co-Authors: Yuliya Miloslavina, Petar H. Lambrev, Irina Grouneva, Bernard Lepetit, Reimund Goss, Christian Wilhelm, Alfred R. HolzwarthAbstract:The diatom algae, responsible for at least a quarter of the global photosynthetic carbon assimilation in the oceans, are capable of switching on rapid and efficient photoprotection, which helps them cope with the large fluctuations of light intensity in the moving waters. The enhanced dissipation of excess excitation energy becomes visible as Non-Photochemical Quenching (NPQ) of chlorophyll a fluorescence. Intact cells of the diatoms Cyclotella meneghiniana and Phaeodactylum tricornutum, which show different NPQ induction kinetics under high light illumination, were investigated by picosecond time-resolved fluorescence under dark and NPQ-inducing high light conditions. The fluorescence kinetics revealed that there are two independent sites responsible for NPQ. The first Quenching site is located in an FCP antenna system that is functionally detached from both photosystems, while the second Quenching site is located in the PSII-attached antenna. Notwithstanding their different npq induction and reversal kinetics, both diatoms showed identical NPQ via both mechanisms in the steady-state. Their fluorescence decays in the dark-adapted states were different, however. A detailed Quenching model is proposed for NPQ in diatoms.
Ondřej Prasil - One of the best experts on this subject based on the ideXlab platform.
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presence of flexible non photochemical Quenching in cryptophytes rhodomonas salina
2013Co-Authors: Radek Kaňa, Eva Kotabova, Ondřej PrasilAbstract:Photosynthesis uses light as a source of energy but its excess can result in damage of photosynthetic apparatus. The protective mechanism of Non-Photochemical Quenching (NPQ) can safely dissipate excess of light to heat. Presence and mechanism of NPQ regulation differs between photothrophs. Here we show presence of Non-Photochemical Quenching in cryptophyte alga (Rhodomonas salina), that represents unique clade of chromalveolates. Cryptophytes are exceptional among photosynthetic chromalveolates (that include also diatoms and other Chl c containing algae) because beside membrane-bound chlorophyll a/c proteins they also contain lumenal phycobiliproteins. We have shown that NPQ in R. salina is stimulated by light absorbed by chlorophyll (orange light — 620 nm) and phycoerythrin (green light — 520 nm) to the same extent with the same maximal value around 1.6. Kinetic pattern of NPQ stimulation in high light and its recovery in dark resemble flexible energetic Quenching, qE. It indicates different regulation of NPQ in cryptophytes in comparison to the same process known in diatoms because there recovery from Quenching state is usually less flexible.
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non photochemical Quenching in cryptophyte alga rhodomonas salina is located in chlorophyll a c antennae
PLOS ONE, 2012Co-Authors: Radek Kaňa, Eva Kotabova, Roman Sobotka, Ondřej PrasilAbstract:Photosynthesis uses light as a source of energy but its excess can result in production of harmful oxygen radicals. To avoid any resulting damage, phototrophic organisms can employ a process known as Non-Photochemical Quenching (NPQ), where excess light energy is safely dissipated as heat. The mechanism(s) of NPQ vary among different phototrophs. Here, we describe a new type of NPQ in the organism Rhodomonas salina, an alga belonging to the cryptophytes, part of the chromalveolate supergroup. Cryptophytes are exceptional among photosynthetic chromalveolates as they use both chlorophyll a/c proteins and phycobiliproteins for light harvesting. All our data demonstrates that NPQ in cryptophytes differs significantly from other chromalveolates – e.g. diatoms and it is also unique in comparison to NPQ in green algae and in higher plants: (1) there is no light induced xanthophyll cycle; (2) NPQ resembles the fast and flexible energetic Quenching (qE) of higher plants, including its fast recovery; (3) a direct antennae protonation is involved in NPQ, similar to that found in higher plants. Further, fluorescence spectroscopy and biochemical characterization of isolated photosynthetic complexes suggest that NPQ in R. salina occurs in the chlorophyll a/c antennae but not in phycobiliproteins. All these results demonstrate that NPQ in cryptophytes represents a novel class of effective and flexible Non-Photochemical Quenching.