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Morgner E, Holloway-Phillips M, Basler D, Nelson DB, Kahmen A. Effects of increasing atmospheric CO 2 on leaf water δ 18O values are small and are attenuated in grasses and amplified in dicotyledonous herbs and legumes when transferred to cellulose δ 18O values. THE NEW PHYTOLOGIST 2024. [PMID: 38575849 DOI: 10.1111/nph.19713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 03/08/2024] [Indexed: 04/06/2024]
Abstract
The oxygen isotope composition of cellulose (δ18O values) has been suggested to contain information on stomatal conductance (gs) responses to rising pCO2. The extent by which pCO2 affects leaf water and cellulose δ18O values (δ18OLW and δ18OC) and the isotope processes that determine pCO2 effects on δ18OLW and δ18OC are, however, unknown. We tested the effects of pCO2 on gs, δ18OLW and δ18OC in a glasshouse experiment, where six plant species were grown under pCO2 ranging from 200 to 500 ppm. Increasing pCO2 caused a decline in gs and an increase in δ18OLW, as expected. Importantly, the effects of pCO2 on gs and δ18OLW were small and pCO2 effects on δ18OLW were not directly transferred to δ18OC but were attenuated in grasses and amplified in dicotyledonous herbs and legumes. This is likely because of functional group-specific pCO2 effects on the model parameter pxpex. Our study highlights important uncertainties when using δ18OC as a proxy for gs. Specifically, pCO2-triggered gs effects on δ18OLW and δ18OC are possibly too small to be detected in natural settings and a pCO2 effect on pxpex may render the commonly assumed negative linkage between δ18OC and gs to be incorrect, potentially confounding δ18OC based gs reconstructions.
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Affiliation(s)
- Eva Morgner
- Department of Environmental Sciences - Botany, University of Basel, 4056, Basel, Switzerland
| | | | - David Basler
- Department of Environmental Sciences - Botany, University of Basel, 4056, Basel, Switzerland
| | - Daniel B Nelson
- Department of Environmental Sciences - Botany, University of Basel, 4056, Basel, Switzerland
| | - Ansgar Kahmen
- Department of Environmental Sciences - Botany, University of Basel, 4056, Basel, Switzerland
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2
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Orlowski N, Rinderer M, Dubbert M, Ceperley N, Hrachowitz M, Gessler A, Rothfuss Y, Sprenger M, Heidbüchel I, Kübert A, Beyer M, Zuecco G, McCarter C. Challenges in studying water fluxes within the soil-plant-atmosphere continuum: A tracer-based perspective on pathways to progress. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 881:163510. [PMID: 37059146 DOI: 10.1016/j.scitotenv.2023.163510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 04/04/2023] [Accepted: 04/10/2023] [Indexed: 06/01/2023]
Abstract
Tracing and quantifying water fluxes in the hydrological cycle is crucial for understanding the current state of ecohydrological systems and their vulnerability to environmental change. Especially the interface between ecosystems and the atmosphere that is strongly mediated by plants is important to meaningfully describe ecohydrological system functioning. Many of the dynamic interactions generated by water fluxes between soil, plant and the atmosphere are not well understood, which is partly due to a lack of interdisciplinary research. This opinion paper reflects the outcome of a discussion among hydrologists, plant ecophysiologists and soil scientists on open questions and new opportunities for collaborative research on the topic "water fluxes in the soil-plant-atmosphere continuum" especially focusing on environmental and artificial tracers. We emphasize the need for a multi-scale experimental approach, where a hypothesis is tested at multiple spatial scales and under diverse environmental conditions to better describe the small-scale processes (i.e., causes) that lead to large-scale patterns of ecosystem functioning (i.e., consequences). Novel in-situ, high-frequency measurement techniques offer the opportunity to sample data at a high spatial and temporal resolution needed to understand the underlying processes. We advocate for a combination of long-term natural abundance measurements and event-based approaches. Multiple environmental and artificial tracers, such as stable isotopes, and a suite of experimental and analytical approaches should be combined to complement information gained by different methods. Virtual experiments using process-based models should be used to inform sampling campaigns and field experiments, e.g., to improve experimental designs and to simulate experimental outcomes. On the other hand, experimental data are a pre-requisite to improve our currently incomplete models. Interdisciplinary collaboration will help to overcome research gaps that overlap across different earth system science fields and help to generate a more holistic view of water fluxes between soil, plant and atmosphere in diverse ecosystems.
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Affiliation(s)
- Natalie Orlowski
- Hydrology, Faculty of Environment and Natural Resources, University of Freiburg, Freiburg im Breisgau, Germany.
| | - Michael Rinderer
- Hydrology, Faculty of Environment and Natural Resources, University of Freiburg, Freiburg im Breisgau, Germany; Geo7 AG, Bern, Switzerland
| | - Maren Dubbert
- Isotope Biogeochemistry and Gasfluxes, ZALF, Müncheberg, Germany
| | | | - Markus Hrachowitz
- Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628CN Delft, Netherlands
| | - Arthur Gessler
- Forest Dynamics, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland; Institute of Terrestrial Ecosystems, ETH Zurich, Zurich, Switzerland
| | - Youri Rothfuss
- Institute of Bio- and Geosciences, Agrosphere (IBG-3), Forschungszentrum Jülich GmbH, Jülich, Germany; Terra Teaching and Research Centre, University of Liège, Gembloux, Belgium
| | - Matthias Sprenger
- Earth and Environmental Sciences at the Lawrence Berkeley National Laboratory, Berkeley, USA
| | - Ingo Heidbüchel
- Hydrological Modelling, University of Bayreuth, Bayreuth, Germany; Hydrogeology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Angelika Kübert
- Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland
| | - Matthias Beyer
- Institute for Geoecology, Technische Universität Braunschweig, Braunschweig, Germany
| | - Giulia Zuecco
- Department of Land, Environment, Agriculture and Forestry, University of Padova, Legnaro, Italy; Department of Chemical Sciences, University of Padova, Padova, Italy
| | - Colin McCarter
- Department of Geography, Department of Biology and Chemistry, Nipissing University, North Bay, Ontario, Canada
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3
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Baca Cabrera JC, Hirl RT, Zhu J, Schäufele R, Ogée J, Schnyder H. 18 O enrichment of sucrose and photosynthetic and nonphotosynthetic leaf water in a C 3 grass-atmospheric drivers and physiological relations. PLANT, CELL & ENVIRONMENT 2023. [PMID: 37376738 DOI: 10.1111/pce.14655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 05/19/2023] [Accepted: 06/14/2023] [Indexed: 06/29/2023]
Abstract
The 18 O enrichment (Δ18 O) of leaf water affects the Δ18 O of photosynthetic products such as sucrose, generating an isotopic archive of plant function and past climate. However, uncertainty remains as to whether leaf water compartmentation between photosynthetic and nonphotosynthetic tissue affects the relationship between Δ18 O of bulk leaf water (Δ18 OLW ) and leaf sucrose (Δ18 OSucrose ). We grew Lolium perenne (a C3 grass) in mesocosm-scale, replicated experiments with daytime relative humidity (50% or 75%) and CO2 level (200, 400 or 800 μmol mol-1 ) as factors, and determined Δ18 OLW , Δ18 OSucrose and morphophysiological leaf parameters, including transpiration (Eleaf ), stomatal conductance (gs ) and mesophyll conductance to CO2 (gm ). The Δ18 O of photosynthetic medium water (Δ18 OSSW ) was estimated from Δ18 OSucrose and the equilibrium fractionation between water and carbonyl groups (εbio ). Δ18 OSSW was well predicted by theoretical estimates of leaf water at the evaporative site (Δ18 Oe ) with adjustments that correlated with gas exchange parameters (gs or total conductance to CO2 ). Isotopic mass balance and published work indicated that nonphotosynthetic tissue water was a large fraction (~0.53) of bulk leaf water. Δ18 OLW was a poor proxy for Δ18 OSucrose , mainly due to opposite Δ18 O responses of nonphotosynthetic tissue water (Δ18 Onon-SSW ) relative to Δ18 OSSW , driven by atmospheric conditions.
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Affiliation(s)
- Juan C Baca Cabrera
- Technische Universität München, TUM School of Life Sciences, Lehrstuhl für Grünlandlehre, Freising-Weihenstephan, Germany
- Forschungszentrum Jülich GmbH, Institute of Bio- and Geosciences, Agrosphere (IBG-3), Jülich, Germany
| | - Regina T Hirl
- Technische Universität München, TUM School of Life Sciences, Lehrstuhl für Grünlandlehre, Freising-Weihenstephan, Germany
| | - Jianjun Zhu
- Technische Universität München, TUM School of Life Sciences, Lehrstuhl für Grünlandlehre, Freising-Weihenstephan, Germany
| | - Rudi Schäufele
- Technische Universität München, TUM School of Life Sciences, Lehrstuhl für Grünlandlehre, Freising-Weihenstephan, Germany
| | | | - Hans Schnyder
- Technische Universität München, TUM School of Life Sciences, Lehrstuhl für Grünlandlehre, Freising-Weihenstephan, Germany
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4
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Lin W, Barbour MM, Song X. Do changes in tree-ring δ 18 O indicate changes in stomatal conductance? THE NEW PHYTOLOGIST 2022; 236:803-808. [PMID: 36200332 DOI: 10.1111/nph.18431] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 07/31/2022] [Indexed: 06/16/2023]
Affiliation(s)
- Wen Lin
- School of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518000, China
- Shenzhen Key Laboratory of Marine Bio-resource and Eco-environmental Sciences, Shenzhen University, Shenzhen, 518000, China
| | - Margaret M Barbour
- Te Aka Mātuatua - School of Science, University of Waikato, Hamilton, 3240, New Zealand
| | - Xin Song
- School of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518000, China
- Shenzhen Key Laboratory of Marine Bio-resource and Eco-environmental Sciences, Shenzhen University, Shenzhen, 518000, China
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5
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Fradera-Soler M, Grace OM, Jørgensen B, Mravec J. Elastic and collapsible: current understanding of cell walls in succulent plants. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:2290-2307. [PMID: 35167681 PMCID: PMC9015807 DOI: 10.1093/jxb/erac054] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 02/11/2022] [Indexed: 05/11/2023]
Abstract
Succulent plants represent a large functional group of drought-resistant plants that store water in specialized tissues. Several co-adaptive traits accompany this water-storage capacity to constitute the succulent syndrome. A widely reported anatomical adaptation of cell walls in succulent tissues allows them to fold in a regular fashion during extended drought, thus preventing irreversible damage and permitting reversible volume changes. Although ongoing research on crop and model species continuously reports the importance of cell walls and their dynamics in drought resistance, the cell walls of succulent plants have received relatively little attention to date, despite the potential of succulents as natural capital to mitigate the effects of climate change. In this review, we summarize current knowledge of cell walls in drought-avoiding succulents and their effects on tissue biomechanics, water relations, and photosynthesis. We also highlight the existing knowledge gaps and propose a hypothetical model for regulated cell wall folding in succulent tissues upon dehydration. Future perspectives of methodological development in succulent cell wall characterization, including the latest technological advances in molecular and imaging techniques, are also presented.
