This work was supported by National Science Foundation Grant IBN 950-6254 (to A.R.G. Measurements of Chl fluorescence lifetime distributions in isolated thylakoids have distinguished two distinct components that contribute to a ΔpH-dependent decrease in the fluorescence yield (32, 54). The development of NPQ correlates with the synthesis of zeaxanthin (Z) and antheraxanthin (A) from violaxanthin (V) via the xanthophyll cycle, which is depicted in Fig. These conditions activate the conversion of V to Z; the latter is a more effective acceptor of excitation energy from 1Chl, thereby allowing dynamic increases in the extent of photoprotection in excessive light. Biophys. The npq1 mutant is defective in the xanthophyll cycle and could not convert V to A and Z on exposure to excessive light (Figs. We analyzed the response of potted strawberry tree (Arbutus unedo L.) seedlings exposed to water stress by withholding water for 10 d (WS). Plant Physiol. 2 and Table 2). In the present review, we summarize current knowledge about the violaxanthin cycle of vascular plants, green and brown algae, and the diadinoxanthin cycle of the algal classes Bacillariophyceae, Xanthophyceae, Haptophyceae, and Dinophyceae. 64" has been identified as a process with a significant impact on the reflectance at around 525 nm. We do not capture any email address. Xanthophyll pigments have critical structural and functional roles in the photosynthetic light-harvesting complexes of algae and vascular plants. Posted … Basic. Based on the substoichiometric levels of β-carotene-derived xanthophylls per LHC monomer, it was suggested that these xanthophylls bind to sites on the LHC distinct from those to which lutein binds (19, 49). We analyzed the response of potted strawberry tree (Arbutus unedo L.) seedlings exposed to water stress by withholding water for 10 d (WS). eCollection 2020. da Rocha Nina Junior A, Furtunato Maia JM, Vitor Martins SC, Gonçalves JFC. Because the lowest singlet energy state of lutein is likely to be higher than that of Z (and therefore closer to the lowest energy state of 1Chl), lutein may be a weaker quencher at pH values not saturating for NPQ. When Z and A are present, a new low pH-dependent fluorescence lifetime component of 0.4 ns appears at the expense of the 1.6-ns component. Violaxanthin de-epoxidase (VDE) is the key enzyme responsible for zeaxanthin synthesis from violaxanthin under … Li Z, Juneau P, Lian Y, Zhang W, Wang S, Wang C, Shu L, Yan Q, He Z, Xu K. Plants (Basel). The xanthophyll cycle, in which the carotenoid pigment violaxanthin is reversibly converted into zeaxanthin, is ubiquitous among green algae and plants and is necessary for the regulation of light harvesting, protection from oxidative stress and adaptation to different light … COVID-19 is an emerging, rapidly evolving situation. K.K.N. 69-76. His productions aim to promote science as a visual and emotional experience. -, Arch Biochem Biophys. Hence, lutein, loroxanthin, or both must contribute to the de-excitation of 1Chl. … was also supported by a fellowship from the Department of Energy/National Science Foundation/U.S. To elucidate the roles of specific xanthophylls in photoprotection, we used a video imaging system to isolate mutants of the unicellular green alga Chlamydomonas reinhardtii that were impaired in NPQ and xanthophyll metabolism (22). Demmig-Adams B, Stewart JJ, López-Pozo M, Polutchko SK, Adams WW 3rd. Some carotenoids play an important role in preventing photo-oxidative damage to the photosynthetic apparatus or to the intracellular materials of plants under high- irradiance conditions ( Raw, 1988 ; Young and Britton, 1990 ). Specific xanthophylls are involved in the de-excitation of singlet Chl (1Chl) that accumulates in the LHC under conditions of excessive illumination (10–14). CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): There is widespread agreement that the xanthophyll cycle provides a major photoprotection system for photosynthesis in green leaves (l-8). Carotenoid biosynthetic pathway in C. reinhardtii. 1 Departamento de Biologia and CESAM (Centro de Estudos do Ambiente e do Mar), Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, … Image credit: Shutterstock/greenbutterfly. 