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Wang A, Siegwolf RTW, Joseph J, Thomas FM, Werner W, Gessler A, Rigling A, Schaub M, Saurer M, Li MH, Lehmann MM. Effects of soil moisture, needle age and leaf morphology on carbon and oxygen uptake, incorporation and allocation: a dual labeling approach with 13CO2 and H218O in foliage of a coniferous forest. TREE PHYSIOLOGY 2021; 41:50-62. [PMID: 32879961 DOI: 10.1093/treephys/tpaa114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 08/25/2020] [Indexed: 06/11/2023]
Abstract
The carbon and oxygen isotopic composition of water and assimilates in plants reveals valuable information on plant responses to climatic conditions. Yet, the carbon and oxygen uptake, incorporation and allocation processes determining isotopic compositions are not fully understood. We carried out a dual-isotope labeling experiment at high humidity with 18O-enriched water (H218O) and 13C-enriched CO2 (13CO2) with attached Scots pine (Pinus sylvestris L.) branches and detached twigs of hemiparasitic mistletoes (Viscum album ssp. austriacum) in a naturally dry coniferous forest, where also a long-term irrigation takes place. After 4 h of label exposure, we sampled previous- and recent-year leaves, twig phloem and twig xylem over 192 h for the analysis of isotope ratios in water and assimilates. For both species, the uptake into leaf water and the incorporation of the 18O-label into leaf assimilates was not influenced by soil moisture, while the 13C-label incorporation into assimilates was significantly higher under irrigation compared with control dry conditions. Species-specific differences in leaf morphology or needle age did not affect 18O-label uptake into leaf water, but the incorporation of both tracers into assimilates was two times lower in mistletoe than in pine. The 18O-label allocation in water from pine needles to twig tissues was two times higher for phloem than for xylem under both soil moisture conditions. In contrast, the allocation of both tracers in pine assimilates were similar and not affected by soil moisture, twig tissue or needle age. Soil moisture effects on 13C-label but not on 18O-label incorporation into assimilates can be explained by the stomatal responses at high humidity, non-stomatal pathways for water and isotope exchange reactions. Our results suggest that non-photosynthetic 18O-incorporation processes may have masked prevalent photosynthetic processes. Thus, isotopic variation in leaf water could also be imprinted on assimilates when photosynthetic assimilation rates are low.
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Affiliation(s)
- Ao Wang
- Forest Dynamics, Swiss Federal Research Institute WSL Birmensdorf, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
- Institute of Terrestrial Ecosystems, ETH Zurich, Universitaetsstrasse 16, 8092 Zurich, Switzerland
| | - Rolf T W Siegwolf
- Forest Dynamics, Swiss Federal Research Institute WSL Birmensdorf, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Jobin Joseph
- Forest Dynamics, Swiss Federal Research Institute WSL Birmensdorf, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Frank M Thomas
- Geobotany, University of Trier, Behringstrasse 21, 54296 Trier, Germany
| | - Willy Werner
- Geobotany, University of Trier, Behringstrasse 21, 54296 Trier, Germany
| | - Arthur Gessler
- Forest Dynamics, Swiss Federal Research Institute WSL Birmensdorf, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
- Institute of Terrestrial Ecosystems, ETH Zurich, Universitaetsstrasse 16, 8092 Zurich, Switzerland
| | - Andreas Rigling
- Forest Dynamics, Swiss Federal Research Institute WSL Birmensdorf, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
- Institute of Terrestrial Ecosystems, ETH Zurich, Universitaetsstrasse 16, 8092 Zurich, Switzerland
| | - Marcus Schaub
- Forest Dynamics, Swiss Federal Research Institute WSL Birmensdorf, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Matthias Saurer
- Forest Dynamics, Swiss Federal Research Institute WSL Birmensdorf, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Mai-He Li
- Forest Dynamics, Swiss Federal Research Institute WSL Birmensdorf, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Marco M Lehmann
- Forest Dynamics, Swiss Federal Research Institute WSL Birmensdorf, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland
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Cirocco RM, Facelli JM, Watling JR. Does light influence the relationship between a native stem hemiparasite and a native or introduced host? ANNALS OF BOTANY 2016; 117:521-31. [PMID: 26832961 PMCID: PMC4765548 DOI: 10.1093/aob/mcv193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 11/23/2015] [Indexed: 05/29/2023]
Abstract