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Affiliation(s)
- Marc Fradera-Soler
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
- Royal Botanic Gardens, Kew, Richmond, Surrey, UK
- Correspondence: or
| | | | | | - Jozef Mravec
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
- Correspondence: or
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6
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Li S, Liu J, Liu H, Qiu R, Gao Y, Duan A. Role of Hydraulic Signal and ABA in Decrease of Leaf Stomatal and Mesophyll Conductance in Soil Drought-Stressed Tomato. FRONTIERS IN PLANT SCIENCE 2021; 12:653186. [PMID: 33995449 PMCID: PMC8118518 DOI: 10.3389/fpls.2021.653186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 03/30/2021] [Indexed: 06/12/2023]
Abstract
Drought reduces leaf stomatal conductance (gs) and mesophyll conductance (gm). Both hydraulic signals and chemical signals (mainly abscisic acid, ABA) are involved in regulating gs. However, it remains unclear what role the endogenous ABA plays in gm under decreasing soil moisture. In this study, the responses of gs and gm to ABA were investigated under progressive soil drying conditions and their impacts on net photosynthesis (An) and intrinsic water use efficiency (WUEi) were also analyzed. Experimental tomato plants were cultivated in pots in an environment-controlled greenhouse. Reductions of gs and gm induced a 68-78% decline of An under drought conditions. While soil water potential (Ψsoil) was over -1.01 MPa, gs reduced as leaf water potential (Ψleaf) decreased, but ABA and gm kept unchanged, which indicating gs was more sensitive to drought than gm. During Ψsoil reduction from -1.01 to -1.44 MPa, Ψleaf still kept decreasing, and both gs and gm decreased concurrently following to the sustained increases of ABA content in shoot sap. The gm was positively correlated to gs during a drying process. Compared to gs or gm, WUEi was strongly correlated with gm/gs. WUEi improved within Ψsoil range between -0.83 and -1.15 MPa. In summary, gs showed a higher sensitivity to drought than gm. Under moderate and severe drought at Ψsoil ≤ -1.01 MPa, furthermore from hydraulic signals, ABA was also involved in this co-ordination reductions of gs and gm and thereby regulated An and WUEi.
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Affiliation(s)
- Shuang Li
- Key Laboratory of Crop Water Use and Regulation, Ministry of Agriculture and Rural Affairs, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing, China
| | - Junming Liu
- Key Laboratory of Crop Water Use and Regulation, Ministry of Agriculture and Rural Affairs, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing, China
| | - Hao Liu
- Key Laboratory of Crop Water Use and Regulation, Ministry of Agriculture and Rural Affairs, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang, China
| | - Rangjian Qiu
- School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, China
| | - Yang Gao
- Key Laboratory of Crop Water Use and Regulation, Ministry of Agriculture and Rural Affairs, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang, China
| | - Aiwang Duan
- Key Laboratory of Crop Water Use and Regulation, Ministry of Agriculture and Rural Affairs, Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang, China
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7
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Polishchuk OV. Stress-Related Changes in the Expression and Activity of Plant Carbonic Anhydrases. PLANTA 2021; 253:58. [PMID: 33532871 DOI: 10.1007/s00425-020-03553-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 12/23/2020] [Indexed: 05/17/2023]
Abstract
The data on stress-related changes in the expression and activity of plant carbonic anhydrases (CAs) suggest that they are generally upregulated at moderate stress severity. This indicates probable involvement of CAs in adaptation to drought, high salinity, heat, high light, Ci deficit, and excess bicarbonate. The changes in CA levels under cold stress are less studied and generally represented by the downregulation of CAs excepting βCA2. Excess Cd2+ and deficit of Zn2+ specifically reduce CA activity and reduce its synthesis. Probable roles of βCAs in stress adaptation include stomatal closure, ROS scavenging and partial compensation for decreased mesophyll CO2 conductance. βCAs play contrasting roles in pathogen responses, interacting with phytohormone signaling networks. Their role can be either negative or positive, probably depending on the host-pathogen system, pathogen initial titer, and levels of ·NO and ROS. It is still not clear why CAs are suppressed under severe stress levels. It should be noted, that the role of βCAs in the facilitation of CO2 diffusion and their involvement in redox signaling or ROS detoxication are potentially antagonistic, as they are inactivated by oxidation or nitrosylation. Interestingly, some chloroplastic βCAs may be relocated to the cytoplasm under stress conditions, but the physiological meaning of this effect remains to be studied.
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Affiliation(s)
- O V Polishchuk
- Membranology and Phytochemistry Department, M.G. Kholodny Institute of Botany of NAS of Ukraine, 2 Tereshchenkivska Str, Kyiv, 01004, Ukraine.
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8
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Barbour MM, Loucos KE, Lockhart EL, Shrestha A, McCallum D, Simonin KA, Song X, Griffani DS, Farquhar GD. Can hydraulic design explain patterns of leaf water isotopic enrichment in C 3 plants? PLANT, CELL & ENVIRONMENT 2021; 44:432-444. [PMID: 33175397 DOI: 10.1111/pce.13943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Revised: 10/17/2020] [Accepted: 10/29/2020] [Indexed: 06/11/2023]
Abstract
H2 18 O enrichment develops when leaves transpire, but an accurate generalized mechanistic model has proven elusive. We hypothesized that leaf hydraulic architecture may affect the degree to which gradients in H2 18 O develop within leaves, influencing bulk leaf stable oxygen isotope enrichment (ΔL ) and the degree to which the Péclet effect is relevant in leaves. Leaf hydraulic design predicted the relevance of a Péclet effect to ΔL in 19 of the 21 species tested. Leaves with well-developed hydraulic connections between the vascular tissue and the epidermal cells through bundle sheath extensions and clear distinctions between palisade and spongy mesophyll layers (while the mesophyll is hydraulically disconnected) may have velocities of the transpiration stream such that gradients in H2 18 O develop and are expressed in the mesophyll. In contrast, in leaves where the vascular tissue is hydraulically disconnected from the epidermal layers, or where all mesophyll cells are well connected to the transpiration stream, velocities within the liquid transport pathways may be low enough that gradients in H2 18 O are very small. Prior knowledge of leaf hydraulic design allows informed selection of the appropriate ΔL modelling framework.
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Affiliation(s)
- Margaret M Barbour
- The University of Sydney, School of Life and Environmental Sciences, Camperdown, New South Wales, Australia
- The University of Waikato, School of Science, Hamilton, New Zealand
| | - Karen E Loucos
- The University of Sydney, School of Life and Environmental Sciences, Camperdown, New South Wales, Australia
| | - Erin L Lockhart
- The University of Sydney, School of Life and Environmental Sciences, Camperdown, New South Wales, Australia
| | - Arjina Shrestha
- The University of Sydney, School of Life and Environmental Sciences, Camperdown, New South Wales, Australia
| | - Daniel McCallum
- The University of Sydney, School of Life and Environmental Sciences, Camperdown, New South Wales, Australia
| | - Kevin A Simonin
- Department of Biology, San Francisco State University, San Francisco, California, USA
| | - Xin Song
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, Guangdong, China
| | - Danielle S Griffani
- Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Graham D Farquhar
- Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
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9
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Ma WT, Tcherkez G, Wang XM, Schäufele R, Schnyder H, Yang Y, Gong XY. Accounting for mesophyll conductance substantially improves 13 C-based estimates of intrinsic water-use efficiency. THE NEW PHYTOLOGIST 2021; 229:1326-1338. [PMID: 32984961 DOI: 10.1111/nph.16958] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/14/2020] [Indexed: 05/08/2023]
Abstract
Carbon isotope discrimination (Δ) has been used widely to infer intrinsic water-use efficiency (iWUE) of C3 plants, a key parameter linking carbon and water fluxes. Despite the essential role of mesophyll conductance (gm ) in photosynthesis and Δ, its effect on Δ-based predictions of iWUE has generally been neglected. Here, we derive a mathematical expression of iWUE as a function of Δ that includes gm (iWUEmes ) and exploits the gm -stomatal conductance (gsc ) relationship across drought-stress levels and plant functional groups (deciduous or semideciduous woody, evergreen woody and herbaceous species) in a global database. iWUEmes was further validated with an independent dataset of online-Δ and CO2 and H2 O gas exchange measurements with seven species. Drought stress reduced gsc and gm by nearly one-half across all plant functional groups, but had no significant effect on the gsc : gm ratio, with a well supported value of 0.79 ± 0.07 (95% CI, n = 198). gm was negatively correlated to iWUE. Incorporating the gsc : gm ratio greatly improved estimates of iWUE, compared with calculations that assumed infinite gm . The inclusion of the gsc : gm ratio, fixed at 0.79 when gm was unknown, proved desirable to eliminate significant errors in estimating iWUE from Δ across various C3 vegetation types.
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Affiliation(s)
- Wei Ting Ma
- Key Laboratory for Subtropical Mountain Ecology (Ministry of Science and Technology and Fujian Province Funded), College of Geographical Sciences, Fujian Normal University, Fuzhou, 350007, China
| | - Guillaume Tcherkez
- Research School of Biology, ANU College of Medicine, Biology and Environment, Australian National University, Canberra, ACT 0200, Australia
- Institut de Recherche en Horticulture et Semences, INRAe, Université d'Angers, 42 rue Georges Morel, Beaucouzé, 49070, France
| | - Xu Ming Wang
- Key Laboratory for Subtropical Mountain Ecology (Ministry of Science and Technology and Fujian Province Funded), College of Geographical Sciences, Fujian Normal University, Fuzhou, 350007, China
| | - Rudi Schäufele
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, Freising, 85354, Germany
| | - Hans Schnyder
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, Freising, 85354, Germany
| | - Yusheng Yang
- Key Laboratory for Subtropical Mountain Ecology (Ministry of Science and Technology and Fujian Province Funded), College of Geographical Sciences, Fujian Normal University, Fuzhou, 350007, China
| | - Xiao Ying Gong
- Key Laboratory for Subtropical Mountain Ecology (Ministry of Science and Technology and Fujian Province Funded), College of Geographical Sciences, Fujian Normal University, Fuzhou, 350007, China
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10
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Kannenberg SA, Fiorella RP, Anderegg WRL, Monson RK, Ehleringer JR. Seasonal and diurnal trends in progressive isotope enrichment along needles in two pine species. PLANT, CELL & ENVIRONMENT 2021; 44:143-155. [PMID: 33058213 DOI: 10.1111/pce.13915] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 10/09/2020] [Accepted: 10/12/2020] [Indexed: 06/11/2023]
Abstract
The Craig-Gordon type (C-G) leaf water isotope enrichment models assume a homogeneous distribution of enriched water across the leaf surface, despite observations that Δ18 O can become increasingly enriched from leaf base to tip. Datasets of this 'progressive isotope enrichment' are limited, precluding a comprehensive understanding of (a) the magnitude and variability of progressive isotope enrichment, and (b) how progressive enrichment impacts the accuracy of C-G leaf water model predictions. Here, we present observations of progressive enrichment in two conifer species that capture seasonal and diurnal variability in environmental conditions. We further examine which leaf water isotope models best capture the influence of progressive enrichment on bulk needle water Δ18 O. Observed progressive enrichment was large and equal in magnitude across both species. The magnitude of this effect fluctuated seasonally in concert with vapour pressure deficit, but was static in the face of diurnal cycles in meteorological conditions. Despite large progressive enrichment, three variants of the C-G model reasonably successfully predicted bulk needle Δ18 O. Our results thus suggest that the presence of progressive enrichment does not impact the predictive success of C-G models, and instead yields new insight regarding the physiological and anatomical mechanisms that cause progressive isotope enrichment.
