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Liu Y, Gong C, Pei W, Fan K, Shen W. Chlorophyll a fluorescence as a tool to monitor physiological status in the leaves of Artemisia ordosica under root cutting conditions. FRONTIERS IN PLANT SCIENCE 2024; 14:1308209. [PMID: 38288405 PMCID: PMC10824239 DOI: 10.3389/fpls.2023.1308209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 12/27/2023] [Indexed: 01/31/2024]
Abstract
Background Root cutting caused by underground coal mining subsidence is among the leading causes of plant damage in western China. Detection of root cutting stress is of great importance in evaluating the degree of plant damage and changes in physiological conditions in underground coal mining disturbance conditions. Methods The present study assessed the use of chlorophyll fluorescence OJIP transient data to evaluate the disturbance characteristics of root cutting stress on leaf photosynthetic mechanisms in the typical shrub Artemisia ordosica Krasch. Different root cutting ratios (10%, 20%, 30%, 50%, 75%, and 100%) were established on the roots of A. ordosica in the field, and the OJIP transient and JIP parameters of the leaves were measured. Results The overall OJIP curves and each OJIP step in leaves decreased as the root cutting ratio increased, but the impact was relatively small for root cutting ratios of less than 30%. Through the analysis of JIP parameters and the established energy pipeline model, it was found that the energy capture efficiency and electron transfer efficiency of photosystem II decreased as the root cutting ratio increased. Therefore, we also inferred that the threshold for the plant root cutting ratio at which leaf photosynthetic mechanisms begin to change is 30-50%. Conclusion These results indicate that OJIP transient analysis can serve as a non-destructive, rapid technique for detecting plant root cutting stress in coal mining subsidence areas, which is of great value for non-destructive monitoring of plant root damage.
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Affiliation(s)
- Ying Liu
- School of Earth and Environment, Anhui University of Science and Technology, Huainan, China
- The Anhui Province Engineering Laboratory of Water and Soil Resources Comprehensive Utilization and Ecological Protection in High Groundwater Mining Area, Anhui University of Science and Technology, Huainan, China
| | - Chuangang Gong
- School of Geodesy Geomatics, Anhui University of Science and Technology, Huainan, China
| | - Weihao Pei
- School of Earth and Environment, Anhui University of Science and Technology, Huainan, China
| | - Kaixuan Fan
- School of Earth and Environment, Anhui University of Science and Technology, Huainan, China
| | - Wenjing Shen
- School of Earth and Environment, Anhui University of Science and Technology, Huainan, China
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Drought Tolerance Assessment of Okra (Abelmoschus esculentus [L.] Moench) Accessions Based on Leaf Gas Exchange and Chlorophyll Fluorescence. Life (Basel) 2023; 13:life13030682. [PMID: 36983840 PMCID: PMC10052028 DOI: 10.3390/life13030682] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/27/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
Physiological and complementary phenotypic traits are essential in the selection of drought-adapted crop genotypes. Understanding the physiological response of diverse okra genotypes under drought stress conditions is critical to the selection of drought-tolerant accessions for production or breeding. The objective of this study was to assess the levels of drought tolerance in preliminarily selected okra accessions based on leaf gas exchange and chlorophyll fluorescence to determine best-performing genotypes for drought-tolerance breeding. Twenty-six genetically diverse okra accessions were screened under non-stressed (NS) and drought-stressed (DS) conditions under a controlled glasshouse environment using a 13 × 2 alpha lattice design in three replicates, in two growing seasons. Data were subjected to statistical analyses using various procedures. A significant genotype × water condition interaction effect was recorded for transpiration rate (T), net CO2 assimilation (A), intrinsic water use efficiency (WUEi), instantaneous water use efficiency (WUEins), minimum fluorescence (Fo′), maximum fluorescence (Fm′), maximum quantum efficiency of photosystem II photochemistry (Fv′/Fm′), the effective quantum efficiency of PSII photochemistry (ɸPSII), photochemical quenching (qP), nonphotochemical quenching (qN) and relative measure of electron transport to oxygen molecules (ETR/A). The results suggested variable drought tolerance of the studied okra accessions for selection. Seven principal components (PCs) contributing to 82% of the total variation for assessed physiological traits were identified under DS conditions. Leaf gas exchange parameters, T, A and WUEi, and chlorophyll fluorescence parameters such as the ɸPSII, Fv′/Fm′, qP, qN, ETR and ETR/A had high loading scores and correlated with WUEi, the ɸPSII, qP and ETR under DS conditions. The study found that optimal gas exchange and photoprotection enhance drought adaptation in the assessed okra genotypes and tested water regimes. Using the physiological variables, the study identified drought-tolerant accessions, namely LS05, LS06, LS07 and LS08 based on high A, T, Fm′, Fv′/Fm′ and ETR, and LS10, LS11, LS18 and LS23 based on high AES, Ci, Ci/Ca, WUEi, WUEins, ɸPSII and AES. The selected genotypes are high-yielding (≥5 g/plant) under drought stress conditions and will complement phenotypic data and guide breeding for water-limited agro-ecologies.
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Perera-Castro AV, Flexas J. The ratio of electron transport to assimilation (ETR/A N): underutilized but essential for assessing both equipment's proper performance and plant status. PLANTA 2023; 257:29. [PMID: 36592261 DOI: 10.1007/s00425-022-04063-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 12/27/2022] [Indexed: 06/17/2023]
Abstract
ETR/AN ratios should be in the range 7.5-10.5 for non-stressed C3 plants. Ratios extremely out of this range can be reflecting both uncontrolled plant status and technical mistakes during measurements. We urge users to explicitly refer to this ratio in future studies as a proof for internal data quality control. For the last few decades, the use of infra-red gas-exchange analysers (IRGAs) coupled with chlorophyll fluorometers that allow for measurements of net CO2 assimilation rate and estimates of electron transport rate over the same leaf area has been popularized. The evaluation of data from both instruments in an integrative manner can result in additional valuable information, such as the estimation of the light respiration, mesophyll conductance and the partitioning of the flux of electrons into carboxylation, oxygenation and alternative processes, among others. In this review, an additional and more 'straight' use of the combination of chlorophyll fluorescence and gas exchange-derived parameters is presented, namely using the direct ratio between two fully independently estimated parameters, electron transport rate (ETR)-determined by the fluorometer-and net CO2 assimilation rate (AN)-determined by the IRGA, i.e., the ETR/AN ratio, as a tool for fast detection of incongruencies in the data and potential technical problems associated with them, while checking for the study plant's status. To illustrate this application, a compilation of 75 studies that reported both parameters for a total of 178 species under varying physiological status is presented. Values of ETR/AN between 7.5 and 10.5 were most frequently found for non-stressed C3 plants. C4 species showed an average ETR/AN ratio of 4.7. The observed ratios were larger for species with high leaf mass per area and for plants subjected to stressful factors like drought or nutritional deficit. Knowing the expected ETR/AN ratio projects this ratio as a routinary and rapid check point for guaranteeing both the correct performance of equipment and the optimal/stress status of studied plants. All known errors associated with the under- or overestimation of ETR or AN are summarized in a checklist that aims to be routinely used by any IRGA/fluorometer user to strength the validity of their data.
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Affiliation(s)
- Alicia V Perera-Castro
- Department of Botany, Ecology and Plant Physiology, Universidad de La Laguna, Av. Astrofísico Francisco Sánchez, S/N, 38200, La Laguna, Canary Islands, Spain.