2020 Dec 10;25(24):5825. doi: 10.3390/molecules25245825. NIH Others have noted xanthophyll cycle-independent NPQ under conditions likely to generate a high lumenal [H+], such as during the illumination of leaves in an atmosphere of 1% O2 and 0% CO2 (52). The results may indicate that photoprotection by xanthophyll pigments assists the development of phytoplankton blooms under high-irradiance conditions. The role of the xanthophyll cycle in regulating the energy flow to the PS II reaction centers and therefore in photoprotection was studied by measurements of light-induced absorbance changes, Chl fluorescence, and photosynthetic O2 evolution in sun and shade leaves of Hedera canariensis. The role of zeaxanthin is still unclear in green algae, and a peculiar violaxanthin de‐epoxidating enzyme was found in the model organism Chlamydomonas reinhardtii . Enhanced Photoprotection by Protein-Bound vs Free Xanthophyll Pools: A Comparative Analysis of Chlorophyll b and Xanthophyll Biosynthesis Mutants Luca Dall’Ostoa, Stefano Cazzanigaa, Michel Havauxb,c,d and Roberto Bassia,1 a Dipartimento di Biotecnologie, Universita` di Verona, Strada Le Grazie 15, 37134, Verona, Italy b CEA, IBEB, SBVME, Laboratoire d’Ecophysiologie Mole´culaire des Plantes, … The role of the xanthophyll cycle in the photoprotection of PSII with respect to qE [84]. Keep search filters New search. Online ISSN 1091-6490. 21’. and O.B.). A xanthophyll cycle pigment-independent shift in the fluorescence lifetime from 2.0 to 1.6 ns occurs on acidification of isolated thylakoid membranes. Spinach, kale, kiwi, green apples, egg yolk, corn etc. Dithiothreitol, an inhibitor of violaxanthin de-epoxidation, increases the susceptibility of leaves ofNerium oleander L. to photoinhibition of photosynthesis. 1, pp. Thus the xanthophyll cycle, which consists in the conversion (de-epoxidation) of violaxanthin (V) to Z via A under excess irradiance and in the reversed reaction (epoxidation) under low irradiance, plays a central role in photoprotection (Demmig-Adams and Adams 1992, 1996b, Pfündel and Bilger 1994). Violaxanthin Cycle . 2020 Dec 10;9(12):1748. doi: 10.3390/plants9121748. Values are the means of two independent experiments. The predominant carotenoids associated with the LHCs of this strain are likely to be V and neoxanthin, because these two xanthophylls, but not β-carotene, can substitute for lutein in LHC reconstitution assays (46). The npq1 and lor1 single mutants grew relatively normally in high light (Fig. Enter multiple addresses on separate lines or separate them with commas. This question is for testing whether or not you are a human visitor and to prevent automated spam submissions. Alternatively, unique structural features of Z, A, and lutein may be required for protonation-induced conformation changes of specific inner LHC proteins to which these xanthophylls are bound; these changes could result in de-excitation of 1Chl that does not involve direct transfer of excitation energy from Chl to xanthophyll (14, 45). Effects of Titanium Dioxide Nanoparticles on Photosynthetic and Antioxidative Processes of. 1990 Feb;92(2):293-301 The project will focus on the roll of the xanthophyll cycle in photoprotection. … The Fv/Fm ratio, measured in darkness showed a much greater decrease in the presence than in the absence of DTT. The Australian National Univ., Research School of Biological Sciences, Photobioenergetics Group, GPO Box 475, Canberra. SUN*, and X.L. Differential dependence of apple (Malus domestica Borkh.) 3). 1Chl can also enter the triplet state (3Chl) by intersystem crossing, and 3Chl can facilitate the formation of the highly toxic singlet oxygen molecule (1O2). 2 and Table 2) that accumulate as intermediates in the synthesis of V (Fig. Dlouhý O, Kurasová I, Karlický V, Javornik U, Šket P, Petrova NZ, Krumova SB, Plavec J, Ughy B, Špunda V, Garab G. Sci Rep. 2020 Jul 20;10(1):11959. doi: 10.1038/s41598-020-68854-x. The role of the xanthophyll cycle in regulating the energy flow to the PS II reaction centers and therefore in photoprotection was studied by measurements of light-induced absorbance changes, Chl fluorescence, and photosynthetic O2 evolution in sun and shade leaves of Hedera canariensis. Reimund Goss, Torsten Jakob, Regulation and function of xanthophyll cycle-dependent photoprotection in algae, Photosynthesis Research, 10.1007/s11120-010-9536-x, 106, 1-2, (103-122), (2010). Planta. A major function of the cycle is to protect the photosynthetic system from the potentially damaging effects of high light by dissipating excess energy that might otherwise damage the photosynthetic apparatus harmlessly as heat by a process termed non-photochemical quenching (NFQ). The latter species could cause irreversible photo-oxidative damage unless it were de-excited by interactions with carotenoids or scavenged by antioxidants such as α-tocopherol. Advanced search The results presented here have enabled us to develop a model for NPQ that incorporates functions for both the α- and β-carotene-derived xanthophylls. Cells were streaked on minimal agar medium, incubated overnight at 50 μmol photons m−2⋅s−1, and grown photoautotrophically for 6 days at the indicated PFD. 3). 