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Affiliation(s)
- Steven A Kannenberg
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Richard P Fiorella
- Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah, USA
| | | | - Russell K Monson
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, Colorado, USA
| | - James R Ehleringer
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
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11
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Brunel-Saldias N, Ferrio JP, Elazab A, Orellana M, del Pozo A. Root Architecture and Functional Traits of Spring Wheat Under Contrasting Water Regimes. FRONTIERS IN PLANT SCIENCE 2020; 11:581140. [PMID: 33262777 PMCID: PMC7686047 DOI: 10.3389/fpls.2020.581140] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/07/2020] [Indexed: 05/29/2023]
Abstract
Wheat roots are known to play an important role in the yield performance under water-limited (WL) conditions. Three consecutive year trials (2015, 2016, and 2017) were conducted in a glasshouse in 160 cm length tubes on a set of spring wheat (Triticum aestivum L.) genotypes under contrasting water regimes (1) to assess genotypic variability in root weight density (RWD) distribution in the soil profile, biomass partitioning, and total water used; and (2) to determine the oxygen and hydrogen isotopic signatures of plant and soil water in order to evaluate the contribution of shallow and deep soil water to plant water uptake and the evaporative enrichment of these isotopes in the leaf as a surrogate for plant transpiration. In the 2015 trial under well-watered (WW) conditions, the aerial biomass (AB) was not significantly different among 15 wheat genotypes, while the total root biomass and the RWD distribution in the soil profile were significantly different. In the 2016 and 2017 trials, a subset of five genotypes from the 2015 trial was grown under WW and WL regimes. The water deficit significantly reduced AB only in 2016. The water regimes did not significantly affect the root biomass and root biomass distribution in the soil depths for both the 2016 and 2017 trials. The study results highlighted that under a WL regime, the production of thinner roots with low biomass is more beneficial for increasing the water uptake than the production of large thick roots. The models applied to estimate the relative contribution of the plant's primary water sources (shallow or deep soil water) showed large interindividual variability in soil, and plant water isotopic composition resulted in large uncertainties in the model estimates. On the other side, the combined information of root architecture and the leaf stable isotope signatures could explain plant water status.
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Affiliation(s)
- Nidia Brunel-Saldias
- Centro de Mejoramiento Genético y Fenómica Vegetal, Facultad de Ciencias Agrarias, Universidad de Talca, Talca, Chile
| | - Juan Pedro Ferrio
- Fundacion Agencia Aragonesa para la Investigacion y el Desarrollo (ARAID), Zaragoza, Spain
- Department of Forest Resources, Agrifood Research and Technology Center of Aragón (CITA), Zaragoza, Spain
- Department of Botany, Faculty of Natural Sciences and Oceanography, University of Concepción, Concepción, Chile
| | - Abdelhalim Elazab
- Centro de Mejoramiento Genético y Fenómica Vegetal, Facultad de Ciencias Agrarias, Universidad de Talca, Talca, Chile
| | - Massiel Orellana
- Centro de Mejoramiento Genético y Fenómica Vegetal, Facultad de Ciencias Agrarias, Universidad de Talca, Talca, Chile
| | - Alejandro del Pozo
- Centro de Mejoramiento Genético y Fenómica Vegetal, Facultad de Ciencias Agrarias, Universidad de Talca, Talca, Chile
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12
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Timofeeva G, Treydte K, Bugmann H, Salmon Y, Rigling A, Schaub M, Vollenweider P, Siegwolf R, Saurer M. How does varying water supply affect oxygen isotope variations in needles and tree rings of Scots pine? TREE PHYSIOLOGY 2020; 40:1366-1380. [PMID: 32589748 DOI: 10.1093/treephys/tpaa082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 04/01/2020] [Accepted: 06/19/2020] [Indexed: 06/11/2023]
Abstract
In many regions, drought is suspected to be a cause of Scots pine decline and mortality, but the underlying physiological mechanisms remain unclear. Because of their relationship to ecohydrological processes, δ18O values in tree rings are potentially useful for deciphering long-term physiological responses and tree adaptation to increasing drought. We therefore analyzed both needle- and stem-level isotope fractionations in mature trees exposed to varying water supply. In a first experiment, we investigated seasonal δ18O variations in soil and needle water of Scots pine in a dry inner Alpine valley in Switzerland, comparing drought-stressed trees with trees that were irrigated for more than 10 years. In a second experiment, we analyzed twentieth-century δ18O variations in tree rings of the same forest, including a group of trees that had recently died. We observed less 18O enrichment in needle water of drought-stressed compared with irrigated trees. We applied different isotope fractionation models to explain these results, including the Péclet and the two-pool correction, which considers the ratio of unenriched xylem water in the needles to total needle water. Based on anatomical measurements, we found this ratio to be unchanged in drought-stressed needles, although they were shorter. The observed lower 18O enrichment in needles of stressed trees was therefore likely caused by increased effective path length for water movement within the leaf lamina. In the tree-ring study, we observed lower δ18O values in tree rings of dead trees compared with survivors during several decades prior to their death. These lower values in declining trees are consistent with the lower needle water 18O enrichment observed for drought-stressed compared with irrigated trees, suggesting that this needle-level signal is reflected in the tree rings, although changes in rooting depth could also play a role. Our study demonstrates that long-term effects of drought are reflected in the tree-ring δ18O values, which helps to provide a better understanding of past tree physiological changes of Scots pine.
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Affiliation(s)
- Galina Timofeeva
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), Villigen 5232, Switzerland
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
- Forest Ecology, Institute of Terrestrial Ecosystems, ETH Zurich, Zurich 8092, Switzerland
| | - Kerstin Treydte
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
| | - Harald Bugmann
- Forest Ecology, Institute of Terrestrial Ecosystems, ETH Zurich, Zurich 8092, Switzerland
| | - Yann Salmon
- Department of Physics, University of Helsinki, Helsinki 00014, Finland
- School of GeoSciences, University of Edinburgh, Edinburgh EH9 3FF, UK
| | - Andreas Rigling
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
| | - Marcus Schaub
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
| | - Pierre Vollenweider
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
| | - Rolf Siegwolf
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), Villigen 5232, Switzerland
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
| | - Matthias Saurer
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), Villigen 5232, Switzerland
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf 8903, Switzerland
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Sonawane BV, Cousins AB. Mesophyll CO 2 conductance and leakiness are not responsive to short- and long-term soil water limitations in the C 4 plant Sorghum bicolor. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:1590-1602. [PMID: 32438487 DOI: 10.1111/tpj.14849] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 04/30/2020] [Accepted: 05/05/2020] [Indexed: 05/13/2023]
Abstract
Breeding economically important C4 crops for enhanced whole-plant water-use efficiency (WUEplant ) is needed for sustainable agriculture. WUEplant is a complex trait and an efficient phenotyping method that reports on components of WUEplant , such as intrinsic water-use efficiency (WUEi , the rate of leaf CO2 assimilation relative to water loss via stomatal conductance), is needed. In C4 plants, theoretical models suggest that leaf carbon isotope composition (δ13 C), when the efficiency of the CO2 -concentrating mechanism (leakiness, ϕ) remains constant, can be used to screen for WUEi . The limited information about how ϕ responds to water limitations confines the application of δ13 C for WUEi screening of C4 crops. The current research aimed to test the response of ϕ to short- or long-term moderate water limitations, and the relationship of δ13 C with WUEi and WUEplant , by addressing potential mesophyll CO2 conductance (gm ) and biochemical limitations in the C4 plant Sorghum bicolor. We demonstrate that gm and ϕ are not responsive to short- or long-term water limitations. Additionally, δ13 C was not correlated with gas-exchange estimates of WUEi under short- and long-term water limitations, but showed a significant negative relationship with WUEplant . The observed association between the δ13 C and WUEplant suggests an intrinsic link of δ13 C with WUEi in this C4 plant, and can potentially be used as a screening tool for WUEplant in sorghum.
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Affiliation(s)
- Balasaheb V Sonawane
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
| | - Asaph B Cousins
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
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14
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Wang X, Du T, Huang J, Peng S, Xiong D. Leaf hydraulic vulnerability triggers the decline in stomatal and mesophyll conductance during drought in rice. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:4033-4045. [PMID: 29788146 PMCID: PMC6054168 DOI: 10.1093/jxb/ery188] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 05/14/2018] [Indexed: 05/21/2023]
Abstract
Understanding the physiological responses of crops to drought is important for ensuring sustained crop productivity under climate change, which is expected to exacerbate the frequency and intensity of periods of drought. Drought responses involve multiple traits, and the correlations between these traits are poorly understood. Using a variety of techniques, we estimated the changes in gas exchange, leaf hydraulic conductance, and leaf turgor in rice (Oryza sativa) in response to both short- and long-term soil drought. We performed a photosynthetic limitation analysis to quantify the contributions of each limiting factor to the resultant overall decrease in photosynthesis during drought. Biomass, leaf area, and leaf width significantly decreased during the 2-week drought treatment, but leaf mass per area and leaf vein density increased. Light-saturated photosynthetic rate declined dramatically during soil drought, mainly due to the decrease in stomatal conductance (gs) and mesophyll conductance (gm). Stomatal modeling suggested that the decline in leaf hydraulic conductance explained most of the decrease in stomatal closure during the drought treatment, and may also trigger the drought-related decrease of stomatal conductance and mesophyll conductance. The results of this study provide insight into the regulation of carbon assimilation under drought conditions.
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Affiliation(s)
- Xiaoxiao Wang
- National Key Laboratory of Crop Genetic Improvement, MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Tingting Du
- National Key Laboratory of Crop Genetic Improvement, MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Jianliang Huang
- National Key Laboratory of Crop Genetic Improvement, MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Shaobing Peng
- National Key Laboratory of Crop Genetic Improvement, MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Dongliang Xiong
- National Key Laboratory of Crop Genetic Improvement, MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
- Department of Plant Sciences, University of California, Davis, CA, USA
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15
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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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16
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Prieto I, Querejeta JI, Segrestin J, Volaire F, Roumet C. Leaf carbon and oxygen isotopes are coordinated with the leaf economics spectrum in Mediterranean rangeland species. Funct Ecol 2017. [DOI: 10.1111/1365-2435.13025] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Iván Prieto
- CEFECNRSUniv MontpellierUniv Paul Valéry Montpellier 3EPHEIRD Montpellier France
- Centro de Edafología y Biología Aplicada del Segura‐Consejo Superior de Investigaciones Científicas (CEBAS‐CSIC) Murcia Spain
| | - José I. Querejeta
- Centro de Edafología y Biología Aplicada del Segura‐Consejo Superior de Investigaciones Científicas (CEBAS‐CSIC) Murcia Spain
| | - Jules Segrestin
- CEFECNRSUniv MontpellierUniv Paul Valéry Montpellier 3EPHEIRD Montpellier France
| | - Florence Volaire
- CEFEINRACNRSUniv. MontpellierUniv Paul Valéry Montpellier 3EPHEIRD Montpellier France
| | - Catherine Roumet
- CEFECNRSUniv MontpellierUniv Paul Valéry Montpellier 3EPHEIRD Montpellier France
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17
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Growth and Physiology of Senegalia senegal (L.) Britton Seedlings as Influenced by Seed Origin and Salinity and Fertility Treatments. FORESTS 2017. [DOI: 10.3390/f8100388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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18
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Bögelein R, Thomas FM, Kahmen A. Leaf water 18 O and 2 H enrichment along vertical canopy profiles in a broadleaved and a conifer forest tree. PLANT, CELL & ENVIRONMENT 2017; 40:1086-1103. [PMID: 28042668 DOI: 10.1111/pce.12895] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 12/16/2016] [Accepted: 12/28/2016] [Indexed: 06/06/2023]
Abstract
Distinguishing meteorological and plant-mediated drivers of leaf water isotopic enrichment is prerequisite for ecological interpretations of stable hydrogen and oxygen isotopes in plant tissue. We measured input and leaf water δ2 H and δ18 O as well as micrometeorological and leaf morpho-physiological variables along a vertical gradient in a mature angiosperm (European beech) and gymnosperm (Douglas fir) tree. We used these variables and different enrichment models to quantify the influence of Péclet and non-steady state effects and of the biophysical drivers on leaf water enrichment. The two-pool model accurately described the diurnal variation of leaf water enrichment. The estimated unenriched water fraction was linked to leaf dry matter content across the canopy heights. Non-steady state effects and reduced stomatal conductance caused a higher enrichment of Douglas fir compared to beech leaf water. A dynamic effect analyses revealed that the light-induced vertical gradients of stomatal conductance and leaf temperature outbalanced each other in their effects on evaporative enrichment. We conclude that neither vertical canopy gradients nor the Péclet effect is important for estimates and interpretation of isotopic leaf water enrichment in hypostomatous trees. Contrarily, species-specific non-steady state effects and leaf temperatures as well as the water vapour isotope composition need careful consideration.