| | - Jaume Flexas
- Department of Biology, Agro-Environmental and Water Economics Institute (INAGEA), Universitat de LES Illes Balears, Carretera de Valldemossa Km 7.5, 07122, Palma, Illes Balears, Spain
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Acebron K, Salvatori N, Alberti G, Muller O, Peressotti A, Rascher U, Matsubara S. Elucidating the photosynthetic responses in chlorophyll-deficient soybean (Glycine max, L.) Cultivar. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY 2022. [DOI: 10.1016/j.jpap.2022.100152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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5
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Mandizvo T, Odindo AO, Mashilo J, Magwaza LS. Drought tolerance assessment of citron watermelon (Citrullus lanatus var. citroides (L.H. Bailey) Mansf. ex Greb.) accessions based on morphological and physiological traits. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 180:106-123. [PMID: 35405428 DOI: 10.1016/j.plaphy.2022.03.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/19/2022] [Accepted: 03/30/2022] [Indexed: 06/14/2023]
Abstract
Long-term cultivation of citron watermelon under water-constrained environments in sub-Saharan Africa resulted in the selection and domestication of highly tolerant genotypes. However, information on the magnitude of variation for drought tolerance in citron watermelon is limited for the effective selection of suitable genotypes for breeding. The objective of this study was to determine variation for drought tolerance among South African citron watermelon landrace accessions for selection and use as genetic stock for drought-tolerance breeding in this crop and closely-related cucurbit crops. Forty genetically differentiated citron watermelon accessions were grown under non-stress (NS) and drought-stress (DS) conditions under glasshouse environment. Data of physiological (i.e., leaf gas exchange and chlorophyll fluorescence parameters) and morphological traits (i.e., shoot and root system architecture traits, and fruit yield) were collected and subjected to various parametric statistical analyses. The accessions varied significantly for assessed traits under both NS and DS conditions which aided classification into five groups, namely; A (highly drought-tolerant), B (drought-tolerant), C (moderate drought-tolerant), D (drought-sensitive) and E (highly drought-sensitive). Drought-tolerant genotypes produced more fruit yield with less water compared with drought-sensitive genotypes. Several physiological and morphological parameters correlated with fruit yield under DS condition namely: instantaneous water-use efficiency (r = 0.97), leaf dry weight (r = 0.77), total root length (r = 0.46) and root dry weight (r = 0.48). The following accessions, namely: WWM-46, WWM-68, WWM-41(A), WWM-15, WWM-64, WWM-57, WWM-47, WWM-37(2), WWM-79, WWM-05 and WWM-50) were identified as highly drought-tolerant and recommended for drought-tolerance breeding in this crop or related cucurbit crops such as sweet dessert watermelon.
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Affiliation(s)
- Takudzwa Mandizvo
- Crop Science, School of Agricultural Earth and Environmental Sciences, University of KwaZulu-Natal, South Africa.
| | - Alfred Oduor Odindo
- Crop Science, School of Agricultural Earth and Environmental Sciences, University of KwaZulu-Natal, South Africa
| | - Jacob Mashilo
- Limpopo Department of Agriculture and Rural Development, Agriculture Regulatory and Technology Development, Directorate, Towoomba Research Centre, Private Bag X1615, Bela-Bela, 0480, South Africa
| | - Lembe Samukelo Magwaza
- Crop Science, School of Agricultural Earth and Environmental Sciences, University of KwaZulu-Natal, South Africa; Department of Horticultural Sciences, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
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Cousins AB, Mullendore DL, Sonawane BV. Recent developments in mesophyll conductance in C3, C4, and crassulacean acid metabolism plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 101:816-830. [PMID: 31960507 DOI: 10.1111/tpj.14664] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Accepted: 12/19/2019] [Indexed: 05/24/2023]
Abstract
The conductance of carbon dioxide (CO2 ) from the substomatal cavities to the initial sites of CO2 fixation (gm ) can significantly reduce the availability of CO2 for photosynthesis. There have been many recent reviews on: (i) the importance of gm for accurately modelling net rates of CO2 assimilation, (ii) on how leaf biochemical and anatomical factors influence gm , (iii) the technical limitation of estimating gm , which cannot be directly measured, and (iv) how gm responds to long- and short-term changes in growth and measurement environmental conditions. Therefore, this review will highlight these previous publications but will attempt not to repeat what has already been published. We will instead initially focus on the recent developments on the two-resistance model of gm that describe the potential of photorespiratory and respiratory CO2 released within the mitochondria to diffuse directly into both the chloroplast and the cytosol. Subsequently, we summarize recent developments in the three-dimensional (3-D) reaction-diffusion models and 3-D image analysis that are providing new insights into how the complex structure and organization of the leaf influences gm . Finally, because most of the reviews and literature on gm have traditionally focused on C3 plants we review in the final sections some of the recent developments, current understanding and measurement techniques of gm in C4 and crassulacean acid metabolism (CAM) plants. These plants have both specialized leaf anatomy and either a spatially or temporally separated CO2 concentrating mechanisms (C4 and CAM, respectively) that influence how we interpret and estimate gm compared with a C3 plants.
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Affiliation(s)
- Asaph B Cousins
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
| | - Daniel L Mullendore
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
| | - Balasaheb V Sonawane
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
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McClain AM, Sharkey TD. Building a better equation for electron transport estimated from Chl fluorescence: accounting for nonphotosynthetic light absorption. THE NEW PHYTOLOGIST 2020; 225:604-608. [PMID: 31605374 PMCID: PMC7660523 DOI: 10.1111/nph.16255] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 10/03/2019] [Indexed: 06/01/2023]
Affiliation(s)
- Alan M. McClain
- MSU-DOE Plant Research Laboratory, Michigan State University, 612 Wilson Rd, 210 Plant Biology Labs, East Lansing, MI 48824, USA
| | - Thomas D. Sharkey
- MSU-DOE Plant Research Laboratory, Michigan State University, 612 Wilson Rd, 210 Plant Biology Labs, East Lansing, MI 48824, USA
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Murakami K, Ibaraki Y. Time course of the photochemical reflectance index during photosynthetic induction: its relationship with the photochemical yield of photosystem II. PHYSIOLOGIA PLANTARUM 2019; 165:524-536. [PMID: 29660140 DOI: 10.1111/ppl.12745] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 04/08/2018] [Accepted: 04/09/2018] [Indexed: 05/11/2023]
Abstract
Time courses of photochemical reflectance index (PRI) of an attached cucumber leaf during a dark-light transition were compared with those of photochemical yields of photosystem II (YII ) to discuss the feasibility of PRI imaging for estimating the efficiency of photosynthetic light use. YII and PRI were simultaneously evaluated with a pulse-amplitude modulation chlorophyll fluorometer and a low-cost imaging system consisting of digital cameras and band-pass filters, respectively. YII decreased immediately after the transition and then increased under various photon flux densities. Although PRI exhibited delayed time courses with respect to YII under low light conditions, PRI decreased monotonically under high light conditions. There was no correlation between YII and the changes in PRI (ΔPRI) immediately after the transition but YII was correlated with ΔPRI under the steady-state photosynthesis. These results indicate that the use of PRI to estimate YII under fluctuating light based on the regression obtained at steady state can overestimate YII . The imaging system was also applied to evaluate the spatial PRI distribution within a leaf. While PRI of leaf areas that remained untreated, or had been treated with H2 O again, first dropped and then rose under low light and monotonically decreased under high light conditions, leaf areas treated with inhibitor (dichlorophenyl dimethylurea) did not exhibit any changes. It is likely that the inhibitor suppressed lumen acidification, which triggers a decrease in PRI. It was suggested that YII of leaves with malfunctions in the photosynthetic electron transport can be overestimated by the PRI-based estimation.
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Affiliation(s)
- Keach Murakami
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi 753-8515, Japan
| | - Yasuomi Ibaraki
- Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi 753-8515, Japan
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9
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Carriquí M, Douthe C, Molins A, Flexas J. Leaf anatomy does not explain apparent short-term responses of mesophyll conductance to light and CO 2 in tobacco. PHYSIOLOGIA PLANTARUM 2019; 165:604-618. [PMID: 29744895 DOI: 10.1111/ppl.12755] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 05/03/2018] [Accepted: 05/07/2018] [Indexed: 06/08/2023]
Abstract
Mesophyll conductance to CO2 (gm ), a key photosynthetic trait, is strongly constrained by leaf anatomy. Leaf anatomical parameters such as cell wall thickness and chloroplast area exposed to the mesophyll intercellular airspace have been demonstrated to determine gm in species with diverging phylogeny, leaf structure and ontogeny. However, the potential implication of leaf anatomy, especially chloroplast movement, on the short-term response of gm to rapid changes (i.e. seconds to minutes) under different environmental conditions (CO2 , light or temperature) has not been examined. The aim of this study was to determine whether the observed rapid variations of gm in response to variations of light and CO2 could be explained by changes in any leaf anatomical arrangements. When compared to high light and ambient CO2 , the values of gm estimated by chlorophyll fluorescence decreased under high CO2 and increased at low CO2 , while it decreased with decreasing light. Nevertheless, no changes in anatomical parameters, including chloroplast distribution, were found. Hence, the gm estimated by analytical models based on anatomical parameters was constant under varying light and CO2 . Considering this discrepancy between anatomy and chlorophyll fluorescence estimates, it is concluded that apparent fast gm variations should be due to artefacts in its estimation and/or to changes in the biochemical components acting on diffusional properties of the leaf (e.g. aquaporins and carbonic anhydrase).
