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Light Energy Partitioning under Various Environmental Stresses Combined with Elevated CO2 in Three Deciduous Broadleaf Tree Species in Japan. CLIMATE 2019. [DOI: 10.3390/cli7060079] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Understanding plant response to excessive light energy not consumed by photosynthesis under various environmental stresses, would be important for maintaining biosphere sustainability. Based on previous studies regarding nitrogen (N) limitation, drought in Japanese white birch (Betula platyphylla var. japonica), and elevated O3 in Japanese oak (Quercus mongolica var. crispula) and Konara oak (Q. serrata) under future-coming elevated CO2 concentrations, we newly analyze the fate of absorbed light energy by a leaf, partitioning into photochemical processes, including photosynthesis, photorespiration and regulated and non-regulated, non-photochemical quenchings. No significant increases in the rate of non-regulated non-photochemical quenching (JNO) were observed in plants grown under N limitation, drought and elevated O3 in ambient or elevated CO2. This suggests that the risk of photodamage caused by excessive light energy was not increased by environmental stresses reducing photosynthesis, irrespective of CO2 concentrations. The rate of regulated non-photochemical quenching (JNPQ), which contributes to regulating photoprotective thermal dissipation, could well compensate decreases in the photosynthetic electron transport rate through photosystem II (JPSII) under various environmental stresses, since JNPQ+JPSII was constant across the treatment combinations. It is noteworthy that even decreases in JNO were observed under N limitation and elevated O3, irrespective of CO2 conditions, which may denote a preconditioning-mode adaptive response for protection against further stress. Such an adaptive response may not fully compensate for the negative effects of lethal stress, but may be critical for coping with non-lethal stress and regulating homeostasis. Regarding the three deciduous broadleaf tree species, elevated CO2 appears not to influence the plant responses to environmental stresses from the viewpoint of susceptibility to photodamage.
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Canopy nitrogen distribution is optimized to prevent photoinhibition throughout the canopy during sun flecks. Sci Rep 2018; 8:503. [PMID: 29323155 PMCID: PMC5764975 DOI: 10.1038/s41598-017-18766-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 12/15/2017] [Indexed: 11/08/2022] Open
Abstract
As photoinhibition primarily reduces the photosynthetic light use efficiency at low light, sunfleck-induced photoinhibition might result in a fatal loss of carbon gain in the shade leaves within a canopy with barely positive carbon balance. We hypothesized that shade leaves at the lower canopy might retain a certain amount of leaf nitrogen (NL) to maintain energy consumption via electron transport, which contributes to circumventing photoinhibition during sunflecks to keep efficient utilization of low light during the rest period of daytime. We investigated excess energy production, a potential measure of susceptibility to photoinhibition, as a function of NL distribution within a Japanese oak canopy. Optimal NL distribution, which maximizes canopy carbon gain, may lead to a higher risk of photoinhibition in shade leaves during sunflecks. Conversely, uniform NL distribution would cause a higher risk of photoinhibition in sun leaves under the direct sunlight. Actual NL distribution equalized the risk of photoinhibition throughout the canopy indicated by the constant excess energy production at the highest light intensities that the leaves received. Such a homeostatic adjustment as a whole canopy concerning photoinhibition would be a key factor to explain why actual NL distribution does not maximize canopy carbon gain.
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Niinemets Ü. Within-Canopy Variations in Functional Leaf Traits: Structural, Chemical and Ecological Controls and Diversity of Responses. CANOPY PHOTOSYNTHESIS: FROM BASICS TO APPLICATIONS 2016. [DOI: 10.1007/978-94-017-7291-4_4] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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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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Mänd P, Hallik L, Peñuelas J, Kull O. Electron transport efficiency at opposite leaf sides: effect of vertical distribution of leaf angle, structure, chlorophyll content and species in a forest canopy. TREE PHYSIOLOGY 2013; 33:202-210. [PMID: 23185067 DOI: 10.1093/treephys/tps112] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We investigated changes in chlorophyll a fluorescence from alternate leaf surfaces to assess the intraleaf light acclimation patterns in combination with natural variations in radiation, leaf angles, leaf mass per area (LMA), chlorophyll content (Chl) and leaf optical parameters. Measurements were conducted on bottom- and top-layer leaves of Tilia cordata Mill. (a shade-tolerant sub-canopy species, sampled at heights of 11 and 16 m) and Populus tremula L. (a light-demanding upper canopy species, sampled at canopy heights of 19 and 26 m). The upper canopy species P. tremula had a six times higher PSII quantum yield (Φ(II)) and ratio of open reaction centres (qP), and a two times higher LMA than T. cordata. These species-specific differences were also present when the leaves of both species were in similar light conditions. Leaf adaxial/abaxial fluorescence ratio was significantly larger in the case of more horizontal leaves. Populus tremula (more vertical leaves), had smaller differences in fluorescence parameters between alternate leaf sides compared with T. cordata (more horizontal leaves). However, optical properties on alternate leaf sides showed a larger difference for P. tremula. Intraspecifically, the measured optical parameters were better correlated with LMA than with leaf Chl. Species-specific differences in leaf anatomy appear to enhance the photosynthetic potential of leaf biochemistry by decreasing the interception of excess light in P. tremula and increasing the light absorptance in T. cordata. Our results indicate that intraleaf light absorption gradient, described here as leaf adaxial/abaxial side ratio of chlorophyll a fluorescence, varies significantly with changes in leaf light environment in a multi-layer multi-species tree canopy. However, this variation cannot be described merely as a simple function of radiation, leaf angle, Chl or LMA, and species-specific differences in light acclimation strategies should also be considered.