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Affiliation(s)
- Rebekka Bögelein
- Faculty of Regional and Environmental Sciences - Geobotany, University of Trier, 54296, Trier, Germany
| | - Frank M Thomas
- Faculty of Regional and Environmental Sciences - Geobotany, University of Trier, 54296, Trier, Germany
| | - Ansgar Kahmen
- Department of Environmental Sciences - Botany, University of Basel, 4056, Basel, Switzerland
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19
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Barbour MM, Farquhar GD, Buckley TN. Leaf water stable isotopes and water transport outside the xylem. PLANT, CELL & ENVIRONMENT 2017; 40:914-920. [PMID: 27739589 DOI: 10.1111/pce.12845] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 09/12/2016] [Accepted: 09/19/2016] [Indexed: 06/06/2023]
Abstract
How water moves through leaves, and where the phase change from liquid to vapour occurs within leaves, remain largely mysterious. Some time ago, we suggested that the stable isotope composition of leaf water may contain information on transport pathways beyond the xylem, through differences in the development of gradients in enrichment within the various pathways. Subsequent testing of this suggestion provided ambiguous results and even questioned the existence of gradients in enrichment within the mesophyll. In this review, we bring together recent theoretical developments in understanding leaf water transport pathways and stable isotope theory to map a path for future work into understanding pathways of water transport and leaf water stable isotope composition. We emphasize the need for a spatially, anatomically and isotopically explicit model of leaf water transport.
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Affiliation(s)
- M M Barbour
- Centre for Carbon, Water and Food, University of Sydney, Brownlow Hill, New South Wales, 2570, Australia
| | - G D Farquhar
- Research School of Biology, Australian National University, Acton, Australian Capital Territory, 0200, Australia
| | - T N Buckley
- Plant Breeding Institute, Faculty of Agriculture and Environment, The University of Sydney, Narrabri, New South Wales, 2390, Australia
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20
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Barbour MM. Understanding regulation of leaf internal carbon and water transport using online stable isotope techniques. THE NEW PHYTOLOGIST 2017; 213:83-88. [PMID: 27651090 DOI: 10.1111/nph.14171] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 07/12/2016] [Indexed: 06/06/2023]
Abstract
83 I. 83 II. 84 III. 84 IV. 85 V. 86 VI. 86 VII. 86 87 References 87 SUMMARY: The balance of carbon dioxide (CO2 ) and water vapour exchange between leaves and the atmosphere is strongly controlled by stomatal conductance. However, the influence of transport processes within leaves has recently been gaining prominence. Stable isotope techniques are at the forefront of understanding transport within leaves and the recent development of online, real-time optical isotope analysers has paved the way for new questions to be asked. In this insight, I outline these new techniques and the questions they can potentially address, including assessing possible coordination between mesophyll conductance to CO2 and leaf hydraulic conductance.
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Affiliation(s)
- Margaret M Barbour
- Centre for Carbon, Water and Food, the University of Sydney, 380 Werombi Road, Brownlow Hill, Sydney, NSW, 2570, Australia
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21
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Cernusak LA, Barbour MM, Arndt SK, Cheesman AW, English NB, Feild TS, Helliker BR, Holloway-Phillips MM, Holtum JAM, Kahmen A, McInerney FA, Munksgaard NC, Simonin KA, Song X, Stuart-Williams H, West JB, Farquhar GD. Stable isotopes in leaf water of terrestrial plants. PLANT, CELL & ENVIRONMENT 2016; 39:1087-102. [PMID: 26715126 DOI: 10.1111/pce.12703] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 11/21/2015] [Accepted: 12/16/2015] [Indexed: 05/14/2023]
Abstract
Leaf water contains naturally occurring stable isotopes of oxygen and hydrogen in abundances that vary spatially and temporally. When sufficiently understood, these can be harnessed for a wide range of applications. Here, we review the current state of knowledge of stable isotope enrichment of leaf water, and its relevance for isotopic signals incorporated into plant organic matter and atmospheric gases. Models describing evaporative enrichment of leaf water have become increasingly complex over time, reflecting enhanced spatial and temporal resolution. We recommend that practitioners choose a model with a level of complexity suited to their application, and provide guidance. At the same time, there exists some lingering uncertainty about the biophysical processes relevant to patterns of isotopic enrichment in leaf water. An important goal for future research is to link observed variations in isotopic composition to specific anatomical and physiological features of leaves that reflect differences in hydraulic design. New measurement techniques are developing rapidly, enabling determinations of both transpired and leaf water δ(18) O and δ(2) H to be made more easily and at higher temporal resolution than previously possible. We expect these technological advances to spur new developments in our understanding of patterns of stable isotope fractionation in leaf water.
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Affiliation(s)
- Lucas A Cernusak
- College of Marine and Environmental Sciences, James Cook University, Cairns, Australia
| | - Margaret M Barbour
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, Camden, Australia
| | - Stefan K Arndt
- School of Ecosystem and Forest Sciences, The University of Melbourne, Richmond, Australia
| | - Alexander W Cheesman
- College of Marine and Environmental Sciences, James Cook University, Cairns, Australia
| | - Nathan B English
- College of Marine and Environmental Sciences, James Cook University, Townsville, Australia
| | - Taylor S Feild
- College of Marine and Environmental Sciences, James Cook University, Townsville, Australia
| | - Brent R Helliker
- Department of Biology, University of Pennsylvania, Philadelphia, USA
| | | | - Joseph A M Holtum
- College of Marine and Environmental Sciences, James Cook University, Townsville, Australia
| | - Ansgar Kahmen
- Department of Environmental Sciences-Botany, University of Basel, Basel, Switzerland
| | | | - Niels C Munksgaard
- College of Science, Technology and Engineering, James Cook University, Cairns, Australia
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Australia
| | - Kevin A Simonin
- Department of Biology, San Francisco State University, San Francisco, USA
| | - Xin Song
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, Camden, Australia
| | | | - Jason B West
- Department of Ecosystem Science and Management, Texas A&M University, College Station, USA
| | - Graham D Farquhar
- Research School of Biology, The Australian National University, Canberra, Australia
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22
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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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23
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Saurer M, Kirdyanov AV, Prokushkin AS, Rinne KT, Siegwolf RTW. The impact of an inverse climate-isotope relationship in soil water on the oxygen-isotope composition of Larix gmelinii in Siberia. THE NEW PHYTOLOGIST 2016; 209:955-964. [PMID: 26610186 DOI: 10.1111/nph.13759] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 10/03/2015] [Indexed: 06/05/2023]
Abstract
Stable oxygen isotope ratios (δ(18) O) in trees from high latitude ecosystems are valuable sources of information for recent and past environmental changes, but the interpretation is hampered by the complex hydrology of forests growing under permafrost conditions, where only a shallow layer of soil thaws in summer. We investigated larch trees (Larix gmelinii) at two sites with contrasting soil conditions in Siberia and determined δ(18) O of water from different soil depths, roots, twigs, and needles as well as δ(18) O of soluble carbohydrates regularly over two growing seasons. A comparison of results from the 2 yrs revealed an unexpected 'inverse' climate-isotope relationship, as dry and warm summer conditions resulted in lower soil and root δ(18) O values. This was due to a stronger uptake of isotopically depleted water pools originating from melted permafrost or previous winter snow. We developed a conceptual framework that considers the dependence of soil water profiles on climatic conditions for explaining δ(18) O in needle water, needle soluble carbohydrates and stem cellulose. The negative feedback of drought conditions on the source isotope value could explain decreasing tree-ring δ(18) O trends in a warming climate and is likely relevant in many ecosystems, where a soil isotope gradient with depth is observed.
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Affiliation(s)
- Matthias Saurer
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Alexander V Kirdyanov
- V.N. Sukachev Institute of Forest, Siberian Branch of the Russian Academy of Sciences, Krasnoyarsk, 660036, Russia
| | - Anatoly S Prokushkin
- V.N. Sukachev Institute of Forest, Siberian Branch of the Russian Academy of Sciences, Krasnoyarsk, 660036, Russia
| | - Katja T Rinne
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Rolf T W Siegwolf
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, 5232, Switzerland
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24
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Roden J, Kahmen A, Buchmann N, Siegwolf R. The enigma of effective path length for (18) O enrichment in leaf water of conifers. PLANT, CELL & ENVIRONMENT 2015; 38:2551-2565. [PMID: 26037826 DOI: 10.1111/pce.12568] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Revised: 05/02/2015] [Accepted: 05/04/2015] [Indexed: 06/04/2023]
Abstract
The Péclet correction is often used to predict leaf evaporative enrichment and requires an estimate of effective path length (L). Studies to estimate L in conifer needles have produced unexpected patterns based on Péclet theory and leaf anatomy. We exposed seedlings of six conifer species to different vapour pressure deficits (VPD) in controlled climate chambers to produce steady-state leaf water enrichment (in (18) O). We measured leaf gas exchange, stable oxygen isotopic composition (δ(18) O) of input and plant waters as well as leaf anatomical characteristics. Variation in bulk needle water δ(18) O was strongly related to VPD. Conifer needles had large amounts of water within the vascular strand that was potentially unenriched (up to 40%). Both standard Craig-Gordon and Péclet models failed to accurately predict conifer leaf water δ(18) O without taking into consideration the unenriched water in the vascular strand and variable L. Although L was linearly related to mesophyll thickness, large within-species variation prevented the development of generalizations that could allow a broader use of the Péclet effect in predictive models. Our results point to the importance of within needle water pools and isolating mechanisms that need further investigation in order to integrate Péclet corrections with 'two compartment' leaf water concepts.
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Affiliation(s)
- John Roden
- Department of Biology, Southern Oregon University, Ashland, OR, 97520, USA
| | - Ansgar Kahmen
- Department of Environmental Sciences - Botany, University of Basel, 4056, Basel, Switzerland
| | - Nina Buchmann
- Department of Environmental Systems Science, Eidgenössische Technische Hochschule, 8092, Zürich
| | - Rolf Siegwolf
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, 5232, Villigen, Switzerland
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25
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Song X, Loucos KE, Simonin KA, Farquhar GD, Barbour MM. Measurements of transpiration isotopologues and leaf water to assess enrichment models in cotton. THE NEW PHYTOLOGIST 2015; 206:637-646. [PMID: 25643590 DOI: 10.1111/nph.13296] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 12/10/2014] [Indexed: 06/04/2023]
Abstract
The two-pool and Péclet effect models represent two theories describing mechanistic controls underlying leaf water oxygen isotope composition at the whole-leaf level (δ(18) OL ). To test these models, we used a laser spectrometer coupled to a gas-exchange cuvette to make online measurements of δ(18) O of transpiration (δ(18) Otrans ) and transpiration rate (E) in 61 cotton (Gossypium hirsutum) leaves. δ(18) Otrans measurements permitted direct calculation of δ(18) O at the sites of evaporation (δ(18) Oe ) which, combined with values of δ(18) OL from the same leaves, allowed unbiased estimation of the proportional deviation of enrichment of δ(18) OL from that of δ(18) Oe (f) under both steady-state (SS) and non-steady-state (NSS) conditions. Among all leaves measured, f expressed relative to both δ(18) O of transpired water (ftrans ) and source water (fsw ) remained relatively constant with a mean ± SD of 0.11 ± 0.05 and 0.13 ± 0.05, respectively, regardless of variation in E spanning 0.8-9.1 mmol m(-2) s(-1) . Neither ftrans nor fsw exhibited a significant difference between the SS and NSS leaves at the P < 0.05 level. Our results suggest that the simpler two-pool model is adequate for predicting cotton leaf water enrichment at the whole-leaf level. We discuss the implications of adopting a two-pool concept for isotopic applications in ecological studies.