BACKGROUND AND AIMS There have been very few studies investigating the influence of light on the effects of hemiparasitic plants on their hosts, despite the fact that hemiparasites are capable of photosynthesis but also access carbon (C) from their host. In this study we manipulated light availability to limit photosynthesis in an established hemiparasite and its hosts, and determined whether this affected the parasite's impact on growth and performance of two different hosts. We expected that limiting light and reducing autotrophic C gain in the parasite (and possibly increasing its heterotrophic C gain) would lead to an increased impact on host growth and/or host photosynthesis in plants grown in low (LL) relative to high light (HL). METHODS The Australian native host Leptospermum myrsinoides and the introduced host Ulex europaeus were either infected or not infected with the native stem hemiparasite Cassytha pubescens and grown in either HL or LL. Photosynthetic performance, nitrogen status and growth of hosts and parasite were quantified. Host water potentials were also measured. KEY RESULTS In situ midday electron transport rates (ETRs) of C. pubescens on both hosts were significantly lower in LL compared with HL, enabling us to investigate the impact of the reduced level of parasite autotrophy on growth of hosts. Despite the lower levels of photosynthesis in the parasite, the relative impact of infection on host biomass was the same in both LL and HL. In fact, biomass of L. myrsinoides was unaffected by infection in either HL or LL, while biomass of U. europaeus was negatively affected by infection in both treatments. This suggests that although photosynthesis of the parasite was lower in LL, there was no additional impact on host biomass in LL. In addition, light did not affect the amount of parasite biomass supported per unit host biomass in either host, although this parameter was slightly lower in LL than HL for U. europaeus (P = 0·073). We also found no significant enhancement of host photosynthesis in response to infection in either host, regardless of light treatment. CONCLUSIONS Despite lower photosynthetic rates in LL, C. pubescens did not increase its dependency on host C to the point where it affected host growth or photosynthesis. The impact of C. pubescens on host growth would be similar in areas of high and low light availability in the field, but the introduced host is more negatively affected by infection.
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Affiliation(s)
| | - José Maria Facelli
- School of Biological Sciences, The University of Adelaide, Adelaide 5005, Australia and
| | - Jennifer Robyn Watling
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne NE1 8ST, UK
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Involvement of a Second Xanthophyll Cycle in Non-Photochemical Quenching of Chlorophyll Fluorescence: The Lutein Epoxide Story. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2014. [DOI: 10.1007/978-94-017-9032-1_12] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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García-Plazaola JI, Esteban R, Fernández-Marín B, Kranner I, Porcar-Castell A. Thermal energy dissipation and xanthophyll cycles beyond the Arabidopsis model. PHOTOSYNTHESIS RESEARCH 2012; 113:89-103. [PMID: 22772904 DOI: 10.1007/s11120-012-9760-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 06/18/2012] [Indexed: 05/20/2023]
Abstract
Thermal dissipation of excitation energy is a fundamental photoprotection mechanism in plants. Thermal energy dissipation is frequently estimated using the quenching of the chlorophyll fluorescence signal, termed non-photochemical quenching. Over the last two decades, great progress has been made in the understanding of the mechanism of thermal energy dissipation through the use of a few model plants, mainly Arabidopsis. Nonetheless, an emerging number of studies suggest that this model represents only one strategy among several different solutions for the environmental adjustment of thermal energy dissipation that have evolved among photosynthetic organisms in the course of evolution. In this review, a detailed analysis of three examples highlights the need to use models other than Arabidopsis: first, overwintering evergreens that develop a sustained form of thermal energy dissipation; second, desiccation tolerant plants that induce rapid thermal energy dissipation; and third, understorey plants in which a complementary lutein epoxide cycle modulates thermal energy dissipation. The three examples have in common a shift from a photosynthetically efficient state to a dissipative conformation, a strategy widely distributed among stress-tolerant evergreen perennials. Likewise, they show a distinct operation of the xanthophyll cycle. Expanding the list of model species beyond Arabidopsis will enhance our knowledge of these mechanisms and increase the synergy of the current studies now dispersed over a wide number of species.