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Affiliation(s)
- Pille Mänd
- Department of Botany, Institute of Ecology and Earth Sciences, Tartu University, Lai 40, Tartu 51005, Estonia.
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Way DA, Pearcy RW. Sunflecks in trees and forests: from photosynthetic physiology to global change biology. TREE PHYSIOLOGY 2012; 32:1066-81. [PMID: 22887371 DOI: 10.1093/treephys/tps064] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Sunflecks are brief, intermittent periods of high photon flux density (PFD) that can significantly improve carbon gain in shaded forest understories and lower canopies of trees. In this review, we discuss the physiological basis of leaf-level responses to sunflecks and the mechanisms plants use to tolerate sudden changes in PFD and leaf temperature induced by sunflecks. We also examine the potential effects of climate change stresses (including elevated temperatures, rising CO(2) concentrations and drought) on the ability of tree species to use sunflecks, and advocate more research to improve our predictions of seedling and tree carbon gain in future climates. Lastly, while we have the ability to model realistic responses of photosynthesis to fluctuating PFD, dynamic responses of photosynthesis to sunflecks are not accounted for in current models of canopy carbon uptake, which can lead to substantial overestimates of forest carbon fixation. Since sunflecks are a critical component of seasonal carbon gain for shaded leaves, sunfleck regimes and physiological responses to sunflecks should be incorporated into models to more accurately capture forest carbon dynamics.
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Affiliation(s)
- Danielle A Way
- Nicholas School of the Environment, Duke University, Durham, NC 27708, USA.
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Bonan GB, Lawrence PJ, Oleson KW, Levis S, Jung M, Reichstein M, Lawrence DM, Swenson SC. Improving canopy processes in the Community Land Model version 4 (CLM4) using global flux fields empirically inferred from FLUXNET data. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jg001593] [Citation(s) in RCA: 459] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Niinemets Ü, Copolovici L, Hüve K. High within-canopy variation in isoprene emission potentials in temperate trees: Implications for predicting canopy-scale isoprene fluxes. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010jg001436] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Schymanski SJ, Roderick ML, Sivapalan M, Hutley LB, Beringer J. A test of the optimality approach to modelling canopy properties and CO2 uptake by natural vegetation. PLANT, CELL & ENVIRONMENT 2007; 30:1586-98. [PMID: 17927696 DOI: 10.1111/j.1365-3040.2007.01728.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Photosynthesis provides plants with their main building material, carbohydrates, and with the energy necessary to thrive and prosper in their environment. We expect, therefore, that natural vegetation would evolve optimally to maximize its net carbon profit (NCP), the difference between carbon acquired by photosynthesis and carbon spent on maintenance of the organs involved in its uptake. We modelled N(CP) for an optimal vegetation for a site in the wet-dry tropics of north Australia based on this hypothesis and on an ecophysiological gas exchange and photosynthesis model, and compared the modelled CO2 fluxes and canopy properties with observations from the site. The comparison gives insights into theoretical and real controls on gas exchange and canopy structure, and supports the optimality approach for the modelling of gas exchange of natural vegetation. The main advantage of the optimality approach we adopt is that no assumptions about the particular vegetation of a site are required, making it a very powerful tool for predicting vegetation response to long-term climate or land use change.
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Affiliation(s)
- Stanislaus J Schymanski
- School of Environmental Systems Engineering, The University of Western Australia, Perth, Western Australia, Australia.