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Affiliation(s)
- Marc Carriquí
- Research Group on Plant Biology Under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears - Instituto de investigaciones Agroambientales y de la Economía del Agua (INAGEA), Palma, 07122, Spain
| | - Cyril Douthe
- Research Group on Plant Biology Under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears - Instituto de investigaciones Agroambientales y de la Economía del Agua (INAGEA), Palma, 07122, Spain
| | - Arántzazu Molins
- Departament de Botànica, ICBIBE & Jardí Botànic, Facultat de Ciències Biològiques, Universitat de València, Valencia, 46100, Spain
| | - Jaume Flexas
- Research Group on Plant Biology Under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears - Instituto de investigaciones Agroambientales y de la Economía del Agua (INAGEA), Palma, 07122, Spain
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Atmospheric CO 2 captured by biogenic polyamines is transferred as a possible substrate to Rubisco for the carboxylation reaction. Sci Rep 2018; 8:17724. [PMID: 30531865 PMCID: PMC6286370 DOI: 10.1038/s41598-018-35641-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 10/22/2018] [Indexed: 11/17/2022] Open
Abstract
Biogenic polyamines are involved in a wide range of plant cellular processes, including cell division, morphogenesis and stress responses. However, the exact roles of biogenic polyamines are not well understood. We recently reported that biogenic polyamines that have multiple amino groups can react with CO2 and accelerate calcium carbonate formation in seawater. The ability of biogenic polyamines to capture atmospheric CO2 prompted us to examine their roles in photosynthesis. Here, we demonstrated that atmospheric CO2 captured by biogenic polyamines is a candidate substrate for the carboxylation reaction of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), which is an enzyme involved in the first major step of carbon fixation during photosynthesis, and that biogenic polyamines can accelerate the carboxylation reaction of this enzyme because of their specific affinity for CO2. Moreover, the results of our nuclear magnetic resonance (NMR) analysis showed that putrescine, which is the most common biogenic polyamine, reacts with atmospheric CO2 and promotes the formation of carbamate derivatives and bicarbonate in aqueous environments. A sufficient amount of CO2 is well known to be produced by carbonic anhydrase from bicarbonate in vivo. The present study indicates that CO2 would be also produced by the equilibrium reaction from carbonate produced by biogenic polyamines and would be used as a substrate of Rubisco, too. Our results may suggest a new photosynthetic research strategy that involves CO2-concentrating mechanisms and also possibly constitutes a potential tool for reducing atmospheric CO2 levels and, consequently, global warming.
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Zhang MM, Fan DY, Sun GY, Chow WS. Optimising the linear electron transport rate measured by chlorophyll a fluorescence to empirically match the gross rate of oxygen evolution in white light: towards improved estimation of the cyclic electron flux around photosystem I in leaves. FUNCTIONAL PLANT BIOLOGY : FPB 2018; 45:1138-1148. [PMID: 32290975 DOI: 10.1071/fp18039] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 05/25/2018] [Indexed: 06/11/2023]
Abstract
The cyclic electron flux (CEF) around photosystem I (PSI) was discovered in isolated chloroplasts more than six decades ago, but its quantification has been hampered by the absence of net formation of a product or net consumption of a substrate. We estimated in vivo CEF in leaves as the difference (ΔFlux) between the total electron flux through PSI (ETR1) measured by a near infrared signal, and the linear electron flux through both photosystems by optimised measurement of chlorophyll a fluorescence (LEFfl). Chlorophyll fluorescence was excited by modulated green light from a light-emitting diode at an optimal average irradiance, and the fluorescence was detected at wavelengths >710nm. In this way, LEFfl matched the gross rate of oxygen evolution multiplied by 4 (LEFO2) in broad-spectrum white actinic irradiance up to half (spinach, poplar and rice) or one third (cotton) of full sunlight irradiance. This technique of estimating CEF can be applied to leaves attached to a plant.
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Affiliation(s)
- Meng-Meng Zhang
- College of Life Science, Northeast Forestry University, Harbin, Heilongjiang, 150040, China
| | - Da-Yong Fan
- Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Guang-Yu Sun
- College of Life Science, Northeast Forestry University, Harbin, Heilongjiang, 150040, China
| | - Wah Soon Chow
- Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
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Chartrand KM, Szabó M, Sinutok S, Rasheed MA, Ralph PJ. Living at the margins - The response of deep-water seagrasses to light and temperature renders them susceptible to acute impacts. MARINE ENVIRONMENTAL RESEARCH 2018; 136:126-138. [PMID: 29503105 DOI: 10.1016/j.marenvres.2018.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 02/05/2018] [Accepted: 02/08/2018] [Indexed: 06/08/2023]
Abstract
Seagrasses inhabit environments where light varies at different timescales, nonetheless are acutely sensitive to reductions in light beyond some conditional bounds. Two tropical deep-water seagrasses, Halophila decipiens and Halophila spinulosa, from the Great Barrier Reef were tested for their response to defined light and temperature regimes to identify their growth requirements and potential thresholds of mortality. Species were exposed to two light intensities, saturating (75 μmol photons m-2 s-1) and limiting (25 μmol photons m-2 s-1) light and two temperature treatments (26 °C and 30 °C) over a four-week period. Wavelength-specific parameters of PSII photochemistry were evaluated for seagrass leaves, as well as shoot density, gas exchange, and pigment content. Both species were sustained under saturating light levels (3.2 mol photons m-2 d-1) while limiting light led to decreased shoot density for H. decipiens and H. spinulosa after two and four weeks, respectively. Wavelength-specific photochemistry was also affected under light-limiting treatments for both species while the functional absorption cross section was highly conserved. Photoacclimation and physiological adjustments by either species was not adequate to compensate for reduced irradiance suggesting these plants reside at the margins of their functional limits. As such, relatively short periods of light attenuating events, like dredging or flood plumes, may be detrimental to deep-water seagrass populations.
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Affiliation(s)
- Kathryn M Chartrand
- Centre for Tropical Water & Aquatic Ecosystem Research, James Cook University, Cairns, Queensland, Australia; Climate Change Cluster, University of Technology Sydney, Broadway, New South Wales, Australia.
| | - Milán Szabó
- Climate Change Cluster, University of Technology Sydney, Broadway, New South Wales, Australia; Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Sutinee Sinutok
- Climate Change Cluster, University of Technology Sydney, Broadway, New South Wales, Australia; Faculty of Environmental Management, Prince of Songkla University, Hat Yai, Thailand; Coastal Oceanography and Climate Change Research Center, Prince of Songkla University, Hat Yai, Thailand
| | - Michael A Rasheed
- Centre for Tropical Water & Aquatic Ecosystem Research, James Cook University, Cairns, Queensland, Australia
| | - Peter J Ralph
- Climate Change Cluster, University of Technology Sydney, Broadway, New South Wales, Australia
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Murakami K, Matsuda R, Fujiwara K. Quantification of excitation energy distribution between photosystems based on a mechanistic model of photosynthetic electron transport. PLANT, CELL & ENVIRONMENT 2018; 41:148-159. [PMID: 28548208 DOI: 10.1111/pce.12986] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 04/16/2017] [Accepted: 04/25/2017] [Indexed: 06/07/2023]
Abstract
Absorbed light energy is converted into excitation energy. The excitation energy is distributed to photosystems depending on the wavelength and drives photochemical reactions. A non-destructive, mechanistic and quantitative method for estimating the fraction of the excitation energy distributed to photosystem II (f) was developed. For the f values for two simultaneously provided actinic lights (ALs) with different spectral distributions to be estimated, photochemical yields of the photosystems were measured under the ALs and were then fitted to an electron transport model assuming the balance between the electron transport rates through the photosystems. For the method to be tested using leaves with different properties in terms of the long-term and short-term acclimation (adjustment of photosystem stoichiometry and state transition, respectively), the f values for red and far-red light (R and FR) were estimated in leaves grown (~1 week) under white light without and with supplemental FR and adapted (~10 min) to R without and with supplemental FR. The f values for R were clearly greater than those for FR and those of leaves grown with and adapted to supplemental FR tended to be higher than the controls. These results are consistent with previous studies and therefore support the validity of the proposed method.