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Affiliation(s)
- Xin Song
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Rd, NSW, 2570, Australia
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Larcher L, Hara-Nishimura I, Sternberg L. Effects of stomatal density and leaf water content on the ¹⁸O enrichment of leaf water. THE NEW PHYTOLOGIST 2015; 206:141-151. [PMID: 25408145 DOI: 10.1111/nph.13154] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 10/07/2014] [Indexed: 06/04/2023]
Abstract
Leaf water isotopic composition is imprinted in several biomarkers of interest and it is imperative that we understand the isotopic enrichment of leaf water. Here, we test the effect of stomatal density and leaf water content on the oxygen isotopic composition of leaf water in transgenic Arabidopsis plants expressing different stomatal densities, and several other species showing a range of stomatal density. We grew Arabidopsis plants hydroponically and collected other species in the field. Stomatal density and leaf water content were determined for each plant. We measured transpiration and extracted leaf water for isotopic determination. Using these measurements and the current leaf water isotope model, we calculated several of the parameters related to leaf water isotopic enrichment. High stomatal density promoted leaf water isotope enrichment. No conclusion, however, can be drawn regarding the effect of leaf water content on leaf water isotope enrichment. Factors such as transpiration might mask the effect of stomatal density on leaf water isotopic enrichment. We propose a method by which stomatal density can be incorporated in the current Peclet model of leaf water isotope enrichment. These findings have important applications in the use of plant-based metabolic proxies in paleoclimate studies.
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Affiliation(s)
- Leticia Larcher
- Programa de Pós Graduação em Ecologia e Conservação, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
| | - Ikuko Hara-Nishimura
- Graduate School of Science, Department of Botany, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Leonel Sternberg
- Department of Biology, University of Miami, 1301 Memorial Drive, Coral Gables, FL, 33124, USA
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Mizokami Y, Noguchi K, Kojima M, Sakakibara H, Terashima I. Mesophyll conductance decreases in the wild type but not in an ABA-deficient mutant (aba1) of Nicotiana plumbaginifolia under drought conditions. PLANT, CELL & ENVIRONMENT 2015; 38:388-98. [PMID: 24995523 DOI: 10.1111/pce.12394] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 06/24/2014] [Accepted: 06/25/2014] [Indexed: 05/19/2023]
Abstract
Under drought conditions, leaf photosynthesis is limited by the supply of CO2 . Drought induces production of abscisic acid (ABA), and ABA decreases stomatal conductance (gs ). Previous papers reported that the drought stress also causes the decrease in mesophyll conductance (gm ). However, the relationships between ABA content and gm are unclear. We investigated the responses of gm to the leaf ABA content [(ABA)L ] using an ABA-deficient mutant, aba1, and the wild type (WT) of Nicotiana plumbaginifolia. We also measured leaf water potential (ΨL ) because leaf hydraulics may be related to gm . Under drought conditions, gm decreased with the increase in (ABA)L in WT, whereas both (ABA)L and gm were unchanged by the drought treatment in aba1. Exogenously applied ABA decreased gm in both WT and aba1 in a dose-dependent manner. ΨL in WT was decreased by the drought treatment to -0.7 MPa, whereas ΨL in aba1 was around -0.8 MPa even under the well-watered conditions and unchanged by the drought treatment. From these results, we conclude that the increase in (ABA)L is crucial for the decrease in gm under drought conditions. We discuss possible relationships between the decrease in gm and changes in the leaf hydraulics.
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Affiliation(s)
- Yusuke Mizokami
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan
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Théroux Rancourt G, Éthier G, Pepin S. Greater efficiency of water use in poplar clones having a delayed response of mesophyll conductance to drought. TREE PHYSIOLOGY 2015; 35:172-84. [PMID: 25721370 DOI: 10.1093/treephys/tpv006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Improvement of water use efficiency is a key objective to improve the sustainability of cultivated plants, especially fast growing species with high water consumption like poplar. It is well known that water use efficiency (WUE) varies considerably among poplar genotypes, and it was recently suggested that the use of the mesophyll-to-stomatal conductance ratio (gm/gs) would be an appropriate trait to improve WUE. The responses of 7-week-old cuttings of four hybrid poplar clones and one native Balsam poplar (Populus balsamifera L.) to a water stress-recovery cycle were examined to evaluate the relation between the gm/gs ratio and transpiration efficiency (TE), a leaf-level component of WUE. A contrasting gs response to water stress was observed among the five clones, from stomatal closure early on during soil drying up to limited closure in Balsam poplar. However in the hybrids, the decline in gm was consistently delayed by a few days compared with gs. Moreover, in the most water use-efficient hybrids, the recovery following rehydration occurred faster for gm than for gs. Thus, the delay in the response of gm to drought and its faster recovery upon rewatering increased the gm/gs of the hybrids and this ratio scaled positively with TE. Our results support the use of the gm/gs ratio to select genotypes with improved WUE, and the notion that breeding strategies focusing mainly on stomatal responses to soil drying should also look for a strong curvilinearity between net carbon assimilation rate and gs, the indication of a significant increase in gm/gs in the earlier stages of stomatal closure.
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Affiliation(s)
- Guillaume Théroux Rancourt
- Department of Plant Sciences, Horticultural Research Center, Université Laval, Québec, QC, Canada, G1V 0A6
| | - Gilbert Éthier
- Department of Plant Sciences, Horticultural Research Center, Université Laval, Québec, QC, Canada, G1V 0A6
| | - Steeve Pepin
- Department of Soil and Agri-Food Engineering, Horticultural Research Center, Université Laval, Québec, QC, Canada, G1V 0A6
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Loucos KE, Simonin KA, Song X, Barbour MM. Observed relationships between leaf H218O Péclet effective length and leaf hydraulic conductance reflect assumptions in Craig-Gordon model calculations. TREE PHYSIOLOGY 2015; 35:16-26. [PMID: 25576755 DOI: 10.1093/treephys/tpu110] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Stable oxygen isotope techniques may be a useful tool to investigate the pathways of water movement within leaves. However, implementation of such methods is limited due to uncertainty in the effective path length (L) for the Péclet effect in leaf water enrichment models. Previous studies have found relationships between L and physiological parameters such as transpiration rate (E) and leaf hydraulic conductance (k(leaf)) both within and between species. However, these studies relied on assumptions in their calculation of L, which were not directly tested. Eucalyptus paniculata Smith was used to evaluate the relationships between L, k(leaf) and E under differing water availability and a range of leaf temperatures. Coupled gas exchange and transpiration isotope measurements allowed previous assumptions to be directly tested. L was significantly and negatively related to both k(leaf) and E when the isotopic signature of water vapour was assumed to be in equilibrium with source water, was equivalent to the room vapour or equal to source water. However, the relationship between L and k(leaf) was non-significant when measured δ( 18)O of transpired vapour was used and disappeared entirely when non-steady-state leaves were excluded, and when evaporation site water was calculated from coupled gas exchange and transpiration isotope values. These results suggest that great care must be taken when calculating L, particularly regarding assumptions of isotopic steady state and δ( 18)O of vapour. Previous suggestions of changes in pathways for water movement as transpiration rate varied need to be reassessed in light of these observations.
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Affiliation(s)
- Karen E Loucos
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Rd, NSW 2570, Australia
| | - Kevin A Simonin
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Rd, NSW 2570, Australia Current address: Department of Biology, San Francisco State University, San Francisco, CA 94132, USA
| | - Xin Song
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Rd, NSW 2570, Australia
| | - Margaret M Barbour
- Centre for Carbon, Water and Food, Faculty of Agriculture and Environment, The University of Sydney, 380 Werombi Rd, NSW 2570, Australia
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Schmidt HL, Robins RJ, Werner RA. Multi-factorial in vivo stable isotope fractionation: causes, correlations, consequences and applications. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2015; 51:155-199. [PMID: 25894429 DOI: 10.1080/10256016.2015.1014355] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Many physical and chemical processes in living systems are accompanied by isotope fractionation on H, C, N, O and S. Although kinetic or thermodynamic isotope effects are always the basis, their in vivo manifestation is often modulated by secondary influences. These include metabolic branching events or metabolite channeling, metabolite pool sizes, reaction mechanisms, anatomical properties and compartmentation of plants and animals, and climatological or environmental conditions. In the present contribution, the fundamentals of isotope effects and their manifestation under in vivo conditions are outlined. The knowledge about and the understanding of these interferences provide a potent tool for the reconstruction of physiological events in plants and animals, their geographical origin, the history of bulk biomass and the biosynthesis of defined representatives. It allows the use of isotope characteristics of biomass for the elucidation of biochemical pathways and reaction mechanisms and for the reconstruction of climatic, physiological, ecological and environmental conditions during biosynthesis. Thus, it can be used for the origin and authenticity control of food, the study of ecosystems and animal physiology, the reconstruction of present and prehistoric nutrition chains and paleaoclimatological conditions. This is demonstrated by the outline of fundamental and application-orientated examples for all bio-elements. The aim of the review is to inform (advanced) students from various disciplines about the whole potential and the scope of stable isotope characteristics and fractionations and to provide them with a comprehensive introduction to the literature on fundamental aspects and applications.
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Affiliation(s)
- Hanns-Ludwig Schmidt
- a Lehrstuhl für Biologische Chemie , Technische Universität München , Freising-Weihenstephan, Germany
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Locke AM, Ort DR. Leaf hydraulic conductance declines in coordination with photosynthesis, transpiration and leaf water status as soybean leaves age regardless of soil moisture. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:6617-27. [PMID: 25281701 PMCID: PMC4246190 DOI: 10.1093/jxb/eru380] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Photosynthesis requires sufficient water transport through leaves for stomata to remain open as water transpires from the leaf, allowing CO2 to diffuse into the leaf. The leaf water needs of soybean change over time because of large microenvironment changes over their lifespan, as leaves mature in full sun at the top of the canopy and then become progressively shaded by younger leaves developing above. Leaf hydraulic conductance (K(leaf)), a measure of the leaf's water transport capacity, can often be linked to changes in microenvironment and transpiration demand. In this study, we tested the hypothesis that K(leaf) would decline in coordination with transpiration demand as soybean leaves matured and aged. Photosynthesis (A), stomatal conductance (g(s)) and leaf water potential (Ψ(leaf)) were also measured at various leaf ages with both field- and chamber-grown soybeans to assess transpiration demand. K(leaf) was found to decrease as soybean leaves aged from maturity to shading to senescence, and this decrease was strongly correlated with midday A. Decreases in K(leaf) were further correlated with decreases in g(s), although the relationship was not as strong as that with A. Separate experiments investigating the response of K(leaf) to drought demonstrated no acclimation of K(leaf) to drought conditions to protect against cavitation or loss of g(s) during drought and confirmed the effect of leaf age in K(leaf) observed in the field. These results suggest that the decline of leaf hydraulic conductance as leaves age keeps hydraulic supply in balance with demand without K(leaf)becoming limiting to transpiration water flux.