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Karageorgou P, Tziortzis I, Manetas Y. Are saturating pulses indeed saturating? Evidence for considerable PSII yield underestimation in leaves adapted to high levels of natural light. JOURNAL OF PLANT PHYSIOLOGY 2007; 164:1331-6. [PMID: 17074411 DOI: 10.1016/j.jplph.2006.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Accepted: 07/24/2006] [Indexed: 05/12/2023]
Abstract
The "saturating pulse" method of in vivo Chl fluorescence measurement has been widely used by physiologists and especially ecophysiologists, as it allows a simple, rapid and non-invasive assessment of PSII function and the allocation of absorbed energy into photochemical and non-photochemical processes. It is based on the accurate determination of the so-called Fm('), i.e. the fluorescence signal emitted when a "saturating" light pulse closes all PSII centers. In this methodological investigation, we examined whether the saturating pulse intensities required to obtain maximal fluorescence yields differ between leaves of various species receiving varying actinic light irradiances. It was shown that, in leaves adapted to comparatively high (yet realistic) levels of natural irradiances, the saturating pulses usually applied are not able to close all PSII reaction centers. As a result, there is a high risk of considerable Fm(') underestimation. Accordingly, the derived values of effective PSII yields and linear electron transport rates (ETR) are also underestimated, even at the highest saturation pulse levels afforded by commercial instruments. Since the extent of underestimation increases with actinic irradiance, the ETR versus light curves are considerably distorted. The possible reasons for the apparent inability of "saturating" pulses to close all PSII centers at high actinic light and the practical implications, especially in field work, are discussed.
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Affiliation(s)
- Panagiota Karageorgou
- Laboratory of Plant Physiology, Department of Biology, University of Patras, GR-26500 Patras, Greece
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García-Plazaola JI, Becerril JM, Hernández A, Niinemets Ü, Kollist H. Acclimation of antioxidant pools to the light environment in a natural forest canopy. THE NEW PHYTOLOGIST 2004; 163:87-97. [PMID: 33873782 DOI: 10.1111/j.1469-8137.2004.01096.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
• Leaf growth irradiance determines the pools of photoprotective molecules. We asked whether the potential for acclimation of antioxidant pool size to changes in the leaf light environment is affected by the position of the leaf within the canopy profile. • The study was conducted in a mixed canopy formed by Tilia cordata at the lower level and Populus tremula at the upper level. Leaves were either exposed to extra light or enclosed in shade bags. • Ascorbate, glutathione and α-tocopherol pools increased with growth irradiance. Only α-tocopherol increased in leaves of both species in response to extra light. The slope of tocopherol changes was positively correlated with growth irradiance in both species. It also correlated with the slope of xanthophyll cycle (VAZ, sum of violaxanthin, antheraxanthin and zeaxanthin) pool changes with cumulative extra light in T. cordata. • We conclude that α-tocopherol is the key antioxidant altering tolerance to high light, and that it may cooperate with zeaxanthin. The pools of hydrophilic antioxidants either acclimate more slowly, or their pools are large enough not to limit the overall acclimation to altered light environment.
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Affiliation(s)
| | - José María Becerril
- Departemento de Biología Vegetal y Ecología, Universidad del País Vasco, Aptdo 644, E-48080 Bilbao, Spain
| | - Antonio Hernández
- Departemento de Biología Vegetal y Ecología, Universidad del País Vasco, Aptdo 644, E-48080 Bilbao, Spain
- Present address: Dirección de Innovación y Desarrollo, OHL, Gobelas 35-37, El Plantío, E-28023 Madrid, Spain
| | - Ülo Niinemets
- Department of Plant Physiology, Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
- Centro di Ecologia Alpina, I-38040 Viote del Monte Bondone (TN), Italy
| | - Hannes Kollist
- Department of Plant Physiology, Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia
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Hormaetxe K, Hernández A, Becerril JM, García-Plazaola JI. Role of red carotenoids in photoprotection during winter acclimation in Buxus sempervirens leaves. PLANT BIOLOGY (STUTTGART, GERMANY) 2004; 6:325-332. [PMID: 15143441 DOI: 10.1055/s-2004-817883] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The red leaf coloration of several plant species during autumn and winter is due to the synthesis of phenolic compounds such as anthocyanins or red carotenoids. The latter occur very rarely and are non-ubiquitous and taxonomically restricted compounds. The present study shows that the leaves of common box ( Buxus sempervirens L.) accumulate red carotenoids (eschscholtzxanthin, monoanhydroeschscholtzxanthin, anhydroeschscholtzxanthin) as a response to photoinhibitory conditions during winter acclimation. These compounds are produced in a coordinated manner with the operation of other photoprotective systems: accumulation and sustained deepoxidation of VAZ pigments with a concomitant decrease in maximal photochemical efficiency, accumulation of alpha-tocopherol and a gradual decrease on chlorophyll content. All these processes were reversed when the photosynthetic tissues were transferred from photoinhibitory winter conditions to room temperature for 9 days. Buxus leaves showed a large degree of phenotype variation in the degree of reddening, ranging from green to orange. The differences in colour pattern were mainly due to differences in the accumulation of red carotenoids and xanthophyll esters. Red pigments were mainly anhydroeschscholtzxanthin and esters of eschscholtzxanthin. Conversely to fruit or petal chromoplasts, the plastids of red leaves in this species are not the terminal differentiated state but are able to redifferentiate again to chloroplasts. Their photoprotective role during winter as a light screen system or as antioxidants, in a similar way to other red pigments, and their implications on the wide ecological tolerance of this evergreen species are discussed.