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Affiliation(s)
- Keach Murakami
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657, Japan
| | - Ryo Matsuda
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657, Japan
| | - Kazuhiro Fujiwara
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo, 113-8657, Japan
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Flexas J, Cano FJ, Carriquí M, Coopman RE, Mizokami Y, Tholen D, Xiong D. CO2 Diffusion Inside Photosynthetic Organs. THE LEAF: A PLATFORM FOR PERFORMING PHOTOSYNTHESIS 2018. [DOI: 10.1007/978-3-319-93594-2_7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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15
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van der Putten PEL, Yin X, Struik PC. Calibration matters: On the procedure of using the chlorophyll fluorescence method to estimate mesophyll conductance. JOURNAL OF PLANT PHYSIOLOGY 2018; 220:167-172. [PMID: 29190520 DOI: 10.1016/j.jplph.2017.11.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 11/17/2017] [Accepted: 11/20/2017] [Indexed: 06/07/2023]
Abstract
Estimates of mesophyll conductance (gm), when calculated from chlorophyll fluorescence, are uncertain, especially when the photosystem II (PSII) operating efficiency is measured from the traditional single saturation pulse methodology. The multiphase flash method has recently been recommended to replace the single saturation pulse method, allowing a more reliable estimation of gm. Also, many researchers still directly use the PSII operating efficiency to derive linear electron transport rate J (that is required to estimate gm), without appropriate calibration using measurements under non-photorespiratory conditions. Here we demonstrate for tomato and rice that (i) using the multiphase flash method did not yield realistic estimates of gm if no calibration was conducted; and (ii) using the single saturation pulse method still gave reasonable estimates of gm when calibration based on the non-photorespiratory measurements was properly conducted. Therefore, conducting calibration based on data under non-photorespiratory conditions was indispensable for a reliable estimation of gm, regardless whether the multiphase flash or the single saturation pulse method was used for measuring the PSII operating efficiency. Other issues related to the procedure of using the chlorophyll fluorescence method to estimate gm were discussed.
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Affiliation(s)
- Peter E L van der Putten
- Centre for Crop Systems Analysis, Department of Plant Sciences, Wageningen University & Research, P.O. Box 430, 6700 AK, Wageningen, The Netherlands
| | - Xinyou Yin
- Centre for Crop Systems Analysis, Department of Plant Sciences, Wageningen University & Research, P.O. Box 430, 6700 AK, Wageningen, The Netherlands.
| | - Paul C Struik
- Centre for Crop Systems Analysis, Department of Plant Sciences, Wageningen University & Research, P.O. Box 430, 6700 AK, Wageningen, The Netherlands
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16
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Xiao Y, Zhu XG. Components of mesophyll resistance and their environmental responses: A theoretical modelling analysis. PLANT, CELL & ENVIRONMENT 2017; 40:2729-2742. [PMID: 28743156 DOI: 10.1111/pce.13040] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 07/12/2017] [Accepted: 07/14/2017] [Indexed: 05/12/2023]
Abstract
Mesophyll resistance (rm ), stomatal resistance, and biochemical limitations are recognized as three critical factors limiting leaf photosynthesis. Contrary to the expectation of being a constant, rm not only varies with light and CO2 conditions but also shows different responses among species. To elucidate the mechanistic basis of these responses, we derived an analytical model of rm , which incorporates various anatomical and biochemical factors including permeabilities of cell wall and chloroplast envelope to CO2 and HCO3- , carbonic anhydrase activities in cytosol and stroma, Rubisco activities, and relative location of mitochondria and chloroplast. The robustness of this model was confirmed by comparing the predicted rm and its components to numerical models developed at cell and leaf levels, which incorporate detailed 3-dimensional cell and leaf anatomies, CO2 hydration and diffusion processes from intercellular air space to stroma, and CO2 fixation by Rubisco. A combination of these model analyses shows that the varying rm is influenced by four biochemical factors: (a) nonuniform photosynthesis status across the leaf, (b) photorespiration and respiration, (c) bicarbonate leakage on the chloroplast envelope, and (d) hydration activity in cytosol and stroma. This study provides a theoretical framework to study components of rm and their responses to environmental perturbations.
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Affiliation(s)
- Yi Xiao
- Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xin-Guang Zhu
- Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Changsha, China
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17
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Evans JR, Morgan PB, von Caemmerer S. Light Quality Affects Chloroplast Electron Transport Rates Estimated from Chl Fluorescence Measurements. PLANT & CELL PHYSIOLOGY 2017; 58:1652-1660. [PMID: 29016964 DOI: 10.1093/pcp/pcx103] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 07/09/2017] [Indexed: 05/23/2023]
Abstract
Chl fluorescence has been used widely to calculate photosynthetic electron transport rates. Portable photosynthesis instruments allow for combined measurements of gas exchange and Chl fluorescence. We analyzed the influence of spectral quality of actinic light on Chl fluorescence and the calculated electron transport rate, and compared this with photosynthetic rates measured by gas exchange in the absence of photorespiration. In blue actinic light, the electron transport rate calculated from Chl fluorescence overestimated the true rate by nearly a factor of two, whereas there was closer agreement under red light. This was consistent with the prediction made with a multilayer leaf model using profiles of light absorption and photosynthetic capacity. Caution is needed when interpreting combined measurements of Chl fluorescence and gas exchange, such as the calculation of CO2 partial pressure in leaf chloroplasts.
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Affiliation(s)
- John R Evans
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Patrick B Morgan
- LI-COR Inc., Lincoln, NE 68504, USA
- School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE 68504, USA
| | - Susanne von Caemmerer
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
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18
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Théroux-Rancourt G, Gilbert ME. The light response of mesophyll conductance is controlled by structure across leaf profiles. PLANT, CELL & ENVIRONMENT 2017; 40:726-740. [PMID: 28039917 DOI: 10.1111/pce.12890] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 12/19/2016] [Accepted: 12/21/2016] [Indexed: 05/05/2023]
Abstract
Mesophyll conductance to CO2 (gm ) may respond to light either through regulated dynamic mechanisms or due to anatomical and structural factors. At low light, some layers of cells in the leaf cross-section approach photocompensation and contribute minimally to bulk leaf photosynthesis and little to whole leaf gm (gm,leaf ). Thus, the bulk gm,leaf will appear to respond to light despite being based upon cells having an anatomically fixed mesophyll conductance. Such behaviour was observed in species with contrasting leaf structure using the variable J or stable isotope method of measuring gm,leaf . A species with bifacial structure, Arbutus × 'Marina', and an isobilateral species, Triticum durum L., had contrasting responses of gm,leaf upon varying adaxial or abaxial illumination. Anatomical observations, when coupled with the proposed model of gm,leaf to photosynthetic photon flux density (PPFD) response, successfully represented the observed gas exchange data. The theoretical and observed evidence that gm,leaf apparently responds to light has large implications for how gm,leaf values are interpreted, particularly limitation analyses, and indicates the importance of measuring gm under full light saturation. Responses of gm,leaf to the environment should be treated as an emergent property of a distributed 3D structure, and not solely a leaf area-based phenomenon.
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Affiliation(s)
| | - Matthew E Gilbert
- Department of Plant Sciences, University of California, Davis, 95616, USA
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19
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Bellasio C, Beerling DJ, Griffiths H. An Excel tool for deriving key photosynthetic parameters from combined gas exchange and chlorophyll fluorescence: theory and practice. PLANT, CELL & ENVIRONMENT 2016; 39:1180-97. [PMID: 25923517 DOI: 10.1111/pce.12560] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/10/2015] [Accepted: 02/25/2015] [Indexed: 05/23/2023]
Abstract
Combined photosynthetic gas exchange and modulated fluorometres are widely used to evaluate physiological characteristics associated with phenotypic and genotypic variation, whether in response to genetic manipulation or resource limitation in natural vegetation or crops. After describing relatively simple experimental procedures, we present the theoretical background to the derivation of photosynthetic parameters, and provide a freely available Excel-based fitting tool (EFT) that will be of use to specialists and non-specialists alike. We use data acquired in concurrent variable fluorescence-gas exchange experiments, where A/Ci and light-response curves have been measured under ambient and low oxygen. From these data, the EFT derives light respiration, initial PSII (photosystem II) photochemical yield, initial quantum yield for CO2 fixation, fraction of incident light harvested by PSII, initial quantum yield for electron transport, electron transport rate, rate of photorespiration, stomatal limitation, Rubisco (ribulose 1·5-bisphosphate carboxylase/oxygenase) rate of carboxylation and oxygenation, Rubisco specificity factor, mesophyll conductance to CO2 diffusion, light and CO2 compensation point, Rubisco apparent Michaelis-Menten constant, and Rubisco CO2 -saturated carboxylation rate. As an example, a complete analysis of gas exchange data on tobacco plants is provided. We also discuss potential measurement problems and pitfalls, and suggest how such empirical data could subsequently be used to parameterize predictive photosynthetic models.