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Affiliation(s)
- José Ignacio García-Plazaola
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Apdo 644, 48080, Bilbao, Spain.
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Seasonal changes in the excess energy dissipation from Photosystem II antennae in overwintering evergreen broad-leaved trees Quercus myrsinaefolia and Machilus thunbergii. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2011; 104:348-56. [DOI: 10.1016/j.jphotobiol.2010.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 12/01/2010] [Accepted: 12/01/2010] [Indexed: 11/23/2022]
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Savitch LV, Ivanov AG, Krol M, Sprott DP, Oquist G, Huner NPA. Regulation of energy partitioning and alternative electron transport pathways during cold acclimation of lodgepole pine is oxygen dependent. PLANT & CELL PHYSIOLOGY 2010; 51:1555-70. [PMID: 20630988 DOI: 10.1093/pcp/pcq101] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Second year needles of Lodgepole pine (Pinus contorta L.) were exposed for 6 weeks to either simulated control summer ['summer'; 25 °C/250 photon flux denisty (PFD)], autumn ('autumn'; 15°C/250 PFD) or winter conditions ('winter'; 5 °C/250 PFD). We report that the proportion of linear electron transport utilized in carbon assimilation (ETR(CO2)) was 40% lower in both 'autumn' and 'winter' pine when compared with the 'summer' pine. In contrast, the proportion of excess photosynthetic linear electron transport (ETR(excess)) not used for carbon assimilation within the total ETR(Jf) increased by 30% in both 'autumn' and 'winter' pine. In 'autumn' pine acclimated to 15°C, the increased amounts of 'excess' electrons were directed equally to 21 kPa O2-dependent and 2 kPa O2-dependent alternative electron transport pathways and the fractions of excitation light energy utilized by PSII photochemistry (Φ(PSII)), thermally dissipated through Φ(NPQ) and dissipated by additional quenching mechanism(s) (Φ(f,D)) were similar to those in 'summer' pine. In contrast, in 'winter' needles acclimated to 5 °C, 60% of photosynthetically generated 'excess' electrons were utilized through the 2 kPa O2-dependent electron sink and only 15% by the photorespiratory (21 kPa O2) electron pathway. Needles exposed to 'winter' conditions led to a 3-fold lower Φ(PSII), only a marginal increase in Φ(NPQ) and a 2-fold higher Φ(f,D), which was O2 dependent compared with the 'summer' and 'autumn' pine. Our results demonstrate that the employment of a variety of alternative pathways for utilization of photosynthetically generated electrons by Lodgepole pine depends on the acclimation temperature. Furthermore, dissipation of excess light energy through constitutive non-photochemical quenching mechanisms is O2 dependent.
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Affiliation(s)
- Leonid V Savitch
- Agriculture and Agri-Food Canada, Eastern Cereal and Oilseed Research Centre, Ottawa, ON K1A0C6, Canada.