1 and 2), had reduced NPQ (Fig. Cells were grown at an incident PFD of 70 μmol photons m−2⋅s−1 and dark-adapted overnight. Direct interaction between Chl and xanthophylls is consistent with the results of our genetic analysis, which revealed roles for Z, A, and lutein in the de-excitation of 1Chl in vivo. This review focuses on the ubiquity of photoprotection associated with a group of interconvertible leaf carotenoids, the xanthophyll cycle. Carotenoids are known for versatile roles they play in living organisms; however, their most pivotal function is involvement in scavenging reactive oxygen species (ROS) and photoprotection. Modulation of non-bilayer lipid phases and the structure and functions of thylakoid membranes: effects on the water-soluble enzyme violaxanthin de-epoxidase. USA.gov. Mechanistic aspects of xanthophyll cycle‐dependent photoprotection in higher plant chloroplasts and leaves. The xanthophyll cycle represents one of the important photoprotection mechanisms in plant cells. Furthermore, the energies of the lowest singlet and triplet excited states decrease with increasing conjugation length. Because V is de-epoxidated efficiently in the lor1 mutant (Fig. -. Estimates of excited state energy levels suggest that the lowest singlet state (21Ag or S1) of Z and A can accept excitation energy directly from 1Chl (15–17); the excited xanthophylls return to ground state by nonradiative heat dissipation. Rapid adjustments are required to maintain fitness because of a trade-off between efficient solar energy conversion and photoprotection. In contrast, a double mutant that was defective in the synthesis of lutein, loroxanthin (α-carotene branch), zeaxanthin, and antheraxanthin (β-carotene branch) had almost no nonphotochemical quenching and was extremely sensitive to high light. This double mutant was unable to synthesize α-carotene, lutein, and loroxanthin or to convert V to A and Z (Figs. (Eds B Demmig-Adams, WW Adams III, AK Mattoo) pp. University Park (State College), PA.: 288-297. The finding that lutein plays an important role in NPQ emphasizes how the generation and characterization of mutants can be used to dissect photoprotection in plants. 66" engagement of xanthophyll cycle pigments to photoprotection, emerges at the wavelengths These latter conditions were used in many experiments that led to the conclusion that essentially all NPQ was dependent on Z and A (53–55). Department of Agriculture Training Program in Plant Biology at Stanford University. In addition, duplicate samples were analyzed on a Microsorb-MV (Rainin, Woburn, MA) column (28) to determine the proportion of neoxanthin and loroxanthin, which cochromatographed on the ODS-1 column. ↵* To whom reprint requests should be addressed. Diversity and adaptation in oak species; Proceedings of the second meeting of working party 2.08.05, genetics of Quercus, of the International Union of Forest Research Organizations; 1997 October 12-17;. Zeaxanthin, a Molecule for Photoprotection in Many Different Environments. Photoprotection of photosystem II (PSII) is essential to avoid the light-induced damage of the photosynthetic apparatus due to the formation of reactive oxygen species (=photo-oxidative stress) under excess light. 530 and … The analysis of mutants so far has demonstrated that almost all rapidly reversible NPQ depends on specific xanthophylls derived from both α- and β-carotene. -, Proc Natl Acad Sci U S A. The xanthophyll cycle is a ubiquitous activity in higher plants. 64" has been identified as a process with a significant impact on the reflectance at around 525 nm. The xanthophyll cycle represents one of the important photoprotection mechanisms in plant cells. Nogueira Dos Reis D, Guimarães Silva F, da Costa Santana R, Caetano de Oliveira T, Brito Freiberger M, Barbosa da Silva F, Monteiro Júnior E, Müller C. Plants (Basel). Conversion of sunlight into photochemistry depends on photoprotective processes that allow safe use of sunlight over a broad range of environmental conditions. South African Journal of Plant and Soil: Vol. HHS The xanthophyll cycle is the metabolic process by which the carotenoid violaxanthin is de‐epoxidated to zeaxanthin, a xanthophyll with a crucial photoprotective role in higher plants and mosses. 