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Affiliation(s)
- Anna M Locke
- Department of Plant Biology, University of Illinois, Urbana, IL 61801, USA
| | - Donald R Ort
- Department of Plant Biology, University of Illinois, Urbana, IL 61801, USA Institute for Genomic Biology, University of Illinois, Urbana, IL 61801, USA Global Change and Photosynthesis Research Unit, Agricultural Research Service, United States Department of Agriculture, Urbana, IL 61801, USA
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Munksgaard NC, Cheesman AW, Wurster CM, Cernusak LA, Bird MI. Microwave extraction-isotope ratio infrared spectroscopy (ME-IRIS): a novel technique for rapid extraction and in-line analysis of δ18O and δ2H values of water in plants, soils and insects. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:2151-2161. [PMID: 25178719 DOI: 10.1002/rcm.7005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 07/28/2014] [Accepted: 07/29/2014] [Indexed: 06/03/2023]
Abstract
RATIONALE Traditionally, stable isotope analysis of plant and soil water has been a technically challenging, labour-intensive and time-consuming process. Here we describe a rapid single-step technique which combines Microwave Extraction with Isotope Ratio Infrared Spectroscopy (ME-IRIS). METHODS Plant, soil and insect water is extracted into a dry air stream by microwave irradiation within a sealed vessel. The water vapor thus produced is carried to a cooled condensation chamber, which controls the water vapor concentration and flow rate to the spectrometer. Integration of the isotope signals over the whole analytical cycle provides quantitative δ(18)O and δ(2) H values for the initial liquid water contained in the sample. Calibration is carried out by the analysis of water standards using the same apparatus. Analysis of leaf and soil water by cryogenic vacuum distillation and IRMS was used to validate the ME-IRIS data. RESULTS Comparison with data obtained by cryogenic distillation and IRMS shows that the new technique provides accurate water isotope data for leaves from a range of field-grown tropical plant species. However, two exotic nursery plants were found to suffer from spectral interferences from co-extracted organic compounds. The precision for extracted leaf, stem, soil and insect water was typically better than ±0.3 ‰ for δ(18)O and ±2 ‰ for δ(2) H values, and better than ±0.1 ‰ for δ(18)O and ±1 ‰ for δ(2) H values when analyzing water standards. The effects of sample size, microwave power and duration and sample-to-sample memory on isotope values were assessed. CONCLUSIONS ME-IRIS provides rapid and low-cost extraction and analysis of δ(18)O and δ(2) H values in plant, soil and insect water (≈10-15 min for samples yielding ≈ 0.3 mL of water). The technique can accommodate whole leaves of many plant species.
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Affiliation(s)
- Niels C Munksgaard
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Australia; School of Earth and Environmental Sciences and Centre for Tropical Environmental and Sustainability Science, James Cook University, Cairns, Australia
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Barbour MM, Song X. Do tree-ring stable isotope compositions faithfully record tree carbon/water dynamics? TREE PHYSIOLOGY 2014; 34:792-795. [PMID: 25117269 DOI: 10.1093/treephys/tpu064] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Affiliation(s)
- Margaret M Barbour
- Centre for Carbon, Water and Food, The University of Sydney, 380 Werombi Road, Brownlow Hill, NSW 2570, Australia;
| | - Xin Song
- Centre for Carbon, Water and Food, The University of Sydney, 380 Werombi Road, Brownlow Hill, NSW 2570, Australia
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Gessler A, Ferrio JP, Hommel R, Treydte K, Werner RA, Monson RK. Stable isotopes in tree rings: towards a mechanistic understanding of isotope fractionation and mixing processes from the leaves to the wood. TREE PHYSIOLOGY 2014; 34:796-818. [PMID: 24907466 DOI: 10.1093/treephys/tpu040] [Citation(s) in RCA: 172] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The mechanistic understanding of isotope fractionation processes is increasing but we still lack detailed knowledge of the processes that determine the isotopic composition of the tree-ring archive over the long term. Especially with regard to the path from leaf photosynthate production to wood formation, post-assimilation fractionations/processes might cause at least a partial decoupling between the leaf isotope signals that record processes such as stomatal conductance, transpiration and photosynthesis, and the wood or cellulose signals that are stored in the paleophysiological record. In this review, we start from the rather well understood processes at the leaf level such as photosynthetic carbon isotope fractionation, leaf water evaporative isotope enrichment and the issue of the isotopic composition of inorganic sources (CO2 and H2O), though we focus on the less explored 'downstream' processes related to metabolism and transport. We further summarize the roles of cellulose and lignin as important chemical constituents of wood, and the processes that determine the transfer of photosynthate (sucrose) and associated isotopic signals to wood production. We cover the broad topics of post-carboxylation carbon isotope fractionation and of the exchange of organic oxygen with water within the tree. In two case studies, we assess the transfer of carbon and oxygen isotopic signals from leaves to tree rings. Finally we address the issue of different temporal scales and link isotope fractionation at the shorter time scale for processes in the leaf to the isotopic ratio as recorded across longer time scales of the tree-ring archive.
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Affiliation(s)
- Arthur Gessler
- Institute for Landscape Biogeochemistry, Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalderstr. 84, 15374 Müncheberg, Germany Long-term Forest Ecosystem Research (LWF), Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Juan Pedro Ferrio
- Department of Crop and Forest Science-AGROTECNIO Center, University of Lleida, Avda Rovira Roure 191, 25198 Lleida, Spain
| | - Robert Hommel
- Institute for Landscape Biogeochemistry, Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalderstr. 84, 15374 Müncheberg, Germany
| | - Kerstin Treydte
- Research Unit Landscape Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Roland A Werner
- Institute of Agricultural Sciences, ETH Zurich, Universitaetsstrasse 2, 8092 Zurich, Switzerland
| | - Russell K Monson
- School of Natural Resources and the Environment and Laboratory for Tree Ring Research, University of Arizona, Tucson, AZ 85721, USA
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Marias DE, Meinzer FC, Woodruff DR, Shaw DC, Voelker SL, Brooks JR, Lachenbruch B, Falk K, McKay J. Impacts of dwarf mistletoe on the physiology of host Tsuga heterophylla trees as recorded in tree-ring C and O stable isotopes. TREE PHYSIOLOGY 2014; 34:595-607. [PMID: 24973917 DOI: 10.1093/treephys/tpu046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Dwarf mistletoes, obligate, parasitic plants with diminutive aerial shoots, have long-term effects on host tree water relations, hydraulic architecture and photosynthetic gas exchange and can eventually induce tree death. To investigate the long-term (1886-2010) impacts of dwarf mistletoe on the growth and gas exchange characteristics of host western hemlock, we compared the diameter growth and tree-ring cellulose stable carbon (C) and oxygen (O) isotope ratios (δ(13)Ccell, δ(18)Ocell) of heavily infected and uninfected trees. The relative basal area growth of infected trees was significantly greater than that of uninfected trees in 1886-90, but declined more rapidly in infected than uninfected trees through time and became significantly lower in infected than uninfected trees in 2006-10. Infected trees had significantly lower δ(13)Ccell and δ(18)Ocell than uninfected trees. Differences in δ(18)Ocell between infected and uninfected trees were unexpected given that stomatal conductance and environmental variables that were expected to influence the δ(18)O values of leaf water were similar for both groups. However, estimates of mesophyll conductance (gm) were significantly lower and estimates of effective path length for water movement (L) were significantly higher in leaves of infected trees, consistent with their lower values of δ(18)Ocell. This study reconstructs the long-term physiological responses of western hemlock to dwarf mistletoe infection. The long-term diameter growth and δ(13)Ccell trajectories suggested that infected trees were growing faster than uninfected trees prior to becoming infected and subsequently declined in growth and leaf-level photosynthetic capacity compared with uninfected trees as the dwarf mistletoe infection became severe. This study further points to limitations of the dual-isotope approach for identifying sources of variation in δ(13)Ccell and indicates that changes in leaf internal properties such as gm and L that affect δ(18)Ocell must be considered.
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Affiliation(s)
- Danielle E Marias
- Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, Corvallis, OR 97331, USA
| | - Frederick C Meinzer
- Pacific Northwest Research Station, USDA Forest Service, Corvallis, OR 97331, USA
| | - David R Woodruff
- Pacific Northwest Research Station, USDA Forest Service, Corvallis, OR 97331, USA
| | - David C Shaw
- Forest Engineering, Resources and Management, Oregon State University, 280 Peavy Hall, Corvallis, OR 97331, USA
| | - Steven L Voelker
- Biology Department, Southern Oregon University, 1250 Siskiyou Blvd, Ashland, OR 97520, USA
| | - J Renée Brooks
- Western Ecology Division, US EPANHEERL, Corvallis, OR 97331, USA
| | - Barbara Lachenbruch
- Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, Corvallis, OR 97331, USA
| | - Kristen Falk
- Forest Engineering, Resources and Management, Oregon State University, 280 Peavy Hall, Corvallis, OR 97331, USA
| | - Jennifer McKay
- College of Earth, Oceanic, and Atmospheric Sciences, Oregon State University, 104 CEOAS Administration Building, Corvallis, OR 97331, USA
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Sternberg LDSL, Manganiello LM. Stomatal pore size and density in mangrove leaves and artificial leaves: effects on leaf water isotopic enrichment during transpiration. FUNCTIONAL PLANT BIOLOGY : FPB 2014; 41:648-658. [PMID: 32481020 DOI: 10.1071/fp13235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 12/20/2013] [Indexed: 06/11/2023]
Abstract
We tested the hypothesis that the previously observed low isotopic enrichment of mangrove leaf water is caused by larger stomatal pores and lower densities compared with freshwater plants. First, we measured and compared pore size and density in mangroves, transitional and freshwater species in South Florida. We pooled this data with other reports encompassing 14 mangrove species and 134 freshwater species and tested for differences in pore size and density between mangroves and freshwater plants. Second, we built artificial leaves having different pore size and density and determined whether there were isotopic differences in their water after transpiration. Both the local survey and pooled data showed that mangrove leaves have significantly larger stomatal pores with lower densities compared with freshwater plants. Isotope enrichment of water from artificial leaves having larger less dense pores was lower than those having smaller and denser pores. Stomatal pore size and density has an effect on leaf water isotopic enrichment amongst other factors. Pore size and density probably affects key components of the Peclet ratio such as the distance advective flow of water must travel to the evaporative surface and the cross-sectional area of advective flow. These components, in turn, affect leaf water isotopic enrichment. Results from the artificial leaf experiment also mimic a recent finding that effective path length scales to the inverse of transpiration in real leaves. The implications of these findings further our understanding of leaf water isotope ratios and are important in applications of stable isotopes in the study of paleoclimate and atmospheric processes.
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Affiliation(s)
| | - Lynn M Manganiello
- Department of Biology, University of Miami, 1301 Memorial Drive, Coral Gables, FL 33146, USA
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Martins SCV, Galmés J, Cavatte PC, Pereira LF, Ventrella MC, DaMatta FM. Understanding the low photosynthetic rates of sun and shade coffee leaves: bridging the gap on the relative roles of hydraulic, diffusive and biochemical constraints to photosynthesis. PLoS One 2014; 9:e95571. [PMID: 24743509 PMCID: PMC3990704 DOI: 10.1371/journal.pone.0095571] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Accepted: 03/28/2014] [Indexed: 11/19/2022] Open
Abstract
It has long been held that the low photosynthetic rates (A) of coffee leaves are largely associated with diffusive constraints to photosynthesis. However, the relative limitations of the stomata and mesophyll to the overall diffusional constraints to photosynthesis, as well as the coordination of leaf hydraulics with photosynthetic limitations, remain to be fully elucidated in coffee. Whether the low actual A under ambient CO2 concentrations is associated with the kinetic properties of Rubisco and high (photo)respiration rates also remains elusive. Here, we provide a holistic analysis to understand the causes associated with low A by measuring a variety of key anatomical/hydraulic and photosynthetic traits in sun- and shade-grown coffee plants. We demonstrate that leaf hydraulic architecture imposes a major constraint on the maximisation of the photosynthetic gas exchange of coffee leaves. Regardless of the light treatments, A was mainly limited by stomatal factors followed by similar limitations associated with the mesophyll and biochemical constraints. No evidence of an inefficient Rubisco was found; rather, we propose that coffee Rubisco is well tuned for operating at low chloroplastic CO2 concentrations. Finally, we contend that large diffusive resistance should lead to large CO2 drawdown from the intercellular airspaces to the sites of carboxylation, thus favouring the occurrence of relatively high photorespiration rates, which ultimately leads to further limitations to A.