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Verhoeven A, Osmolak A, Morales P, Crow J. Seasonal changes in abundance and phosphorylation status of photosynthetic proteins in eastern white pine and balsam fir. TREE PHYSIOLOGY 2009; 29:361-74. [PMID: 19203960 DOI: 10.1093/treephys/tpn031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
During winter, the light-harvesting complexes of evergreen plants change function from energy-harvesting to energy-dissipating centers. The goal of our study was to monitor changes in the composition of the photosynthetic apparatus that accompany these functional changes. Seasonal changes in chlorophyll fluorescence, pigment concentration, and abundance and phosphorylation status of photosynthetic proteins in Pinus strobus L. (sun-exposed trees) and Abies balsamea (L.) P. Mill. (sun-exposed and shaded trees) were examined in the cold winter climate of Minnesota. Results indicated typical seasonal changes in chlorophyll fluorescence and pigment concentration, with sustained reduced photosystem II (PSII) efficiency during winter, accompanied by retention of zeaxanthin and antheraxanthin, and winter increases in the pool of xanthophyll cycle pigments and lutein. In sun-exposed trees, all photosynthetic proteins that were monitored decreased in relative abundance during winter, although two light-harvesting chlorophyll a/b binding proteins (Lhcb2 and Lhcb5), and the PsbS protein, were enriched in non-summer months, suggesting a role for these proteins in winter acclimation. In contrast, shaded trees maintained most of their protein throughout winter, with reductions occurring in spring. Thylakoid protein phosphorylation data suggest winter increases in the phosphorylation of a PSII core protein, PsbH, in sun-exposed trees, and increases in phosphorylation of all PSII core proteins in shaded trees.
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Affiliation(s)
- Amy Verhoeven
- Department of Biology, University of St. Thomas, St. Paul, MN 55105, USA.
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Esteban R, Jiménez MS, Morales D, Jiménez ET, Hormaetxe K, Becerril JM, Osmond B, García-Plazaola JI. Short- and long-term modulation of the lutein epoxide and violaxanthin cycles in two species of the Lauraceae: sweet bay laurel (Laurus nobilis L.) and avocado (Persea americana Mill.). PLANT BIOLOGY (STUTTGART, GERMANY) 2008; 10:288-297. [PMID: 18426476 DOI: 10.1111/j.1438-8677.2008.00036.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Short- and long-term responses of the violaxanthin (V) and lutein epoxide (Lx) cycles were studied in two species of Lauraceae: sweet bay laurel (Laurus nobilis L.) and avocado (Persea americana L.). The Lx content exceeded the V content in shade leaves of both species. Both Lx and V were de-epoxidised on illumination, but only V was fully restored by epoxidation in low light. Violaxanthin was preferentially de-epoxidised in low light in L. nobilis. This suggests that Lx accumulates with leaf ageing, partly because its conversion to lutein is limited in shade. After exposure to strong light, shade leaves of avocado readjusted the total pools of alpha- and beta-xanthophyll cycles by de novo synthesis of antheraxanthin, zeaxanthin and lutein. This occurred in parallel with a sustained depression of F(v)/F(m). In Persea indica, a closely related but low Lx species, F(v)/F(m) recovered faster after a similar light treatment, suggesting the involvement of the Lx cycle in sustained energy dissipation. Furthermore, the seasonal correlation between non-reversible Lx and V photoconversions and pre-dawn F(v)/F(m) in sun leaves of sweet bay supported the conclusion that the Lx cycle is involved in a slowly reversible downregulation of photosynthesis analogous to the V cycle.
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Affiliation(s)
- R Esteban
- Department of Plant Biology and Ecology, UPV/EHU, Bilbao, Spain
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Matsubara S, Krause GH, Seltmann M, Virgo A, Kursar TA, Jahns P, Winter K. Lutein epoxide cycle, light harvesting and photoprotection in species of the tropical tree genus Inga. PLANT, CELL & ENVIRONMENT 2008; 31:548-561. [PMID: 18208510 DOI: 10.1111/j.1365-3040.2008.01788.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Dynamics and possible function of the lutein epoxide (Lx) cycle, that is, the reversible conversion of Lx to lutein (L) in the light-harvesting antennae, were investigated in leaves of tropical tree species. Photosynthetic pigments were quantified in nine Inga species and species from three other genera. In Inga, Lx levels were high in shade leaves (mostly above 20 mmol mol(-1) chlorophyll) and low in sun leaves. In Virola surinamensis, both sun and shade leaves exhibited very high Lx contents (about 60 mmol mol(-1) chlorophyll). In Inga marginata grown under high irradiance, Lx slowly accumulated within several days upon transfer to deep shade. When shade leaves of I. marginata were briefly exposed to the sunlight, both violaxanthin and Lx were quickly de-epoxidized. Subsequently, overnight recovery occurred only for violaxanthin, not for Lx. In such leaves, containing reduced levels of Lx and increased levels of L, chlorophyll fluorescence induction showed significantly slower reduction of the photosystem II electron acceptor, Q(A), and faster formation as well as a higher level of non-photochemical quenching. The results indicate that slow Lx accumulation in Inga leaves may improve light harvesting under limiting light, while quick de-epoxidation of Lx to L in response to excess light may enhance photoprotection.
