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Gimeno TE, Campany CE, Drake JE, Barton CVM, Tjoelker MG, Ubierna N, Marshall JD. Whole-tree mesophyll conductance reconciles isotopic and gas-exchange estimates of water-use efficiency. THE NEW PHYTOLOGIST 2021; 229:2535-2547. [PMID: 33217000 DOI: 10.1111/nph.17088] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 11/07/2020] [Indexed: 06/11/2023]
Abstract
Photosynthetic water-use efficiency (WUE) describes the link between terrestrial carbon (C) and water cycles. Estimates of intrinsic WUE (iWUE) from gas exchange and C isotopic composition (δ13 C) differ due to an internal conductance in the leaf mesophyll (gm ) that is variable and seldom computed. We present the first direct estimates of whole-tree gm , together with iWUE from whole-tree gas exchange and δ13 C of the phloem (δ13 Cph ). We measured gas exchange, online 13 C-discrimination, and δ13 Cph monthly throughout spring, summer, and autumn in Eucalyptus tereticornis grown in large whole-tree chambers. Six trees were grown at ambient temperatures and six at a 3°C warmer air temperature; a late-summer drought was also imposed. Drought reduced whole-tree gm . Warming had few direct effects, but amplified drought-induced reductions in whole-tree gm . Whole-tree gm was similar to leaf gm for these same trees. iWUE estimates from δ13 Cph agreed with iWUE from gas exchange, but only after incorporating gm . δ13 Cph was also correlated with whole-tree 13 C-discrimination, but offset by -2.5 ± 0.7‰, presumably due to post-photosynthetic fractionations. We conclude that δ13 Cph is a good proxy for whole-tree iWUE, with the caveats that post-photosynthetic fractionations and intrinsic variability of gm should be incorporated to provide reliable estimates of this trait in response to abiotic stress.
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Affiliation(s)
- Teresa E Gimeno
- Basque Centre for Climate Change (BC3), Leioa, 48940, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, 48008, Spain
| | - Courtney E Campany
- Department of Biology, Shepherd University, Shepherdstown, WV, 25443, USA
| | - John E Drake
- Forest and Natural Resources Management, SUNY-ESF, Syracuse, NY, 132110, USA
| | - Craig V M Barton
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Mark G Tjoelker
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Nerea Ubierna
- Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
| | - John D Marshall
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), Skogsmarksgränd 17, 907 36, Umeå, Sweden
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Vernay A, Tian X, Chi J, Linder S, Mäkelä A, Oren R, Peichl M, Stangl ZR, Tor-Ngern P, Marshall JD. Estimating canopy gross primary production by combining phloem stable isotopes with canopy and mesophyll conductances. PLANT, CELL & ENVIRONMENT 2020; 43:2124-2142. [PMID: 32596814 DOI: 10.1111/pce.13835] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 06/21/2020] [Accepted: 06/22/2020] [Indexed: 06/11/2023]
Abstract
Gross primary production (GPP) is a key component of the forest carbon cycle. However, our knowledge of GPP at the stand scale remains uncertain, because estimates derived from eddy covariance (EC) rely on semi-empirical modelling and the assumptions of the EC technique are sometimes not fully met. We propose using the sap flux/isotope method as an alternative way to estimate canopy GPP, termed GPPiso/SF , at the stand scale and at daily resolution. It is based on canopy conductance inferred from sap flux and intrinsic water-use efficiency estimated from the stable carbon isotope composition of phloem contents. The GPPiso/SF estimate was further corrected for seasonal variations in photosynthetic capacity and mesophyll conductance. We compared our estimate of GPPiso/SF to the GPP derived from PRELES, a model parameterized with EC data. The comparisons were performed in a highly instrumented, boreal Scots pine forest in northern Sweden, including a nitrogen fertilized and a reference plot. The resulting annual and daily GPPiso/SF estimates agreed well with PRELES, in the fertilized plot and the reference plot. We discuss the GPPiso/SF method as an alternative which can be widely applied without terrain restrictions, where the assumptions of EC are not met.