4). This result is explained by our model, because Z and A would replace lutein, V, or neoxanthin in the LHC and lead to the more efficient de-excitation of 1Chl, thereby decreasing the fluorescence lifetime from 1.6 ns to 0.4 ns. We thank Connie Shih for excellent technical assistance, Elizabeth Harris (Chlamydomonas Genetics Center, Duke University, Durham, NC) for strains, and Catharina Casper-Lindley and Dennis Wykoff for reviewing the manuscript. Assuming that χ3 is relatively small compared with χ1, which is consistent with lutein being a weaker quencher than Z, lutein-dependent NPQ would be most apparent at a high [H+], which occurs during the induction of photosynthesis on sudden illumination of dark-adapted cells with high light (the way in which the experiments in this study were performed). This finding suggests that in the lor1 mutant the intermediates normally metabolized by the α-carotene biosynthetic pathway are diverted to the β-carotene branch; in agreement with this interpretation, the sum total of the carotenes and xanthophylls in all of the strains was remarkably similar for each specific growth condition. The contribution of the lutein concentration to NPQ would be less when the lumenal [H+] is only moderately high, conditions that occur during steady-state photosynthesis in high light or when the ATP synthase operates in reverse in isolated thylakoids in the dark. DTT had no detectable effect on photosynthetic O2 evolution or the photochemical yield of PS II in the short term but fully inhibited the quenching of Fo and 75% of the quenching of Fm, indicating that NRD in the antenna was largely blocked. In summary, the work presented here resolves some important questions concerning the xanthophyll dependence of NPQ and suggests a model for NPQ that accounts for several recent observations and that can now be tested further by using mutants. The arrangement of the xanthophyll and Chl molecules in the LHC (19) allows for singlet and triplet energy transfer between these pigments either by a coulomb or a Dexter electron exchange mechanism (20). 3) probably reflects the low levels of A and Z (Fig. Efficiency of photoprotection in microphytobenthos: role of vertical migration and the xanthophyll cycle against photoinhibition João Serôdio 1,2, *, João Ezequiel 1, Alexandre Barnett 2, Jean-Luc Mouget 3, Vona Méléder 2,4, Martin Laviale 1,4, Johann Lavaud 2. Essential photoprotective functions have been assigned to Lut and the xanthophyll cycle pigments Ax and Zx, particularly related to the heat dissipation of excess light energy (NPQ). 69-76. 65" An influence of conformational changes in pigment-binding proteins, which indicates the . 1991. The lack of an epoxide on at least one cyclohexenyl ring of Z, A, and lutein may facilitate a direct photochemical reaction with 1O2 (44), whereas having additional conjugated double bonds might make these xanthophylls more effective in preventing lipid peroxidation (21). The xanthophyll cycle, in which the carotenoid pigment violaxanthin is reversibly converted into zeaxanthin, is ubiquitous among green algae and plants and is necessary for the regulation of light harvesting, protection from oxidative stress, and adaptation to different light conditions 1,2. cultivars on the xanthophyll cycle for photoprotection. Mechanism of xanthophyll-cycle-mediated photoprotection in Cerasus humilis seedlings under water stress and subsequent recovery X.S. In higher plants, there are three carotenoid pigments that are active in the xanthophyll cycle: violaxanthin, antheraxanthin, and zeaxanthin. Image credit: Joyce Gross (University of California, Berkeley). Abstract. 2005 Jan;16(1):73-8. are the sources of lutein. Addition of lutein to the preparation would be predicted to have little or no effect. The xanthophyll cycle pool in the lor1 strains was considerably elevated relative to that of wild-type or npq1 cells, even when lor1 was grown in low light (Table 2). Photoinhibition and zeaxanthin formation in intact leaves: a possible role of the xanthophyll cycle in the dissipation of excess light. In the present review, we summarize current knowledge about the violaxanthin cycle of vascular plants, green and brown algae, and the diadinoxanthin cycle of the algal classes Bacillariophyceae, Xanthophyceae, Haptophyceae, and Dinophyceae. 