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Affiliation(s)
- Shizue Matsubara
- Phytosphere Institute (ICG-3), Research Centre Jülich, 52425 Jülich, Germany.
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Yokono M, Akimoto S, Tanaka A. Seasonal changes of excitation energy transfer and thylakoid stacking in the evergreen tree Taxus cuspidata: How does it divert excess energy from photosynthetic reaction center? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:379-87. [DOI: 10.1016/j.bbabio.2008.01.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 01/23/2008] [Accepted: 01/24/2008] [Indexed: 10/22/2022]
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Characteristics and Species-Dependent Employment of Flexible Versus Sustained Thermal Dissipation and Photoinhibition. PHOTOPROTECTION, PHOTOINHIBITION, GENE REGULATION, AND ENVIRONMENT 2008. [DOI: 10.1007/1-4020-3579-9_4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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García-Plazaola JI, Matsubara S, Osmond CB. The lutein epoxide cycle in higher plants: its relationships to other xanthophyll cycles and possible functions. FUNCTIONAL PLANT BIOLOGY : FPB 2007; 34:759-773. [PMID: 32689404 DOI: 10.1071/fp07095] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Accepted: 06/08/2007] [Indexed: 05/21/2023]
Abstract
Several xanthophyll cycles have been described in photosynthetic organisms. Among them, only two are present in higher plants: the ubiquitous violaxanthin (V) cycle, and the taxonomically restricted lutein epoxide (Lx) cycle, whereas four cycles seem to occur in algae. Although V is synthesised through the β-branch of the carotenoid biosynthetic pathway and Lx is the product of the α-branch; both are co-located in the same sites of the photosynthetic pigment-protein complexes isolated from thylakoids. Both xanthophylls are also de-epoxidised upon light exposure by the same enzyme, violaxanthin de-epoxidase (VDE) leading to the formation of zeaxanthin (Z) and lutein (L) at comparable rates. In contrast with VDE, the reverse reaction presumably catalysed by zeaxanthin epoxidase (ZE), is much slower (or even inactive) with L than with antheraxanthin (A) or Z. Consequently many species lack Lx altogether, and although the presence of Lx shows an irregular taxonomical distribution in unrelated taxa, it has a high fidelity at family level. In those plants which accumulate Lx, variations in ZE activity in vivo mean that a complete Lx-cycle occurs in some (with Lx pools being restored overnight), whereas in others a truncated cycle is observed in which VDE converts Lx into L, but regeneration of Lx by ZE is extremely slow. Accumulation of Lx to high concentrations is found most commonly in old leaves in deeply shaded canopies, and the Lx cycle in these leaves is usually truncated. This seemingly anomalous situation presumably arises because ZE has a low but finite affinity for L, and because deeply shaded leaves are not often exposed to light intensities strong enough to activate VDE. Notably, both in vitro and in vivo studies have recently shown that accumulation of Lx can increase the light harvesting efficiency in the antennae of PSII. We propose a model for the truncated Lx cycle in strong light in which VDE converts Lx to L which then occupies sites L2 and V1 in the light-harvesting antenna complex of PSII (Lhcb), displacing V and Z. There is correlative evidence that this photoconverted L facilitates energy dissipation via non-photochemical quenching and thereby converts a highly efficient light harvesting system to an energy dissipating system with improved capacity to engage photoprotection. Operation of the α- and β-xanthophyll cycles with different L and Z epoxidation kinetics thus allows a combination of rapidly and slowly reversible modulation of light harvesting and photoprotection, with each cycle having distinct effects. Based on the patchy taxonomical distribution of Lx, we propose that the presence of Lx (and the Lx cycle) could be the result of a recurrent mutation in the epoxidase gene that increases its affinity for L, which is conserved whenever it confers an evolutionary advantage.