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Affiliation(s)
- Chandra Bellasio
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - David J Beerling
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
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20
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Bellasio C, Beerling DJ, Griffiths H. Deriving C4 photosynthetic parameters from combined gas exchange and chlorophyll fluorescence using an Excel tool: theory and practice. PLANT, CELL & ENVIRONMENT 2016; 39:1164-79. [PMID: 26286697 DOI: 10.1111/pce.12626] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 08/06/2015] [Indexed: 05/27/2023]
Abstract
The higher photosynthetic potential of C4 plants has led to extensive research over the past 50 years, including C4 -dominated natural biomes, crops such as maize, or for evaluating the transfer of C4 traits into C3 lineages. Photosynthetic gas exchange can be measured in air or in a 2% Oxygen mixture using readily available commercial gas exchange and modulated PSII fluorescence systems. Interpretation of these data, however, requires an understanding (or the development) of various modelling approaches, which limit the use by non-specialists. In this paper we present an accessible summary of the theory behind the analysis and derivation of C4 photosynthetic parameters, and provide a freely available Excel Fitting Tool (EFT), making rigorous C4 data analysis accessible to a broader audience. Outputs include those defining C4 photochemical and biochemical efficiency, the rate of photorespiration, bundle sheath conductance to CO2 diffusion and the in vivo biochemical constants for PEP carboxylase. The EFT compares several methodological variants proposed by different investigators, allowing users to choose the level of complexity required to interpret data. We provide a complete analysis of gas exchange data on maize (as a model C4 organism and key global crop) to illustrate the approaches, their analysis and interpretation. © 2015 John Wiley & Sons Ltd.
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Affiliation(s)
- Chandra Bellasio
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - David J Beerling
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
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21
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Iermak I, Vink J, Bader AN, Wientjes E, van Amerongen H. Visualizing heterogeneity of photosynthetic properties of plant leaves with two-photon fluorescence lifetime imaging microscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1473-1478. [PMID: 27239747 DOI: 10.1016/j.bbabio.2016.05.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 05/09/2016] [Accepted: 05/21/2016] [Indexed: 01/09/2023]
Abstract
Two-photon fluorescence lifetime imaging microscopy (FLIM) was used to analyse the distribution and properties of Photosystem I (PSI) and Photosystem II (PSII) in palisade and spongy chloroplasts of leaves from the C3 plant Arabidopsis thaliana and the C4 plant Miscanthus x giganteus. This was achieved by separating the time-resolved fluorescence of PSI and PSII in the leaf. It is found that the PSII antenna size is larger on the abaxial side of A. thaliana leaves, presumably because chloroplasts in the spongy mesophyll are "shaded" by the palisade cells. The number of chlorophylls in PSI on the adaxial side of the A. thaliana leaf is slightly higher. The C4 plant M. x giganteus contains both mesophyll and bundle sheath cells, which have a different PSI/PSII ratio. It is shown that the time-resolved fluorescence of bundle sheath and mesophyll cells can be analysed separately. The relative number of chlorophylls, which belong to PSI (as compared to PSII) in the bundle sheath cells is at least 2.5 times higher than in mesophyll cells. FLIM is thus demonstrated to be a useful technique to study the PSI/PSII ratio and PSII antenna size in well-defined regions of plant leaves without having to isolate pigment-protein complexes.
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Affiliation(s)
- Ievgeniia Iermak
- Laboratory of Biophysics, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands; BioSolar Cells Project Office, P.O. Box 98, 6700 AB Wageningen, The Netherlands
| | - Jochem Vink
- Laboratory of Biophysics, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands
| | - Arjen N Bader
- Laboratory of Biophysics, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands; MicroSpectroscopy Centre, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands
| | - Emilie Wientjes
- Laboratory of Biophysics, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands
| | - Herbert van Amerongen
- Laboratory of Biophysics, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands; BioSolar Cells Project Office, P.O. Box 98, 6700 AB Wageningen, The Netherlands; MicroSpectroscopy Centre, Wageningen University, P.O. Box 8128, 6700 ET Wageningen, The Netherlands
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22
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Barbour MM, Bachmann S, Bansal U, Bariana H, Sharp P. Genetic control of mesophyll conductance in common wheat. THE NEW PHYTOLOGIST 2016; 209:461-5. [PMID: 26763680 DOI: 10.1111/nph.13628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Affiliation(s)
- Margaret M Barbour
- Center for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Road, Brownlow Hill, NSW, 2570, Australia
| | - Sarah Bachmann
- Center for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Road, Brownlow Hill, NSW, 2570, Australia
| | - Urmil Bansal
- Faculty of Agriculture and Environment, Plant Breeding Institute, The University of Sydney, PMB4011, Narellan, NSW, 2567, Australia
| | - Harbans Bariana
- Faculty of Agriculture and Environment, Plant Breeding Institute, The University of Sydney, PMB4011, Narellan, NSW, 2567, Australia
| | - Peter Sharp
- Faculty of Agriculture and Environment, Plant Breeding Institute, The University of Sydney, PMB4011, Narellan, NSW, 2567, Australia
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23
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Verboven P, Herremans E, Helfen L, Ho QT, Abera M, Baumbach T, Wevers M, Nicolaï BM. Synchrotron X-ray computed laminography of the three-dimensional anatomy of tomato leaves. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 81:169-82. [PMID: 25319143 DOI: 10.1111/tpj.12701] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 10/01/2014] [Accepted: 10/10/2014] [Indexed: 05/23/2023]
Abstract
Synchrotron radiation computed laminography (SR-CL) is presented as an imaging method for analyzing the three-dimensional (3D) anatomy of leaves. The SR-CL method was used to provide 3D images of 1-mm² samples of intact leaves at a pixel resolution of 750 nm. The method allowed visualization and quantitative analysis of palisade and spongy mesophyll cells, and showed local venation patterns, aspects of xylem vascular structure and stomata. The method failed to image subcellular organelles such as chloroplasts. We constructed 3D computer models of leaves that can provide a basis for calculating gas exchange, light penetration and water and solute transport. The leaf anatomy of two different tomato genotypes grown in saturating light conditions was compared by 3D analysis. Differences were found in calculated values of tissue porosity, cell number density, cell area to volume ratio and cell volume and cell shape distributions of palisade and spongy cell layers. In contrast, the exposed cell area to leaf area ratio in mesophyll, a descriptor that correlates to the maximum rate of photosynthesis in saturated light conditions, was no different between spongy and palisade cells or between genotypes. The use of 3D image processing avoids many of the limitations of anatomical analysis with two-dimensional sections.
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Affiliation(s)
- Pieter Verboven
- Division BIOSYST-MeBioS, Katholieke Universiteit Leuven, B-3001, Leuven, Belgium
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24
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Klughammer C, Schreiber U. Apparent PS II absorption cross-section and estimation of mean PAR in optically thin and dense suspensions of Chlorella. PHOTOSYNTHESIS RESEARCH 2015; 123:77-92. [PMID: 25218266 DOI: 10.1007/s11120-014-0040-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Accepted: 09/03/2014] [Indexed: 05/12/2023]
Abstract
Theoretical prediction of effective mean PAR in optically dense samples is complicated by various optical effects, including light scattering and reflections. Direct information on the mean rate of photon absorption by PS II is provided by the kinetics of the fluorescence rise induced upon onset of strong actinic illumination (O-I1 rise). A recently introduced kinetic multi-color PAM fluorometer was applied to study the relationship between initial slope and cell density in the relatively simple model system of suspensions of Chlorella. Use of a curve fitting routine was made which was originally developed for assessment of the wavelength-dependent absorption cross-section of PS II, σ II(λ), in dilute suspensions. The model underlying analysis of the O-I1 rise kinetics is outlined and data on the relationship between fitted values of σ II(λ) and PAR in dilute samples are presented. With increasing cell density, lowering of apparent cross-section, <σ>(λ), with respect to σ II(λ), relates to a decrease of effective mean PAR, <PAR>(λ), relative to incident PAR(λ). When ML and AL are applied in the same direction, the decline of <σ>(λ)/σ II(λ) with increasing optical density is less steep than that of the theoretically predicted <PAR>(λ)/PAR(λ). It approaches a value of 0.5 when the same colors of ML and AL are used, in agreement with theory. These observations open the way for estimating mean PAR in optically dense samples via measurements of <σ>(λ)/σ II(λ)).
