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A Changing Light Environment Induces Significant Lateral CO 2 Diffusion within Maize Leaves. Int J Mol Sci 2022; 23:ijms232314530. [PMID: 36498855 PMCID: PMC9736261 DOI: 10.3390/ijms232314530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/13/2022] [Accepted: 11/16/2022] [Indexed: 11/23/2022] Open
Abstract
A leaf structure with high porosity is beneficial for lateral CO2 diffusion inside the leaves. However, the leaf structure of maize is compact, and it has long been considered that lateral CO2 diffusion is restricted. Moreover, lateral CO2 diffusion is closely related to CO2 pressure differences (ΔCO2). Therefore, we speculated that enlarging the ΔCO2 between the adjacent regions inside maize leaves may result in lateral diffusion when the diffusion resistance is kept constant. Thus, the leaf structure and gas exchange of maize (C4), cotton (C3), and other species were explored. The results showed that maize and sorghum leaves had a lower mesophyll porosity than cotton and cucumber leaves. Similar to cotton, the local photosynthetic induction resulted in an increase in the ΔCO2 between the local illuminated and the adjacent unilluminated regions, which significantly reduced the respiration rate of the adjacent unilluminated region. Further analysis showed that when the adjacent region in the maize leaves was maintained under a steady high light, the photosynthesis induction in the local regions not only gradually reduced the ΔCO2 between them but also progressively increased the steady photosynthetic rate in the adjacent region. Under field conditions, the ΔCO2, respiration, and photosynthetic rate of the adjacent region were also markedly changed by fluctuating light in local regions in the maize leaves. Consequently, we proposed that enlarging the ΔCO2 between the adjacent regions inside the maize leaves results in the lateral CO2 diffusion and supports photosynthesis in adjacent regions to a certain extent under fluctuating light.
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Momayyezi M, Borsuk AM, Brodersen CR, Gilbert ME, Théroux‐Rancourt G, Kluepfel DA, McElrone AJ. Desiccation of the leaf mesophyll and its implications for CO 2 diffusion and light processing. PLANT, CELL & ENVIRONMENT 2022; 45:1362-1381. [PMID: 35141930 PMCID: PMC9314819 DOI: 10.1111/pce.14287] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 01/18/2022] [Accepted: 01/24/2022] [Indexed: 05/09/2023]
Abstract
Leaves balance CO2 and radiative absorption while maintaining water transport to maximise photosynthesis. Related species with contrasting leaf anatomy can provide insights into inherent and stress-induced links between structure and function for commonly measured leaf traits for important crops. We used two walnut species with contrasting mesophyll anatomy to evaluate these integrated exchange processes under non-stressed and drought conditions using a combination of light microscopy, X-ray microCT, gas exchange, hydraulic conductance, and chlorophyll distribution profiles through leaves. Juglans regia had thicker palisade mesophyll, higher fluorescence in the palisade, and greater low-mesophyll porosity that were associated with greater gas-phase diffusion (gIAS ), stomatal and mesophyll (gm ) conductances and carboxylation capacity. More and highly-packed mesophyll cells and bundle sheath extensions (BSEs) in Juglans microcarpa led to higher fluorescence in the spongy and in proximity to the BSEs. Both species exhibited drought-induced reductions in mesophyll cell volume, yet the associated increases in porosity and gIAS were obscured by declines in biochemical activity that decreased gm . Inherent differences in leaf anatomy between the species were linked to differences in gas exchange, light absorption and photosynthetic capacity, and drought-induced changes in leaf structure impacted performance via imposing species-specific limitations to light absorption, gas exchange and hydraulics.
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Affiliation(s)
- Mina Momayyezi
- Department of Viticulture and EnologyUniversity of CaliforniaDavisCaliforniaUSA
| | - Aleca M. Borsuk
- School of the EnvironmentYale UniversityNew HavenConnecticutUSA
| | | | | | | | | | - Andrew J. McElrone
- Department of Viticulture and EnologyUniversity of CaliforniaDavisCaliforniaUSA
- USDA‐ARSCrops Pathology and Genetics Research UnitDavisCaliforniaUSA
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Giannopoulos A, Nikolopoulos D, Bresta P, Samantas A, Reppa C, Karaboiki K, Dotsika E, Fasseas C, Liakopoulos G, Karabourniotis G. Cystoliths of Parietaria judaica can serve as an internal source of CO2 for photosynthetic assimilation when stomata are closed. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:5753-5763. [PMID: 31270538 DOI: 10.1093/jxb/erz316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 06/25/2019] [Indexed: 06/09/2023]
Abstract
The recently reported 'alarm photosynthesis' acts as a biochemical process that assimilates CO2 derived from the decomposition of calcium oxalate crystals. This study examined whether CaCO3 cystoliths could also serve as CO2 pools, fulfilling a similar role. Shoots of Parietaria judaica were subjected to carbon starvation, abscisic acid (ABA), or bicarbonate treatments, and the volume of cystoliths and the photochemical parameters of photosystem II (PSII) were determined. The size of cystoliths was reduced under carbon starvation or ABA treatments, whereas it was restored by xylem-provided bicarbonate. Under carbon starvation, ABA, or bicarbonate treatments, the photochemical efficiency of PSII was higher, while non-photochemical quenching, representing the safe dissipation of excess PSII energy due to lack of electron sinks, was lower in treated samples compared with controls. This observation suggests the involvement of ABA or other carbon starvation cues in the release of subsidiary CO2 for photosynthesis, inevitably from an internal source, which could be the cystoliths. Carbon remobilized from cystoliths can be photosynthetically assimilated, thus acting as a safety valve under stress. Together with alarm photosynthesis, these results show a tight link between leaf carbon deposits and photosynthesis.