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Affiliation(s)
| | - Shizue Matsubara
- Institut Phytosphäre (ICG3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - C Barry Osmond
- School of Biochemistry and Molecular Biology, Australian National University, Canberra, ACT 0200, Australia
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Matsubara S, Morosinotto T, Osmond CB, Bassi R. Short- and long-term operation of the lutein-epoxide cycle in light-harvesting antenna complexes. PLANT PHYSIOLOGY 2007; 144:926-41. [PMID: 17384157 PMCID: PMC1914152 DOI: 10.1104/pp.107.099077] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Accepted: 03/16/2007] [Indexed: 05/14/2023]
Abstract
The lutein-5,6-epoxide (Lx) cycle operates in some plants between lutein (L) and its monoepoxide, Lx. Whereas recent studies have established the photoprotective roles of the analogous violaxanthin cycle, physiological functions of the Lx cycle are still unknown. In this article, we investigated the operation of the Lx cycle in light-harvesting antenna complexes (Lhcs) of Inga sapindoides Willd, a tropical tree legume accumulating substantial Lx in shade leaves, to identify the xanthophyll-binding sites involved in short- and long-term responses of the Lx cycle and to analyze the effects on light-harvesting efficiency. In shade leaves, Lx was converted into L upon light exposure, which then replaced Lx in the peripheral V1 site in trimeric Lhcs and the internal L2 site in both monomeric and trimeric Lhcs, leading to xanthophyll composition resembling sun-type Lhcs. Similar to the violaxanthin cycle, the Lx cycle was operating in both photosystems, yet the light-induced Lx --> L conversion was not reversible overnight. Interestingly, the experiments using recombinant Lhcb5 reconstituted with different Lx and/or L levels showed that reconstitution with Lx results in a significantly higher fluorescence yield due to higher energy transfer efficiencies among chlorophyll (Chl) a molecules, as well as from xanthophylls to Chl a. Furthermore, the spectroscopic analyses of photosystem I-LHCI from I. sapindoides revealed prominent red-most Chl forms, having the lowest energy level thus far reported for higher plants, along with reduced energy transfer efficiency from antenna pigments to Chl a. These results are discussed in the context of photoacclimation and shade adaptation.
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Affiliation(s)
- Shizue Matsubara
- Phytosphäre Institut (Institut für Chemie und Dynamik der Geosphäre-3), Forschungszentrum Jülich, 52425 Juelich, Germany.
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Logan BA, Kornyeyev D, Hardison J, Holaday AS. The role of antioxidant enzymes in photoprotection. PHOTOSYNTHESIS RESEARCH 2006; 88:119-32. [PMID: 16622785 DOI: 10.1007/s11120-006-9043-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Accepted: 01/11/2006] [Indexed: 05/08/2023]
Abstract
The enzymatic component of the antioxidant system is discussed as one of the defensive mechanisms providing protection against excessive light absorption in plants. We present an analysis of attempts to improve stress tolerance by means of the creation of transgenic plants with elevated antioxidant enzyme activities and conclude that the effect of such transgenic manipulation strongly depends on the manner in which the stress is imposed. The following factors may diminish the differences in photosynthetic performance between transgenic plants and wild type under field conditions: effective functioning of the thermal dissipation mechanisms providing a primary line of defense against excessive light, long-term adjustments of the antioxidant system and other photoprotective mechanisms, the relatively low level of control over electron transport exerted by the Water-Water cycle, especially under warm conditions, and a decrease in the content of the transgenic product during leaf aging.