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Affiliation(s)
- Christof Klughammer
- Julius-von-Sachs Institut für Biowissenschaften, Universität Würzburg, Julius-von-Sachs Platz 2, 97082, Würzburg, Germany
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25
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Igamberdiev AU. Control of Rubisco function via homeostatic equilibration of CO2 supply. FRONTIERS IN PLANT SCIENCE 2015; 6:106. [PMID: 25767475 PMCID: PMC4341507 DOI: 10.3389/fpls.2015.00106] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 02/09/2015] [Indexed: 05/09/2023]
Abstract
Rubisco is the most abundant protein on Earth that serves as the primary engine of carbon assimilation. It is characterized by a slow rate and low specificity for CO2 leading to photorespiration. We analyze here the challenges of operation of this enzyme as the main carbon fixation engine. The high concentration of Rubisco exceeds that of its substrate CO2 by 2-3 orders of magnitude; however, the total pool of available carbon in chloroplast, i.e., mainly bicarbonate, is comparable to the concentration of Rubisco active sites. This makes the reactant stationary assumption (RSA), which is essential as a condition of satisfying the Michaelis-Menten (MM) kinetics, valid if we assume that the delivery of CO2 from this pool is not limiting. The RSA is supported by active carbonic anhydrases (CA) that quickly equilibrate bicarbonate and CO2 pools and supply CO2 to Rubisco. While the operation of stromal CA is independent of light reactions, the thylakoidal CA associated with PSII and pumping CO2 from the thylakoid lumen is coordinated with the rate of electron transport, water splitting and proton gradient across the thylakoid membrane. At high CO2 concentrations, CA becomes less efficient (the equilibrium becomes unfavorable), so a deviation from the MM kinetics is observed, consistent with Rubisco reaching its Vmax at approximately 50% lower level than expected from the classical MM curve. Previously, this deviation was controversially explained by the limitation of RuBP regeneration. At low ambient CO2 and correspondingly limited capacity of the bicarbonate pool, its depletion at Rubisco sites is relieved in that the enzyme utilizes O2 instead of CO2, i.e., by photorespiration. In this process, CO2 is supplied back to Rubisco, and the chloroplastic redox state and energy level are maintained. It is concluded that the optimal performance of photosynthesis is achieved via the provision of continuous CO2 supply to Rubisco by carbonic anhydrases and photorespiration.
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Affiliation(s)
- Abir U. Igamberdiev
- *Correspondence: Abir U. Igamberdiev, Department of Biology, Memorial University of Newfoundland, 232 Elizabeth Avenue, St. John’s, NL A1B 3X9, Canada
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26
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Szabó M, Wangpraseurt D, Tamburic B, Larkum AWD, Schreiber U, Suggett DJ, Kühl M, Ralph PJ. Effective light absorption and absolute electron transport rates in the coral Pocillopora damicornis. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2014; 83:159-167. [PMID: 25146689 DOI: 10.1016/j.plaphy.2014.07.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2014] [Accepted: 07/20/2014] [Indexed: 06/03/2023]
Abstract
Pulse Amplitude Modulation (PAM) fluorometry has been widely used to estimate the relative photosynthetic efficiency of corals. However, both the optical properties of intact corals as well as past technical constrains to PAM fluorometers have prevented calculations of the electron turnover rate of PSII. We used a new Multi-colour PAM (MC-PAM) in parallel with light microsensors to determine for the first time the wavelength-specific effective absorption cross-section of PSII photochemistry, σII(λ), and thus PAM-based absolute electron transport rates of the coral photosymbiont Symbiodinium both in culture and in hospite in the coral Pocillopora damicornis. In both cases, σII of Symbiodinium was highest in the blue spectral region and showed a progressive decrease towards red wavelengths. Absolute values for σII at 440 nm were up to 1.5-times higher in culture than in hospite. Scalar irradiance within the living coral tissue was reduced by 20% in the blue when compared to the incident downwelling irradiance. Absolute electron transport rates of P. damicornis at 440 nm revealed a maximum PSII turnover rate of ca. 250 electrons PSII(-1) s(-1), consistent with one PSII turnover for every 4 photons absorbed by PSII; this likely reflects the limiting steps in electron transfer between PSII and PSI. Our results show that optical properties of the coral host strongly affect light use efficiency of Symbiodinium. Therefore, relative electron transport rates do not reflect the productivity rates (or indeed how the photosynthesis-light response is parameterised). Here we provide a non-invasive approach to estimate absolute electron transport rates in corals.
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Affiliation(s)
- Milán Szabó
- Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, Broadway 2007, NSW, Australia.
| | - Daniel Wangpraseurt
- Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, Broadway 2007, NSW, Australia
| | - Bojan Tamburic
- Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, Broadway 2007, NSW, Australia
| | - Anthony W D Larkum
- Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, Broadway 2007, NSW, Australia
| | - Ulrich Schreiber
- Julius-von-Sachs Institut für Biowissenschaften, Lehrstuhl Botanik I, Universität Würzburg, Germany
| | - David J Suggett
- Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, Broadway 2007, NSW, Australia
| | - Michael Kühl
- Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, Broadway 2007, NSW, Australia; Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000 Helsingør, Denmark
| | - Peter J Ralph
- Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, Broadway 2007, NSW, Australia
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27
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Gu L, Sun Y. Artefactual responses of mesophyll conductance to CO2 and irradiance estimated with the variable J and online isotope discrimination methods. PLANT, CELL & ENVIRONMENT 2014; 37:1231-49. [PMID: 24237289 DOI: 10.1111/pce.12232] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 10/31/2013] [Accepted: 11/03/2013] [Indexed: 05/04/2023]
Abstract
Studies with the variable J method have reported that mesophyll conductance (gm ) rapidly decreases with increasing intercellular CO2 partial pressures (Ci ) or decreasing irradiance. Similar responses have been suggested with the online isotope discrimination method, although with less consistency. Here we show that even when the true gm is constant, the variable J method can produce an artefactual dependence of gm on Ci or irradiance similar to those reported in previous studies for any of the following factors: day respiration and chloroplastic CO2 photocompensation point are estimated with Laisk method; Ci or electron transport rate is positively biased; net photosynthetic rate is negatively biased; insufficient NADPH is assumed while insufficient ATP limits RuBP regeneration. The isotopic method produces similar artefacts if fractionation of carboxylation or Ci is positively biased or Δ(13) negatively biased. A non-zero chloroplastic resistance to CO2 movement results in a qualitatively different dependence of gm on Ci or irradiance and this dependence is only sensitive at low Ci . We thus cannot rule out the possibility that previously reported dependence of gm on Ci or irradiance is a methodological artefact. Recommendations are made to take advantage of sensitivities of the variable J and isotopic methods for estimating gm .
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Affiliation(s)
- Lianhong Gu
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
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28
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Buckley TN, Warren CR. The role of mesophyll conductance in the economics of nitrogen and water use in photosynthesis. PHOTOSYNTHESIS RESEARCH 2014; 119:77-88. [PMID: 23609621 DOI: 10.1007/s11120-013-9825-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 04/08/2013] [Indexed: 06/02/2023]
Abstract
A recent resurgence of interest in formal optimisation theory has begun to improve our understanding of how variations in stomatal conductance and photosynthetic capacity control the response of whole plant photosynthesis and growth to the environment. However, mesophyll conductance exhibits similar variation and has similar impact on photosynthesis as stomatal conductance; yet, the role of mesophyll conductance in the economics of photosynthetic resource use has not been thoroughly explored. In this article, we first briefly summarise the knowledge of how mesophyll conductance varies in relation to environmental factors that also affect stomatal conductance and photosynthetic capacity, and then we use a simple analytical approach to begin to explore how these important controls on photosynthesis should mutually co-vary in a plant canopy in the optimum. Our analysis predicts that when either stomatal or mesophyll conductance is limited by fundamental biophysical constraints in some areas of a canopy, e.g. reduced stomatal conductance in upper canopy leaves due to reduced water potential, the other of the two conductances should increase in those leaves, while photosynthetic capacity should decrease. Our analysis also predicts that if mesophyll conductance depends on nitrogen investment in one or more proteins, then nitrogen investment should shift away from Rubisco and towards mesophyll conductance if hydraulic or other constraints cause chloroplastic CO2 concentration to decline. Thorough exploration of these issues awaits better knowledge of whether and how mesophyll conductance is itself limited by nitrogen investment, and about how these determinants of photosynthetic CO2 supply and demand co-vary among leaves in real plant canopies.