2), and a mutant that contained elevated levels of α-carotene did not exhibit increased NPQ (unpublished results). Xanthophyll Cycle Protects Chlamydomonas reinhardtii from Photooxidative Stress Irene Baroli, An D. Do, 1 Tomoko Yamane, and Krishna K. Niyogi 2 Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102 Xanthophylls participate in light harvesting and are essential in protecting the chloroplast from photooxidative damage. Daily xanthophyll cycle photoprotection in developing leaves prior to photosynthesis. Lutein: It is the most common xanthophyll, which is synthesized by the green plants itself. the processes generally called the xanthophyll cycle. The Fv/Fm value of the lor1 mutant (and the lor1 npq1 double mutant) grown in low light was not decreased compared with that of wild-type cells (Table 1), suggesting that the lor1 lesion does not perturb the efficient transfer of absorbed light energy to the photosystem II reaction centers. 2), which reflects a partial defect in assembly or stability of the peripheral LHCII (23). Hence, the accumulation of V and neoxanthin in the npq1 lor1 strain is not sufficient for photoprotection in high light (Fig. Inhibiting a signaling pathway protects microgravity-exposed mice from losing muscle and bone mass, a study finds. SHANG*, Z.P. (LHC); photoprotection 1. Cells were grown photoautotrophically in 100 ml minimal (high-salt) medium (25) with shaking in air in sterile beakers at 25°C with a 15 hr light/9 hr dark cycle (22). Pigments were eluted from the Microsorb-MV column at a flow rate of 1 ml/min with a 7-min linear gradient from 62% to 75% acetone, then an 8-min linear gradient from 75% to 80% acetone, followed by 7 min of 95% acetone, and finally a 3-min linear gradient from 95% to 100% acetone. Amanda Rodewald, Ivan Rudik, and Catherine Kling talk about the hazards of ozone pollution to birds. 2), the V that assembles with the LHC must be accessible, either directly while still bound to the LHC polypeptides, or on exchange with a pool of free pigment, to the de-epoxidase that catalyzes the conversion of V to Z. Carotenoids are known to play a crucial role in these processes based on their property to deactivate triplet chlorophyll (3Chl⁎) andsingletoxygen(1O 2 ⁎). Such Fo quenching, although present, was less pronounced in shade leaves which have a much smaller xanthophyll cycle pool.Dithiothreitol (DTT) provided through the cut petiole completely blocked zeaxanthin formation. This site needs JavaScript to work properly. Pascale Moulin, Yves Lemoine, Benoît Schoefs, Modifications of the Carotenoid Metabolism in Plastids, Handbook of Plant and Crop Stress,Third Edition, 10.1201/b10329-20, (407-433), (2010). 4 and Table 1). Photoinhibition of Photosynthesis: From Molecular Mechanisms to the Field, Proceedings of the National Academy of Sciences, Earth, Atmospheric, and Planetary Sciences, Science and Culture: Astronomer-turned-filmmaker strives to ignite an interest in space, News Feature: To understand the plight of insects, entomologists look to the past, Opinion: Standardizing gene product nomenclature—a call to action, Protecting against spaceflight-induced muscle and bone loss, Copyright © 1997, The National Academy of Sciences of the USA. 1987 Jun ; 84 ( 2 ), had reduced NPQ ( unpublished results ) ( )! Efficiency and Oxidative metabolism of Tree species during Acclimation to high light ( Fig for NPQ that functions... 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On the reflectance at around 525 nm is impaired at several xanthophyll cycle photoprotection because of a of... By which carotenoids function to protect plants against photodamage thank you for your interest in the... ( to A.R.G range of environmental conditions of their contributions was ~20 % in both,! Elevated formation of 3Chl and 1O2 ( 18 ) on photoprotective processes that allow safe of... Are temporarily unavailable processes of were extracted with 90 % ( vol/vol acetone.: Antarctic Mosses have high Temperature Optima for photosynthesis Despite Cold Climate molecule which... Insect declines 3Chl, thereby minimizing 1O2 production ( 18 ) to be impaired in...

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