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Affiliation(s)
- Barry A Logan
- Department of Biology, Bowdoin College, Brunswick, ME 04011, USA. blogan@bowdoin. edu
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Demmig-Adams B, Adams WW. Photoprotection in an ecological context: the remarkable complexity of thermal energy dissipation. THE NEW PHYTOLOGIST 2006; 172:11-21. [PMID: 16945085 DOI: 10.1111/j.1469-8137.2006.01835.x] [Citation(s) in RCA: 374] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
This review places photoprotection into the context of ecology and species diversity. The focus is on photoprotection via the safe removal - as thermal energy - of excess solar energy absorbed by the light collecting system, which counteracts the formation of reactive oxygen species. An update on the surprisingly complex, multiple variations of thermal energy dissipation is presented, placing these different forms into ecological and genetic contexts. Zeaxanthin-facilitated, flexible thermal dissipation associated with the PsbS protein and controlled by the trans-thylakoid pH gradient apparently occurs ubiquitously in plants, and can become sustained (and thus less flexible) at low temperatures. Long-lived, slow-growing plants with low intrinsic capacities for photosynthesis have greater capacities for this flexible dissipation than short-lived, fast-growing species. Furthermore, potent, but inflexible (zeaxanthin-facilitated) thermal dissipation, prominent in evergreen species under prolonged environmental stress, is characterized with respect to the involvement of photosystem II core rearrangement and/or degradation as well as the absence of control by trans-thylakoid pH and, possibly, PsbS. A role of PsbS-related proteins in photoprotection is discussed.
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Affiliation(s)
- Barbara Demmig-Adams
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309-0334, USA.
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Dall'Osto L, Caffarri S, Bassi R. A mechanism of nonphotochemical energy dissipation, independent from PsbS, revealed by a conformational change in the antenna protein CP26. THE PLANT CELL 2005; 17:1217-32. [PMID: 15749754 PMCID: PMC1087998 DOI: 10.1105/tpc.104.030601] [Citation(s) in RCA: 185] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2004] [Accepted: 02/09/2005] [Indexed: 05/18/2023]
Abstract
The regulation of light harvesting in higher plant photosynthesis, defined as stress-dependent modulation of the ratio of energy transfer to the reaction centers versus heat dissipation, was studied by means of carotenoid biosynthesis mutants and recombinant light harvesting complexes (LHCs) with modified chromophore binding. The npq2 mutant of Arabidopsis thaliana, blocked in the biosynthesis of violaxanthin and thus accumulating zeaxanthin, was shown to have a lower fluorescence yield of chlorophyll in vivo and, correspondingly, a higher level of energy dissipation, with respect to the wild-type strain and npq1 mutant, the latter of which is incapable of zeaxanthin accumulation. Experiments on purified thylakoid membranes from all three mutants showed that the major source of the difference between the npq2 and wild-type preparations was a change in pigment to protein interactions, which can explain the lower chlorophyll fluorescence yield in the npq2 samples. Analysis of the xanthophyll binding LHC proteins showed that the Lhcb5 photosystem II subunit (also called CP26) undergoes a change in its pI upon binding of zeaxanthin. The same effect was observed in wild-type CP26 upon treatment that leads to the accumulation of zeaxanthin in the membrane and was interpreted as the consequence of a conformational change. This hypothesis was confirmed by the analysis of two recombinant proteins obtained by overexpression of the Lhcb5 apoprotein in Escherichia coli and reconstitution in vitro with either violaxanthin or zeaxanthin. The V and Z containing pigment-protein complexes obtained by this procedure showed different pIs and high and low fluorescence yields, respectively. These results confirm that LHC proteins exist in multiple conformations, an idea suggested by previous spectroscopic measurements (Moya et al., 2001), and imply that the switch between the different LHC protein conformations is activated by the binding of zeaxanthin to the allosteric site L2. The results suggest that the quenching process induced by the accumulation of zeaxanthin contributes to qI, a component of NPQ whose origin was previously poorly understood.