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Affiliation(s)
- Andreas Giannopoulos
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Dimosthenis Nikolopoulos
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Panagiota Bresta
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Aris Samantas
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Chrysavgi Reppa
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Kalliopi Karaboiki
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Elissavet Dotsika
- Stable Isotope Unit, Institute of Material Science, National Centre for Scientific Research 'Demokritos', Athens, Greece
| | - Constantinos Fasseas
- Laboratory of Electron Microscopy, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Georgios Liakopoulos
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - George Karabourniotis
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
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Secchi F, Schubert A, Lovisolo C. Changes in Air CO₂ Concentration Differentially Alter Transcript Levels of NtAQP1 and NtPIP2;1 Aquaporin Genes in Tobacco Leaves. Int J Mol Sci 2016; 17:567. [PMID: 27089333 PMCID: PMC4849023 DOI: 10.3390/ijms17040567] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 03/31/2016] [Accepted: 04/01/2016] [Indexed: 01/21/2023] Open
Abstract
The aquaporin specific control on water versus carbon pathways in leaves is pivotal in controlling gas exchange and leaf hydraulics. We investigated whether Nicotiana tabacum aquaporin 1 (NtAQP1) and Nicotiana tabacum plasma membrane intrinsic protein 2;1 (NtPIP2;1) gene expression varies in tobacco leaves subjected to treatments with different CO₂ concentrations (ranging from 0 to 800 ppm), inducing changes in photosynthesis, stomatal regulation and water evaporation from the leaf. Changes in air CO₂ concentration ([CO₂]) affected net photosynthesis (Pn) and leaf substomatal [CO₂] (Ci). Pn was slightly negative at 0 ppm air CO₂; it was one-third that of ambient controls at 200 ppm, and not different from controls at 800 ppm. Leaves fed with 800 ppm [CO₂] showed one-third reduced stomatal conductance (gs) and transpiration (E), and their gs was in turn slightly lower than in 200 ppm- and in 0 ppm-treated leaves. The 800 ppm air [CO₂] strongly impaired both NtAQP1 and NtPIP2;1 gene expression, whereas 0 ppm air [CO₂], a concentration below any in vivo possible conditions and specifically chosen to maximize the gene expression alteration, increased only the NtAQP1 transcript level. We propose that NtAQP1 expression, an aquaporin devoted to CO₂ transport, positively responds to CO₂ scarcity in the air in the whole range 0-800 ppm. On the contrary, expression of NtPIP2;1, an aquaporin not devoted to CO₂ transport, is related to water balance in the leaf, and changes in parallel with gs. These observations fit in a model where upregulation of leaf aquaporins is activated at low Ci, while downregulation occurs when high Ci saturates photosynthesis and causes stomatal closure.
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Affiliation(s)
- Francesca Secchi
- Dipartimento di Scienze Agrarie, Forestali e Alimentari (DISAFA), ULF Colture arboree e Fisiologia Vegetale, Largo Paolo Braccini 2, 10095 Grugliasco (TO), Italy.
| | - Andrea Schubert
- Dipartimento di Scienze Agrarie, Forestali e Alimentari (DISAFA), ULF Colture arboree e Fisiologia Vegetale, Largo Paolo Braccini 2, 10095 Grugliasco (TO), Italy.
| | - Claudio Lovisolo
- Dipartimento di Scienze Agrarie, Forestali e Alimentari (DISAFA), ULF Colture arboree e Fisiologia Vegetale, Largo Paolo Braccini 2, 10095 Grugliasco (TO), Italy.