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Affiliation(s)
- Samuel C. V. Martins
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Jeroni Galmés
- Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears, Ctra. de Valldemossa, Palma, Balearic Islands, Spain
| | - Paulo C. Cavatte
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Lucas F. Pereira
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Marília C. Ventrella
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil
| | - Fábio M. DaMatta
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, MG, Brazil
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Chaumont F, Tyerman SD. Aquaporins: highly regulated channels controlling plant water relations. PLANT PHYSIOLOGY 2014; 164:1600-18. [PMID: 24449709 PMCID: PMC3982727 DOI: 10.1104/pp.113.233791] [Citation(s) in RCA: 366] [Impact Index Per Article: 36.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 01/19/2014] [Indexed: 05/18/2023]
Abstract
Plant growth and development are dependent on tight regulation of water movement. Water diffusion across cell membranes is facilitated by aquaporins that provide plants with the means to rapidly and reversibly modify water permeability. This is done by changing aquaporin density and activity in the membrane, including posttranslational modifications and protein interaction that act on their trafficking and gating. At the whole organ level aquaporins modify water conductance and gradients at key "gatekeeper" cell layers that impact on whole plant water flow and plant water potential. In this way they may act in concert with stomatal regulation to determine the degree of isohydry/anisohydry. Molecular, physiological, and biophysical approaches have demonstrated that variations in root and leaf hydraulic conductivity can be accounted for by aquaporins but this must be integrated with anatomical considerations. This Update integrates these data and emphasizes the central role played by aquaporins in regulating plant water relations.
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Affiliation(s)
| | - Stephen D. Tyerman
- Institut des Sciences de la Vie, Université catholique de Louvain, Croix du Sud 4–L7.07.14, B–1348 Louvain-la-Neuve, Belgium (F.C.); and
- Australian Research Council Centre of Excellence in Plant Energy Biology, Waite Research Institute, School of Agriculture, Food, and Wine, University of Adelaide, Waite Campus PMB 1, Glen Osmond, South Australia 5064, Australia (S.D.T.)
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Théroux-Rancourt G, Éthier G, Pepin S. Threshold response of mesophyll CO2 conductance to leaf hydraulics in highly transpiring hybrid poplar clones exposed to soil drying. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:741-53. [PMID: 24368507 PMCID: PMC3904724 DOI: 10.1093/jxb/ert436] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Mesophyll conductance (gm) has been shown to impose significant limitations to net CO2 assimilation (A) in various species during water stress. Net CO2 assimilation is also limited by stomatal conductance to water (gsw), both having been shown to co-vary with leaf hydraulic conductance (Kleaf). Lately, several studies have suggested a close functional link between Kleaf, gsw, and gm. However, such relationships could only be circumstantial since a recent study has shown that the response of gm to drought could merely be an artefactual consequence of a reduced intercellular CO2 mole fraction (Ci). Experiments were conducted on 8-week-old hybrid poplar cuttings to determine the relationship between Kleaf, gsw, and g m in clones of contrasting drought tolerance. It was hypothesized that changes in gsw and Kleaf in response to drought would not impact on gm over most of its range. The results show that Kleaf decreased in concert with g sw as drought proceeded, whereas gm measured at a normalized Ci remained relatively constant up to a g sw threshold of ~0.15 mol m(-2) s(-1). This delayed gm response prevented a substantial decline in A at the early stage of the drought, thereby enhancing water use efficiency. Reducing the stomatal limitation of droughted plants by diminishing the ambient CO2 concentration of the air did not modify gm or Kleaf. The relationship between gas exchange and leaf hydraulics was similar in both drought-tolerant and drought-sensitive clones despite their contrasting vulnerability to stem cavitation and stomatal response to soil drying. The results support the hypothesis of a partial hydraulic isolation of the mesophyll from the main transpiration pathway.
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Affiliation(s)
- Guillaume Théroux-Rancourt
- Department of Plant Sciences, Horticultural Research Center, Université Laval, 2480 boul. Hochelaga, Quebec, QC, G1V 0A6, Canada
| | - Gilbert Éthier
- Department of Plant Sciences, Horticultural Research Center, Université Laval, 2480 boul. Hochelaga, Quebec, QC, G1V 0A6, Canada
| | - Steeve Pepin
- Department of Soil and Agri-Food Engineering, Horticultural Research Center, Université Laval, 2480 boul. Hochelaga, Quebec, QC, G1V 0A6, Canada
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40
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Simonin KA, Roddy AB, Link P, Apodaca R, Tu KP, Hu J, Dawson TE, Barbour MM. Isotopic composition of transpiration and rates of change in leaf water isotopologue storage in response to environmental variables. PLANT, CELL & ENVIRONMENT 2013; 36:2190-206. [PMID: 23647101 DOI: 10.1111/pce.12129] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 04/18/2013] [Accepted: 04/22/2013] [Indexed: 05/27/2023]
Abstract
During daylight hours, the isotope composition of leaf water generally approximates steady-state leaf water isotope enrichment model predictions. However, until very recently there was little direct confirmation that isotopic steady-state (ISS) transpiration in fact exists. Using isotope ratio infrared spectroscopy (IRIS) and leaf gas exchange systems we evaluated the isotope composition of transpiration and the rate of change in leaf water isotopologue storage (isostorage) when leaves were exposed to variable environments. In doing so, we developed a method for controlling the absolute humidity entering the gas exchange cuvette for a wide range of concentrations without changing the isotope composition of water vapour. The measurement system allowed estimation of (18)O enrichment both at the evaporation site and for bulk leaf water, in the steady state and the non-steady state. We show that non-steady-state effects dominate the transpiration isoflux even when leaves are at physiological steady state. Our results suggest that a variable environment likely prevents ISS transpiration from being achieved and that this effect may be exacerbated by lengthy leaf water turnover times due to high leaf water contents.
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Affiliation(s)
- Kevin A Simonin
- Faculty of Agriculture and Environment, University of Sydney, Sydney, NSW, 2570, Australia
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41
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Cano FJ, Sánchez-Gómez D, Rodríguez-Calcerrada J, Warren CR, Gil L, Aranda I. Effects of drought on mesophyll conductance and photosynthetic limitations at different tree canopy layers. PLANT, CELL & ENVIRONMENT 2013; 36:1961-80. [PMID: 23527762 DOI: 10.1111/pce.12103] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 03/12/2013] [Accepted: 03/14/2013] [Indexed: 05/24/2023]
Abstract
In recent years, many studies have focused on the limiting role of mesophyll conductance (gm ) to photosynthesis (An ) under water stress, but no studies have examined the effect of drought on gm through the forest canopy. We investigated limitations to An on leaves at different heights in a mixed adult stand of sessile oak (Quercus petraea) and beech (Fagus sylvatica) trees during a moderately dry summer. Moderate drought decreased An of top and lowest beech canopy leaves much more than in leaves located in the mid canopy; whereas in oak, An of the lower canopy was decreased more than in sunlit leaves. The decrease of An was probably not due to leaf-level biochemistry given that VCmax was generally unaffected by drought. The reduction in An was instead associated with reduction in stomatal and mesophyll conductances. Drought-induced increases in stomatal limitations were largest in leaves from the top canopy, whereas drought-induced increases in mesophyll limitations were largest in leaves from the lowest canopy. Sensitivity analysis highlighted the need to decompose the canopy into different leaf layers and to incorporate the limitation imposed by gm when assessing the impact of drought on the gas exchange of tree canopies.
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Affiliation(s)
- F Javier Cano
- Unidad Docente de Anatomía, Fisiología y Genética Forestal, E.T.S.I. Montes, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria s/n, 28040, Madrid, Spain
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42
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Sack L, Scoffoni C, John GP, Poorter H, Mason CM, Mendez-Alonzo R, Donovan LA. How do leaf veins influence the worldwide leaf economic spectrum? Review and synthesis. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:4053-80. [PMID: 24123455 DOI: 10.1093/jxb/ert316] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Leaf vein traits are implicated in the determination of gas exchange rates and plant performance. These traits are increasingly considered as causal factors affecting the 'leaf economic spectrum' (LES), which includes the light-saturated rate of photosynthesis, dark respiration, foliar nitrogen concentration, leaf dry mass per area (LMA) and leaf longevity. This article reviews the support for two contrasting hypotheses regarding a key vein trait, vein length per unit leaf area (VLA). Recently, Blonder et al. (2011, 2013) proposed that vein traits, including VLA, can be described as the 'origin' of the LES by structurally determining LMA and leaf thickness, and thereby vein traits would predict LES traits according to specific equations. Careful re-examination of leaf anatomy, published datasets, and a newly compiled global database for diverse species did not support the 'vein origin' hypothesis, and moreover showed that the apparent power of those equations to predict LES traits arose from circularity. This review provides a 'flux trait network' hypothesis for the effects of vein traits on the LES and on plant performance, based on a synthesis of the previous literature. According to this hypothesis, VLA, while virtually independent of LMA, strongly influences hydraulic conductance, and thus stomatal conductance and photosynthetic rate. We also review (i) the specific physiological roles of VLA; (ii) the role of leaf major veins in influencing LES traits; and (iii) the role of VLA in determining photosynthetic rate per leaf dry mass and plant relative growth rate. A clear understanding of leaf vein traits provides a new perspective on plant function independently of the LES and can enhance the ability to explain and predict whole plant performance under dynamic conditions, with applications towards breeding improved crop varieties.
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Affiliation(s)
- Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA 90095, USA
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Gessler A, Brandes E, Keitel C, Boda S, Kayler ZE, Granier A, Barbour M, Farquhar GD, Treydte K. The oxygen isotope enrichment of leaf-exported assimilates--does it always reflect lamina leaf water enrichment? THE NEW PHYTOLOGIST 2013; 200:144-157. [PMID: 23763637 PMCID: PMC3902987 DOI: 10.1111/nph.12359] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 05/09/2013] [Indexed: 05/12/2023]
Abstract
The oxygen stable isotope composition of plant organic matter (OM) (particularly of wood and cellulose in the tree ring archive) is valuable in studies of plant-climate interaction, but there is a lack of information on the transfer of the isotope signal from the leaf to heterotrophic tissues. We studied the oxygen isotopic composition and its enrichment above source water of leaf water over diel courses in five tree species covering a broad range of life forms. We tracked the transfer of the isotopic signal to leaf water-soluble OM and further to phloem-transported OM. Observed leaf water evaporative enrichment was consistent with values predicted from mechanistic models taking into account nonsteady-state conditions. While leaf water-soluble OM showed the expected (18)O enrichment in all species, phloem sugars were less enriched than expected from leaf water enrichment in Scots pine (Pinus sylvestris), European larch (Larix decidua) and Alpine ash (Eucalyptus delegatensis). Oxygen atom exchange with nonenriched water during phloem loading and transport, as well as a significant contribution of assimilates from bark photosynthesis, can explain these phloem (18)O enrichment patterns. Our results indicate species-specific uncoupling between the leaf water and the OM oxygen isotope signal, which is important for the interpretation of tree ring data.