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Affiliation(s)
- Thomas N Buckley
- Department of Biology, Sonoma State University, Rohnert Park, CA, 94928, USA,
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Martins SC, Galmés J, Molins A, DaMatta FM. Improving the estimation of mesophyll conductance to CO₂: on the role of electron transport rate correction and respiration. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:3285-98. [PMID: 23833194 PMCID: PMC3733151 DOI: 10.1093/jxb/ert168] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Mesophyll conductance (gm) can markedly limit photosynthetic CO₂ assimilation and is required to estimate the parameters of the Farquhar-von Caemmerer-Berry (FvCB) model properly. The variable J (electron transport rate) is the most frequently used method for estimating gm, and the correct determination of J is one of its requirements. Recent evidence has shown that calibrating J can lead to some errors in estimating gm, but to what extent the parameterization of the FvCB model is affected by calibrations is not well known. In addition to determining the FvCB parameters, variants of the J calibration method were tested to address whether varying CO₂ or light levels, possible alternative electron sinks, or contrasting leaf structural properties might play a role in determining differences in αβ, the product of the leaf absorptance (α) and the photosystem II optical cross-section (β). It was shown that differences in αβ were mainly attributed to the use of A/C(i) or A/PPFD curves to calibrate J. The different αβ values greatly influenced g(m), leading to a high number of unrealistic values in addition to affecting the estimates of the FvCB model parameters. A new approach was devised to retrieve leaf respiration in the light from combined A/C(i) and A/C(c) curves and a framework to understand the high variation in observed gm values. Overall, a background is provided to decrease the noise in gm, facilitating data reporting and allowing better retrieval of the information presented in A/C(i) and A/C(c) curves.
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Affiliation(s)
- Samuel C.V. Martins
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-000 Viçosa, MG, Brazil
| | - Jeroni Galmés
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears, Ctra. de Valldemossa, km 7.5, 07071, Palma, Balearic Islands, Spain
| | - Arántzazu Molins
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears, Ctra. de Valldemossa, km 7.5, 07071, Palma, Balearic Islands, Spain
| | - Fábio M. DaMatta
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-000 Viçosa, MG, Brazil
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30
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Ye ZP, Suggett DJ, Robakowski P, Kang HJ. A mechanistic model for the photosynthesis-light response based on the photosynthetic electron transport of photosystem II in C3 and C4 species. THE NEW PHYTOLOGIST 2013; 199:110-120. [PMID: 23521402 DOI: 10.1111/nph.12242] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 02/21/2013] [Indexed: 06/01/2023]
Abstract
A new mechanistic model of the photosynthesis-light response is developed based on photosynthetic electron transport via photosystem II (PSII) to specifically describe light-harvesting characteristics and associated biophysical parameters of photosynthetic pigment molecules. This model parameterizes 'core' characteristics not only of the light response but also of difficult to measure physical parameters of photosynthetic pigment molecules in plants. Application of the model to two C3 and two C4 species grown under the same conditions demonstrated that the model reproduced extremely well (r(2) > 0.992) the light response trends of both electron transport and CO2 uptake. In all cases, the effective absorption cross-section of photosynthetic pigment molecules decreased with increasing light intensity, demonstrating novel operation of a key mechanism for plants to avoid high light damage. In parameterizing these previously difficult to measure characteristics of light harvesting in higher plants, the model provides a new means to understand the mechanistic processes underpinning variability of CO2 uptake, for example, photosynthetic down-regulation or reversible photoinhibition induced by high light and photoprotection. However, an important next step is validating this parameterization, possibly through application to less structurally complex organisms such as single-celled algae.
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Affiliation(s)
- Zi-Piao Ye
- School of Life Sciences, Jinggangshan University, Ji'an, 343009, China
| | - David J Suggett
- School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK
| | - Piotr Robakowski
- Department of Forestry, Poznan University of Life Sciences, Wojska Polskiego 71E St., 60-625, Poznan, Poland
| | - Hua-Jing Kang
- Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
- Department of Landscape Architecture, Wenzhou Vocational & Technical College, Wenzhou, 325006, Zhejiang, China
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31
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Ye ZP, Robakowski P, Suggett DJ. A mechanistic model for the light response of photosynthetic electron transport rate based on light harvesting properties of photosynthetic pigment molecules. PLANTA 2013; 237:837-47. [PMID: 23138268 DOI: 10.1007/s00425-012-1790-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 10/15/2012] [Indexed: 05/08/2023]
Abstract
Models describing the light response of photosynthetic electron transport rate (ETR) are routinely used to determine how light absorption influences energy, reducing power and yields of primary productivity; however, no single model is currently able to provide insight into the fundamental processes that implicitly govern the variability of light absorption. Here we present development and application of a new mechanistic model of ETR for photosystem II based on the light harvesting (absorption and transfer to the core 'reaction centres') characteristics of photosynthetic pigment molecules. Within this model a series of equations are used to describe novel biophysical and biochemical characteristics of photosynthetic pigment molecules and in turn light harvesting; specifically, the eigen-absorption cross-section and the minimum average lifetime of photosynthetic pigment molecules in the excited state, which describe the ability of light absorption of photosynthetic pigment molecules and retention time of excitons in the excited state but are difficult to be measured directly. We applied this model to a series of previously collected fluorescence data and demonstrated that our model described well the light response curves of ETR, regardless of whether dynamic down-regulation of PSII occurs, for a range of photosynthetic organisms (Abies alba, Picea abies, Pinus mugo and Emiliania huxleyi). Inherent estimated parameters (e.g. maximum ETR and the saturation irradiance) by our model are in very close agreement with the measured data. Overall, our mechanistic model potentially provides novel insights into the regulation of ETR by light harvesting properties as well as dynamical down-regulation of PSII.
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Affiliation(s)
- Zi-Piao Ye
- Research Center for Jinggangshan Eco-Environmental Sciences, Jinggangshan University, Ji'an, 343009, People's Republic of China.
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32
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Ho QT, Verboven P, Yin X, Struik PC, Nicolaï BM. A microscale model for combined CO(2) diffusion and photosynthesis in leaves. PLoS One 2012; 7:e48376. [PMID: 23144870 PMCID: PMC3492360 DOI: 10.1371/journal.pone.0048376] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Accepted: 09/24/2012] [Indexed: 11/18/2022] Open
Abstract
Transport of CO(2) in leaves was investigated by combining a 2-D, microscale CO(2) transport model with photosynthesis kinetics in wheat (Triticum aestivum L.) leaves. The biophysical microscale model for gas exchange featured an accurate geometric representation of the actual 2-D leaf tissue microstructure and accounted for diffusive mass exchange of CO(2.) The resulting gas transport equations were coupled to the biochemical Farquhar-von Caemmerer-Berry model for photosynthesis. The combined model was evaluated using gas exchange and chlorophyll fluorescence measurements on wheat leaves. In general a good agreement between model predictions and measurements was obtained, but a discrepancy was observed for the mesophyll conductance at high CO(2) levels and low irradiance levels. This may indicate that some physiological processes related to photosynthesis are not incorporated in the model. The model provided detailed insight into the mechanisms of gas exchange and the effects of changes in ambient CO(2) concentration or photon flux density on stomatal and mesophyll conductance. It represents an important step forward to study CO(2) diffusion coupled to photosynthesis at the leaf tissue level, taking into account the leaf's actual microstructure.
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Affiliation(s)
- Quang Tri Ho
- Flanders Center of Postharvest Technology/BIOSYST-MeBioS, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Pieter Verboven
- Flanders Center of Postharvest Technology/BIOSYST-MeBioS, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Xinyou Yin
- Centre for Crop Systems Analysis, Wageningen University, Wageningen, The Netherlands
| | - Paul C. Struik
- Centre for Crop Systems Analysis, Wageningen University, Wageningen, The Netherlands
| | - Bart M. Nicolaï
- Flanders Center of Postharvest Technology/BIOSYST-MeBioS, Katholieke Universiteit Leuven, Leuven, Belgium
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33
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Davis PA, Hangarter RP. Chloroplast movement provides photoprotection to plants by redistributing PSII damage within leaves. PHOTOSYNTHESIS RESEARCH 2012; 112:153-61. [PMID: 22695784 DOI: 10.1007/s11120-012-9755-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 05/30/2012] [Indexed: 05/25/2023]
Abstract
Plants use light to fix carbon through the process of photosynthesis but light also causes photoinhibition, by damaging photosystem II (PSII). Plants can usually adjust their rate of PSII repair to equal the rate of damage, but under stress conditions or supersaturating light-intensities damage may exceed the rate of repair. Light-induced chloroplast movements are one of the many mechanisms plants have evolved to minimize photoinhibition. We found that chloroplast movements achieve a measure of photoprotection to PSII by altering the distribution of photoinhibition through depth in leaves. When chloroplasts are in the low-light accumulation arrangement a greater proportion of PSII damage occurs near the illuminated surface than for leaves where the chloroplasts are in the high-light avoidance arrangement. According to our findings chloroplast movements can increase the overall efficiency of leaf photosynthesis in at least two ways. The movements alter light profiles within leaves to maximize photosynthetic output and at the same time redistribute PSII damage throughout the leaf to reduce the amount of inhibition received by individual chloroplasts and prevent a decrease in photosynthetic potential.