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Nichol CJ, Pieruschka R, Takayama K, F Rster B, Kolber Z, Rascher U, Grace J, Robinson SA, Pogson B, Osmond B. Canopy conundrums: building on the Biosphere 2 experience to scale measurements of inner and outer canopy photoprotection from the leaf to the landscape. FUNCTIONAL PLANT BIOLOGY : FPB 2012; 39:1-24. [PMID: 32480756 DOI: 10.1071/fp11255] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2011] [Accepted: 12/02/2011] [Indexed: 06/11/2023]
Abstract
Recognising that plant leaves are the fundamental productive units of terrestrial vegetation and the complexity of different environments in which they must function, this review considers a few of the ways in which these functions may be measured and potentially scaled to the canopy. Although canopy photosynthetic productivity is clearly the sum of all leaves in the canopy, we focus on the quest for 'economical insights' from measurements that might facilitate integration of leaf photosynthetic activities into canopy performance, to better inform modelling based on the 'insights of economics'. It is focussed on the reversible downregulation of photosynthetic efficiency in response to light environment and stress and summarises various xanthophyll-independent and dependent forms of photoprotection within the inner and outer canopy of woody plants. Two main themes are developed. First, we review experiments showing the retention of leaves that grow old in the shade may involve more than the 'payback times' required to recover the costs of their construction and maintenance. In some cases at least, retention of these leaves may reflect selection for distinctive properties that contribute to canopy photosynthesis through utilisation of sun flecks or provide 'back up' capacity following damage to the outer canopy. Second, we report experiments offering hope that remote sensing of photosynthetic properties in the outer canopy (using chlorophyll fluorescence and spectral reflectance technologies) may overcome problems of access and provide integrated measurements of these properties in the canopy as a whole. Finding appropriate tools to scale photosynthesis from the leaf to the landscape still presents a challenge but this synthesis identifies some measurements and criteria in the laboratory and the field that improve our understanding of inner and outer canopy processes.
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Affiliation(s)
- Caroline J Nichol
- School of GeoSciences, University of Edinburgh, West Mains Road, Edinburgh EH9 3JN, Scotland, UK
| | - Roland Pieruschka
- Institute for Bio- and Geosciences IBG 2: Plant Sciences, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Kotaro Takayama
- Laboratory of Physiological Green Systems, Department of Biomechanical Systems, Faculty of Agriculture, Ehime University, 3-5-7, Tarumi, Matsuyama 790-8566, Japan
| | - Britta F Rster
- Plant Sciences Division, Research School of Biology, Australian National University, Canberra, ACT 0200, Australia
| | - Zbigniew Kolber
- Ocean Sciences, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Uwe Rascher
- Institute for Bio- and Geosciences IBG 2: Plant Sciences, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - John Grace
- School of GeoSciences, University of Edinburgh, West Mains Road, Edinburgh EH9 3JN, Scotland, UK
| | - Sharon A Robinson
- Institute for Conservation Biology and Ecosystem Management, School of Biological Sciences, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Barry Pogson
- Plant Sciences Division, Research School of Biology, Australian National University, Canberra, ACT 0200, Australia
| | - Barry Osmond
- Plant Sciences Division, Research School of Biology, Australian National University, Canberra, ACT 0200, Australia
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Pieruschka R, Chavarría-Krauser A, Schurr U, Jahnke S. Photosynthesis in lightfleck areas of homobaric and heterobaric leaves. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:1031-9. [PMID: 20008895 PMCID: PMC2826648 DOI: 10.1093/jxb/erp368] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Revised: 11/23/2009] [Accepted: 11/24/2009] [Indexed: 05/22/2023]
Abstract
Leaves within a canopy are exposed to a spatially and temporally fluctuating light environment which may cause lateral gradients in leaf internal CO(2) concentration and diffusion between shaded and illuminated areas. In previous studies it was hypothesized that lateral CO(2) diffusion may support leaf photosynthesis, but the magnitude of this effect is still not well understood. In the present study homobaric leaves of Vicia faba or heterobaric leaves of Glycine max were illuminated with lightflecks of different sizes, mimicking sunflecks. Photosynthetic properties of the lightfleck areas were assessed with combined gas exchange measurements and chlorophyll fluorescence imaging. Lateral diffusion in homobaric leaves with an interconnected intercellular air space stimulated photosynthesis and the effect was largest in small lightfleck areas, in particular when plants were under drought stress. Such effects were not observed in the heterobaric leaves with strongly compartmented intercellular gas spaces. It is concluded that lateral diffusion may significantly contribute to photosynthesis of lightfleck areas of homobaric leaves depending on lightfleck size, lateral diffusivity, and stomatal conductance. Since homobaric leaf structures have been reported for many plant species, it is hypothesized that leaf homobary may have an impact on overall plant performance under conditions with a highly heterogeneous light environment.
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Affiliation(s)
- Roland Pieruschka
- ICG-3: Phytosphere, Forschungszentrum Jülich, D-52425 Jülich, Germany.
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