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Affiliation(s)
- Arthur Gessler
- Leibniz Centre for Agricultural Landscape Research, Institute for Landscape BiogeochemistryEberswalderstr. 84, 15374, Müncheberg, Germany
- INRA, UMR 1137 Ecologie et Ecophysiologie Forestières INRA/Université de Lorraine54280, Champenoux, France
- Research School of Biology, Australian National UniversityBuilding 46, Acton, ACT, 0200, Autralia
| | - Elke Brandes
- INRA, UMR 1137 Ecologie et Ecophysiologie Forestières INRA/Université de Lorraine54280, Champenoux, France
| | - Claudia Keitel
- Research School of Biology, Australian National UniversityBuilding 46, Acton, ACT, 0200, Autralia
- Faculty of Agriculture and Environment, University of SydneyPrivate Bag 4011, Narellan, NSW, 2567, Australia
| | - Sonja Boda
- Swiss Federal Research Institute WSL, Research Unit Landscape DynamicsZürcherstrasse 111, CH-8903, Birmensdorf, Switzerland
| | - Zachary E Kayler
- Leibniz Centre for Agricultural Landscape Research, Institute for Landscape BiogeochemistryEberswalderstr. 84, 15374, Müncheberg, Germany
| | - André Granier
- INRA, UMR 1137 Ecologie et Ecophysiologie Forestières INRA/Université de Lorraine54280, Champenoux, France
| | - Margaret Barbour
- Faculty of Agriculture and Environment, University of SydneyPrivate Bag 4011, Narellan, NSW, 2567, Australia
| | - Graham D Farquhar
- Research School of Biology, Australian National UniversityBuilding 46, Acton, ACT, 0200, Autralia
| | - Kerstin Treydte
- Swiss Federal Research Institute WSL, Research Unit Landscape DynamicsZürcherstrasse 111, CH-8903, Birmensdorf, Switzerland
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Flexas J, Scoffoni C, Gago J, Sack L. Leaf mesophyll conductance and leaf hydraulic conductance: an introduction to their measurement and coordination. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:3965-81. [PMID: 24123453 DOI: 10.1093/jxb/ert319] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Two highly contrasting variables summarizing the efficiency of transport of materials within the leaf are recognized as playing central roles in determining gas exchange and plant performance. This paper summarizes current approaches for the measurement of mesophyll conductance to CO2 (g m) and leaf hydraulic conductance (K leaf) and addresses the physiological integration of these parameters. First, the most common methods to determine g m and K leaf are summarized. Next, novel data compilation is analysed, which indicates that, across diverse species, g m is strongly linked with gas exchange parameters such as net CO2 assimilation (A area) and stomatal conductance (g s), and with K leaf, independently of leaf vein length per leaf area. Based on their parallel responses to a number of environmental variables, this review proposes that g m is linked to the outside-xylem but not to the xylem component of K leaf. Further, a mechanistic hypothesis is proposed to explain the interactions among all these and other physiological parameters. Finally, the possibility of estimating g m based on this hypothesis was tested using a regression analysis and a neurofuzzy logic approach. These approaches enabled the estimation of g m of given species from K leaf and leaf mass per area, providing a higher predictive power than from either parameter alone. The possibility of estimating g m from measured K leaf or vice-versa would result in a rapid increase in available data. Studies in which g m, K leaf, and leaf mass per area are simultaneously determined are needed in order to confirm and strengthen predictive and explanatory models for these parameters and importantly improve resolution of the integrated hydraulic-stomatal-photosynthetic system.
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Affiliation(s)
- Jaume Flexas
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07121 Palma de Mallorca, Illes Balears, Spain
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45
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Rosado BHP, De Mattos EA, Sternberg LDSL. Are leaf physiological traits related to leaf water isotopic enrichment in restinga woody species? AN ACAD BRAS CIENC 2013; 85:1035-46. [PMID: 24068091 DOI: 10.1590/s0001-37652013005000051] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 08/23/2012] [Indexed: 11/22/2022] Open
Abstract
During plant-transpiration, water molecules having the lighter stable isotopes of oxygen and hydrogen evaporate and diffuse at a faster rate through the stomata than molecules having the heavier isotopes, which cause isotopic enrichment of leaf water. Although previous models have assumed that leaf water is well-mixed and isotopically uniform, non-uniform stomatal closure, promoting different enrichments between cells, and different pools of water within leaves, due to morpho-physiological traits, might lead to inaccuracies in isotopic models predicting leaf water enrichment. We evaluate the role of leaf morpho-physiological traits on leaf water isotopic enrichment in woody species occurring in a coastal vegetation of Brazil known as restinga. Hydrogen and oxygen stable isotope values of soil, plant stem and leaf water and leaf traits were measured in six species from restinga vegetation during a drought and a wet period. Leaf water isotopic enrichment relative to stem water was more homogeneous among species during the drought in contrast to the wet period suggesting convergent responses to deal to temporal heterogeneity in water availability. Average leaf water isotopic enrichment relative to stem water during the drought period was highly correlated with relative apoplastic water content. We discuss this observation in the context of current models of leaf water isotopic enrichment as a function of the Péclet effect. We suggest that future studies should include relative apoplastic water content in isotopic models.
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Affiliation(s)
- Bruno H P Rosado
- Departamento de Ecologia, IB, CCS, Universidade Federal do Rio de Janeiro, Av. Brigadeiro Trompowski, s/n, C.P. 68020, 21941-970 Rio de Janeiro, RJ, Brasil.
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46
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Song X, Barbour MM, Farquhar GD, Vann DR, Helliker BR. Transpiration rate relates to within- and across-species variations in effective path length in a leaf water model of oxygen isotope enrichment. PLANT, CELL & ENVIRONMENT 2013; 36:1338-1351. [PMID: 23305086 DOI: 10.1111/pce.12063] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 12/15/2012] [Accepted: 12/17/2012] [Indexed: 06/01/2023]
Abstract
Stable oxygen isotope ratio of leaf water (δ(18)O(L)) yields valuable information on many aspects of plant-environment interactions. However, current understanding of the mechanistic controls on δ(18)O(L) does not provide complete characterization of effective path length (L) of the Péclet effect,--a key component of the leaf water model. In this study, we collected diurnal and seasonal series of leaf water enrichment and estimated L in six field-grown angiosperm and gymnosperm tree species. Our results suggest a pivotal role of leaf transpiration rate (E) in driving both within- and across-species variations in L. Our observation of the common presence of an inverse scaling of L with E in the different species therefore cautions against (1) the conventional treatment of L as a species-specific constant in leaf water or cellulose isotope (δ(18)O(p)) modelling; and (2) the use of δ(18)O(p) as a proxy for gs or E under low E conditions. Further, we show that incorporation of a multi-species L-E scaling into the leaf water model has the potential to both improve the prediction accuracy and simplify parameterization of the model when compared with the conventional approach. This has important implications for future modelling of oxygen isotope ratios.
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Affiliation(s)
- Xin Song
- Department of Biology, University of Pennsylvania, 433 S University Ave., Philadelphia, PA 19104, USA.
| | - Margaret M Barbour
- Landcare Research, PO Box 40, Lincoln, 7640, New Zealand
- Faculty of Agriculture and Environment, University of Sydney, Private Bag 4110, Narellan, NSW, 2567, Australia
| | - Graham D Farquhar
- Research School of Biology, The Australian National University, Canberra, ACT, 0200, Australia
| | - David R Vann
- Department of Biology, University of Pennsylvania, 433 S. University Ave., Philadelphia, PA, 19104, USA
| | - Brent R Helliker
- Department of Biology, University of Pennsylvania, 433 S. University Ave., Philadelphia, PA, 19104, USA
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47
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Cernusak LA, Kahmen A. The multifaceted relationship between leaf water (18)O enrichment and transpiration rate. PLANT, CELL & ENVIRONMENT 2013; 36:1239-1241. [PMID: 23421713 DOI: 10.1111/pce.12081] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 02/12/2013] [Indexed: 06/01/2023]
Affiliation(s)
- Lucas A Cernusak
- Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia.
| | - Ansgar Kahmen
- Institute of Agricultural Sciences, ETH Zurich, Zurich, 8092, Switzerland
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48
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Pou A, Medrano H, Flexas J, Tyerman SD. A putative role for TIP and PIP aquaporins in dynamics of leaf hydraulic and stomatal conductances in grapevine under water stress and re-watering. PLANT, CELL & ENVIRONMENT 2013; 36:828-43. [PMID: 23046275 DOI: 10.1111/pce.12019] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We examined the role of aquaporins (AQPs) in regulating leaf hydraulic conductance (Kleaf ) in Vitis vinifera L. (cv Chardonnay) by studying effects of AQP inhibitors, and AQP gene expression during water stress (WS) and recovery (REC). Kleaf was measured after 3 h of petiole perfusion with different solutions and to introduce inhibitors. The addition of 0.1 mm HgCl2 to 15 mm KCl reduced Kleaf compared with perfusion in 15 mM KNO3 or KCl, and these solutions were used for leaves from control, WS and REC plants. Perfusion for 3 h did not significantly alter stomatal conductance (gs ) though expression of VvTIP1;1 was increased. WS decreased Kleaf by about 30% and was correlated with gs . The expression of VvTIP2;1 and VvPIP2;1 correlated with Kleaf , and VvTIP2;1 was highly correlated with gs . There was no association between the expression of particular AQPs during WS and REC and inhibition of Kleaf by HgCl2 ; however, HgCl2 treatment itself increased expression of VvPIP2;3 and decreased expression of VvPIP2;1. Inhibition by HgCl2 of Kleaf only at early stages of WS and then after REC suggested that apoplasmic pathways become more important during WS. This was confirmed using fluorescent dyes confined to apoplasm or preferentially accumulated in symplasm.
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Affiliation(s)
- Alicia Pou
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide, Glen Osmond, SA 5064, Australia
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49
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Peguero-Pina JJ, Flexas J, Galmés J, Niinemets U, Sancho-Knapik D, Barredo G, Villarroya D, Gil-Pelegrín E. Leaf anatomical properties in relation to differences in mesophyll conductance to CO(2) and photosynthesis in two related Mediterranean Abies species. PLANT, CELL & ENVIRONMENT 2012; 35:2121-9. [PMID: 22594917 DOI: 10.1111/j.1365-3040.2012.02540.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Abies alba and Abies pinsapo are closely related species with the same ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco) large subunit (rbcL) but contrasting hydraulic traits and mesophyll structure occurring in the Iberian Peninsula under contrasting conditions. As photosynthesis and hydraulic capacities often co-scale, we hypothesize that these species differ in mesophyll conductance to CO(2) (g(m) ). g(m) and key anatomical traits were measured in both species. Drought-adapted population of A. pinsapo has higher photosynthesis than the more mesic population of A. alba, in agreement with its higher hydraulic capacity. However, A. alba exhibits the largest stomatal conductance (g(s) ), and so water use efficiency (WUE) is much higher in A. pinsapo. The differences in photosynthesis were explained by differences in g(m) , indicating a correlation between hydraulic capacity and g(m) . We report a case where g(m) is the main factor limiting photosynthesis in one species (A. alba) when compared with the other one (A. pinsapo). The results also highlight the discrepancy between g(m) estimates based on anatomical measurements and those based on gas exchange methods, probably due to the very large resistance exerted by cell walls and the stroma in both species. Thus, the cell wall and chloroplast properties in relation to CO(2) diffusion constitute a near-future research priority.
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Affiliation(s)
- José Javier Peguero-Pina
- Grup de Recerca en Biologia de les Plantes en Condicions Mediterrànies, Departament de Biologia, Universitat de les Illes Balears, Carretera de Valldemossa, km 7.5, 07071, Palma de Mallorca, Balears, Spain
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50
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Sharkey TD. Virtual special issue on [corrected] mesophyll conductance: constraint on carbon acquisition by C3 plants. PLANT, CELL & ENVIRONMENT 2012; 35:1881-1883. [PMID: 23043351 DOI: 10.1111/pce.12012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
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