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Affiliation(s)
- K Hormaetxe
- Department of Plant Biology and Ecology, Universidad del País Vasco-EHU, Bilbao, Spain
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Llorens L, Peñuelas J, Filella I. Diurnal and seasonal variations in the photosynthetic performance and water relations of two co-occurring Mediterranean shrubs, Erica multiflora and Globularia alypum. PHYSIOLOGIA PLANTARUM 2003; 118:84-95. [PMID: 12702017 DOI: 10.1034/j.1399-3054.2003.00174.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Diurnal and seasonal fluctuations in the photosynthetic performance and water relations of two co-occurring Mediterranean shrubs, Erica multiflora and Globularia alypum were monitored throughout two consecutive years at Garraf Natural Park in north-east Spain. Leaf gas exchange rates, chlorophyll fluorescence and shoot water potentials were measured once each season. Leaf nitrogen and carbon concentrations, leaf delta13C and delta15N and specific leaf area (SLA) were also measured once a year (August) on well developed mature leaves. Globularia alypum experienced seasonal fluctuations in their water potential, with the lowest values recorded in summer, whereas E. multiflora did not show significant differences in water potential among seasons. Moreover, lower water potentials were found in G. alypum than in E. multiflora throughout the entire study, suggesting that the latter behaved as a drought-avoiding species, whereas the former tolerated lower water potentials. In both species, maximum leaf gas exchange rates were observed in autumn and secondarily in spring; in contrast, photosynthetic and transpiration rates reached absolute minima in summer. The stronger fluctuations in water potential and leaf gas exchange rates found in G. alypum compared to E. multiflora, suggest that G. alypum is, sensu Levitt (1980), a water spender, whereas E. multiflora is a water conservative. This hypothesis is further supported by a higher integrated water-use efficiency (higher delta13C values) and a higher degree of sclerophylly (lower SLA) in E. multiflora in comparison with G. alypum. Globularia alypum showed higher leaf gas exchange rates and higher predawn potential photochemical efficiency (Fv/Fm) than E. multiflora during most of the study. In spring and autumn, predawn Fv/Fm values were within the optimal range, whereas chronic photoinhibition in summer and winter was detected in both species. However, whereas both species could maintain positive photosynthetic rates in winter, frequent negative values were found in summer, suggesting higher levels of stress during the drought period. These results together with the high correlations that were found between the net photosynthetic rates and several parameters of water availability (accumulated rainfall, soil moisture or midday water potential) provided further evidence of the key role of water availability in the regulation of the photosynthetic rates in these Mediterranean species. Warmer and drier conditions in future decades, as a consequence of climate change, may alter the present, slight competitive advantage of G. alypum and the fitness of both shrub species within semi-arid Mediterranean environments.
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Affiliation(s)
- Laura Llorens
- Unitat d'Ecofisiologia CSIC-CEAB-CREAF, CREAF, Edifici C, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
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Abstract
Chlorophyll fluorescence analysis has become one of the most powerful and widely used techniques available to plant physiologists and ecophysiologists. This review aims to provide an introduction for the novice into the methodology and applications of chlorophyll fluorescence. After a brief introduction into the theoretical background of the technique, the methodology and some of the technical pitfalls that can be encountered are explained. A selection of examples is then used to illustrate the types of information that fluorescence can provide.
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Affiliation(s)
- K Maxwell
- Department of Agricultural and Environmental Science, University Newcastle upon Tyne, UK
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