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Affiliation(s)
- Phillip A Davis
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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34
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Hu YY, Zhang YL, Luo HH, Li W, Oguchi R, Fan DY, Chow WS, Zhang WF. Important photosynthetic contribution from the non-foliar green organs in cotton at the late growth stage. PLANTA 2012; 235:325-36. [PMID: 21904871 DOI: 10.1007/s00425-011-1511-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 08/22/2011] [Indexed: 05/25/2023]
Abstract
Non-foliar green organs are recognized as important carbon sources after leaves. However, the contribution of each organ to total yield has not been comprehensively studied in relation to the time-course of changes in surface area and photosynthetic activity of different organs at different growth stages. We studied the contribution of leaves, main stem, bracts and capsule wall in cotton by measuring their time-course of surface area development, O(2) evolution capacity and photosynthetic enzyme activity. Because of the early senescence of leaves, non-foliar organs increased their surface area up to 38.2% of total at late growth stage. Bracts and capsule wall showed less ontogenetic decrease in O(2) evolution capacity per area and photosynthetic enzyme activity than leaves at the late growth stage. The total capacity for O(2) evolution of stalks and bolls (bracts plus capsule wall) was 12.7 and 23.7% (total ca. 36.4%), respectively, as estimated by multiplying their surface area by their O(2) evolution capacity per area. We also kept the bolls (from 15 days after anthesis) or main stem (at the early full bolling stage) in darkness for comparison with non-darkened controls. Darkening the bolls and main stem reduced the boll weight by 24.1 and 9%, respectively, and the seed weight by 35.9 and 16.3%, respectively. We conclude that non-foliar organs significantly contribute to the yield at the late growth stage.
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Affiliation(s)
- Yuan-Yuan Hu
- The Key Laboratory of Oasis Eco-agriculture, Xinjiang Production and Construction Group, Shihezi University, Shihezi 832003, People's Republic of China
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35
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Gilbert ME, Pou A, Zwieniecki MA, Holbrook NM. On measuring the response of mesophyll conductance to carbon dioxide with the variable J method. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:413-25. [PMID: 21914657 PMCID: PMC3245476 DOI: 10.1093/jxb/err288] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 08/05/2011] [Accepted: 08/15/2011] [Indexed: 05/10/2023]
Abstract
The response of mesophyll conductance to CO(2) (g(m)) to environmental variation is a challenging parameter to measure with current methods. The 'variable J' technique, used in the majority of studies of g(m), assumes a one-to-one relationship between photosystem II (PSII) fluorescence and photosynthesis under non-photorespiratory conditions. When calibrating this relationship for Populus trichocarpa, it was found that calibration relationships produced using variation in light and CO(2) were not equivalent, and in all cases the relationships were non-linear-something not accounted for in previous studies. Detailed analyses were performed of whether different calibration procedures affect the observed g(m) response to CO(2). Past linear and assumed calibration methods resulted in systematic biases in the fluorescence estimates of electron transport. A sensitivity analysis on modelled data (where g(m) was held constant) demonstrated that biases in the estimation of electron transport as small as 2% (∼0.5 μmol m(-2) s(-1)) resulted in apparent changes in the relationship of g(m) to CO(2) of similar shape and magnitude to those observed with past calibration techniques. This sensitivity to biases introduced during calibrations leads to results where g(m) artefactually decreases with CO(2), assuming that g(m) is constant; if g(m) responds to CO(2), then biases associated with past calibration methods would lead to overestimates of the slope of the relationship. Non-linear calibrations were evaluated; these removed the bias present in past calibrations, but the method remained sensitive to measurement errors. Thus measurement errors, calibration non-linearities leading to bias, and the sensitivity of variable J g(m) hinders its use under conditions of varying CO(2) or light.
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36
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Scafaro AP, Von Caemmerer S, Evans JR, Atwell BJ. Temperature response of mesophyll conductance in cultivated and wild Oryza species with contrasting mesophyll cell wall thickness. PLANT, CELL & ENVIRONMENT 2011; 34:1999-2008. [PMID: 21752031 DOI: 10.1111/j.1365-3040.2011.02398.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A critical component of photosynthetic capacity is the conductance of CO(2) from intercellular airspaces to the sites of CO(2) fixation in the stroma of chloroplasts, termed mesophyll conductance (g(m)). Leaf anatomy has been identified as an important determinant of g(m). There are few studies of the temperature response of g(m) and none has examined the implications of leaf anatomy. Hence, we compared a cultivar of Oryza sativa with two wild Oryza relatives endemic to the hot northern savannah of Australia, namely Oryza meridionalis and Oryza australiensis. All three species had similar leaf anatomical properties, except that the wild relatives had significantly thicker mesophyll cell walls than O. sativa. Thicker mesophyll cell walls in the wild rice species are likely to have contributed to the reduction in g(m) , which was associated with a greater drawdown of CO(2) into chloroplasts (C(i) -C(c) ) compared with O. sativa. Mesophyll conductance increased at higher temperatures, whereas the rate of CO(2) assimilation was relatively stable between 20 and 40 °C. Consequently, C(i) -C(c) decreased for all three species as temperature increased.
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Affiliation(s)
- Andrew P Scafaro
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
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37
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Oguchi R, Douwstra P, Fujita T, Chow WS, Terashima I. Intra-leaf gradients of photoinhibition induced by different color lights: implications for the dual mechanisms of photoinhibition and for the application of conventional chlorophyll fluorometers. THE NEW PHYTOLOGIST 2011; 191:146-159. [PMID: 21418065 DOI: 10.1111/j.1469-8137.2011.03669.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
• We studied how different color lights cause gradients of photoinhibition within a leaf, to attempt to resolve the controversy of whether photon absorption by chlorophyll or by manganese (Mn) is the primary cause of photoinhibition, as suggested by the excess-energy hypothesis or the two-step hypothesis, respectively. • Lincomycin-treated leaf discs were photoinhibited by white, blue, green or red light. Combining a microfiber fluorometer, a fiber-thinning technique and a micro-manipulator enabled us to measure the chlorophyll fluorescence signals within a leaf. Photoinhibition gradients were also compared with results from various conventional fluorometers to estimate their depth of signal detection. • The severity of photoinhibition was in the descending order of blue, red and green light near the adaxial surface, and in the descending order of blue, green and red light in the deeper tissue, which correlated with the chlorophyll and the Mn absorption spectrums, respectively. These results cannot be explained by either hypothesis alone. • These data strongly suggest that both the excess-energy and the two-step mechanisms occur in photoinhibition, and fluorometers with red or blue measuring light give overestimated or underestimated F(v)/F(m) values of photoinhibited leaves compared with the whole tissue average, respectively; that is, they measured deeper or shallower leaf tissue, respectively.
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Affiliation(s)
- Riichi Oguchi
- Plant Sciences, Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
- Division of Plant Science, Research School of Biology, College of Medicine, Biology and Environment, The Australian National University, Canberra, ACT 0200, Australia
| | - Peter Douwstra
- Plant Sciences, Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
- Horticultural Supply Chains Group, Department of Plant Sciences, Wageningen University, Wageningen, the Netherlands
| | - Takashi Fujita
- Plant Sciences, Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Wah Soon Chow
- Division of Plant Science, Research School of Biology, College of Medicine, Biology and Environment, The Australian National University, Canberra, ACT 0200, Australia
| | - Ichiro Terashima
- Plant Sciences, Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
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38
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Terashima I, Hanba YT, Tholen D, Niinemets Ü. Leaf functional anatomy in relation to photosynthesis. PLANT PHYSIOLOGY 2011; 155:108-16. [PMID: 21075960 PMCID: PMC3075775 DOI: 10.1104/pp.110.165472] [Citation(s) in RCA: 308] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2010] [Accepted: 11/10/2010] [Indexed: 05/18/2023]
Affiliation(s)
- Ichiro Terashima
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
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39
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Tanaka A, Makino A. Photosynthetic research in plant science. PLANT & CELL PHYSIOLOGY 2009; 50:681-3. [PMID: 19376784 PMCID: PMC2669890 DOI: 10.1093/pcp/pcp040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
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