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Affiliation(s)
- Luca Dall'Osto
- Dipartimento Scientifico e Tecnologico, Università di Verona, 37134, Verona, Italy
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Matsubara S, Chow WS. Populations of photoinactivated photosystem II reaction centers characterized by chlorophyll a fluorescence lifetime in vivo. Proc Natl Acad Sci U S A 2004; 101:18234-9. [PMID: 15601775 PMCID: PMC539729 DOI: 10.1073/pnas.0403857102] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2004] [Indexed: 11/18/2022] Open
Abstract
Photosystem (PS) II centers, which split water into oxygen, protons, and electrons during photosynthesis, require light but are paradoxically inactivated by it. Prolonged light exposure concomitantly decreased both the functional fraction of PSII reaction centers and the integral PSII chlorophyll (Chl) a fluorescence lifetime in leaf segments of Capsicum annuum L. Acceleration of photoinactivation of PSII by a pretreatment with the inhibitors/uncoupler lincomycin, DTT, or nigericin further reduced PSII Chl a fluorescence lifetimes. A global analysis of fluorescence lifetime distributions revealed the presence of at least two distinct populations of photoinactivated PSII centers, one at 1.25 ns, and the other at 0.58 ns. Light treatment first increased the 1.25-ns component, a weak quencher, at the expense of a component at 2.22 ns corresponding to functional PSII centers. The 0.58-ns component, a strong quencher, emerged later than the 1.25-ns component. The strongly quenching PSII reaction centers could serve to avoid further damage to themselves and protect their functional neighbors by acting as strong energy sinks.
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Affiliation(s)
- Shizue Matsubara
- Photobioenergetics Group, Research School of Biological Sciences, Australian National University, G.P.O. Box 475, Canberra ACT 2601, Australia
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García-Plazaola JI, Hormaetxe K, Hernández A, Olano JM, Becerril JM. The lutein epoxide cycle in vegetative buds of woody plants. FUNCTIONAL PLANT BIOLOGY : FPB 2004; 31:815-823. [PMID: 32688952 DOI: 10.1071/fp04054] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2004] [Accepted: 05/12/2004] [Indexed: 05/22/2023]
Abstract
Recent works have shown that two xanthophyll cycles operate simultaneously in several plant species: the ubiquitous violaxanthin + anteraxanthin + zeaxanthin (VAZ) cycle and the lutein epoxide (Lx) cycle. In the present work we tested for the presence of the Lx cycle in vegetative buds of woody plants. After an extensive screening of 130 species, we have shown that Lx is present in buds of many different plant species and leaf primordia are enriched in Lx compared with leaves. As a result, the Lx pool was higher than the violaxanthin (V) pool in several species. Although Lx can be potentially de-epoxidised in buds, light attenuation by scales inhibited the daily operation of the Lx cycle. This finding would imply that the Lx cycle is not involved in short-term reversible photoprotection in buds. However, a light-induced decrease in Lx was observed through the winter. An extensive screening of 130 species in 49 families conducted to elucidate the taxonomic extension of this cycle showed a widespread presence of the Lx cycle. The presence of Lx has a high fidelity at the family level, but its presence in unrelated taxa suggests that this character has appeared independently in several different groups of plants.
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Affiliation(s)
- José I García-Plazaola
- Department of Plant Biology and Ecology, University of the Basque Country EHU, Aptdo 644, E-48080 Bilbao, Spain
| | - Koldobika Hormaetxe
- Department of Plant Biology and Ecology, University of the Basque Country EHU, Aptdo 644, E-48080 Bilbao, Spain
| | - Antonio Hernández
- Department of Plant Biology and Ecology, University of the Basque Country EHU, Aptdo 644, E-48080 Bilbao, Spain
| | - José M Olano
- Área de Biología Vegetal, Departamento de Ciencias Agroforestales, Escuela de Ingenierías Agrarias, Los Pajaritos s/n, Soria, E-42003 Spain
| | - José M Becerril
- Department of Plant Biology and Ecology, University of the Basque Country EHU, Aptdo 644, E-48080 Bilbao, Spain
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ADAMS WILLIAMW, ZARTER CRYAN, EBBERT VOLKER, DEMMIG-ADAMS BARBARA. Photoprotective Strategies of Overwintering Evergreens. Bioscience 2004. [DOI: 10.1641/0006-3568(2004)054[0041:psooe]2.0.co;2] [Citation(s) in RCA: 186] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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