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Affiliation(s)
- Antoine Vernay
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Xianglin Tian
- Department of Forest Sciences, University of Helsinki, Helsinki, Finland
| | - Jinshu Chi
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Sune Linder
- Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Annikki Mäkelä
- Department of Forest Sciences, University of Helsinki, Helsinki, Finland
| | - Ram Oren
- Department of Forest Sciences, University of Helsinki, Helsinki, Finland
- Division of Environmental Science & Policy, Nicholas School of the Environment, Duke University, Durham, North Carolina, USA
- Department of Civil & Environmental Engineering, Pratt School of Engineering, Duke University, Durham, North Carolina, USA
| | - Matthias Peichl
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Zsofia R Stangl
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Pantana Tor-Ngern
- Department of Environmental Science, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
- Environment, Health and Social Data Analytics Research Group, Chulalongkorn University, Bangkok, Thailand
| | - John D Marshall
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
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Bögelein R, Lehmann MM, Thomas FM. Differences in carbon isotope leaf-to-phloem fractionation and mixing patterns along a vertical gradient in mature European beech and Douglas fir. THE NEW PHYTOLOGIST 2019; 222:1803-1815. [PMID: 30740705 DOI: 10.1111/nph.15735] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 02/03/2019] [Indexed: 05/13/2023]
Abstract
While photosynthetic isotope discrimination is well understood, the postphotosynthetic and transport-related fractionation mechanisms that influence phloem and subsequently tree ring δ13 C are less investigated and may vary among species. We studied the seasonal and diel courses of leaf-to-phloem δ13 C differences of water-soluble organic matter (WSOM) in vertical crown gradients and followed the assimilate transport via the branches to the trunk phloem at breast height in European beech (Fagus sylvatica) and Douglas fir (Pseudotsuga menziesii). δ13 C of individual sugars and cyclitols from a subsample was determined by compound-specific isotope analysis. In beech, leaf-to-phloem δ13 C differences in WSOM increased with height and were partly caused by biochemical isotope fractionation between leaf compounds. 13 C-Enrichment of phloem sugars relative to leaf sucrose implies an additional isotope fractionation mechanism related to leaf assimilate export. In Douglas fir, leaf-to-phloem δ13 C differences were much smaller and isotopically invariant pinitol strongly influenced leaf and phloem WSOM. Trunk phloem WSOM at breast height reflected canopy-integrated δ13 C in beech but not in Douglas fir. Our results demonstrate that leaf-to-phloem isotope fractionation and δ13 C mixing patterns along vertical gradients can differ between tree species. These effects have to be considered for functional interpretations of trunk phloem and tree ring δ13 C.
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Affiliation(s)
- Rebekka Bögelein
- Faculty of Regional and Environmental Sciences - Geobotany, University of Trier, Behringstraße 21, Trier, 54296, Germany
| | - Marco M Lehmann
- Forest Dynamics, Swiss Federal Institute WSL Birmensdorf, Zuercherstrasse 111, Birmensdorf, 8903, Switzerland
| | - Frank M Thomas
- Faculty of Regional and Environmental Sciences - Geobotany, University of Trier, Behringstraße 21, Trier, 54296, Germany
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Lehmann MM, Wegener F, Werner RA, Werner C. Diel variations in carbon isotopic composition and concentration of organic acids and their impact on plant dark respiration in different species. PLANT BIOLOGY (STUTTGART, GERMANY) 2016; 18:776-84. [PMID: 27086877 DOI: 10.1111/plb.12464] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 04/13/2016] [Indexed: 05/19/2023]
Abstract
Leaf respiration in the dark and its C isotopic composition (δ(13) CR ) contain information about internal metabolic processes and respiratory substrates. δ(13) CR is known to be less negative compared to potential respiratory substrates, in particular shortly after darkening during light enhanced dark respiration (LEDR). This phenomenon might be driven by respiration of accumulated (13) C-enriched organic acids, however, studies simultaneously measuring δ(13) CR during LEDR and potential respiratory substrates are rare. We determined δ(13) CR and respiration rates (R) during LEDR, as well as δ(13) C and concentrations of potential respiratory substrates using compound-specific isotope analyses. The measurements were conducted throughout the diel cycle in several plant species under different environmental conditions. δ(13) CR and R patterns during LEDR were strongly species-specific and showed an initial peak, which was followed by a progressive decrease in both values. The species-specific differences in δ(13) CR and R during LEDR may be partially explained by the isotopic composition of organic acids (e.g., oxalate, isocitrate, quinate, shikimate, malate), which were (13) C-enriched compared to other respiratory substrates (e.g., sugars and amino acids). However, the diel variations in both δ(13) C and concentrations of the organic acids were generally low. Thus, additional factors such as the heterogeneous isotope distribution in organic acids and the relative contribution of the organic acids to respiration are required to explain the strong (13) C enrichment in leaf dark-respired CO2 .
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Affiliation(s)
- M M Lehmann
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), Villigen, Switzerland
- Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - F Wegener
- Ecosystem Physiology, University Freiburg, Freiburg, Germany
| | - R A Werner
- Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - C Werner
- Ecosystem Physiology, University Freiburg, Freiburg, Germany
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Lehmann MM, Wegener F, Barthel M, Maurino VG, Siegwolf RTW, Buchmann N, Werner C, Werner RA. Metabolic Fate of the Carboxyl Groups of Malate and Pyruvate and their Influence on δ(13)C of Leaf-Respired CO2 during Light Enhanced Dark Respiration. FRONTIERS IN PLANT SCIENCE 2016; 7:739. [PMID: 27375626 PMCID: PMC4891945 DOI: 10.3389/fpls.2016.00739] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/13/2016] [Indexed: 05/03/2023]
Abstract
The enhanced CO2 release of illuminated leaves transferred into darkness, termed "light enhanced dark respiration (LEDR)", is often associated with an increase in the carbon isotope ratio of the respired CO2 (δ(13)CLEDR). The latter has been hypothesized to result from different respiratory substrates and decarboxylation reactions in various metabolic pathways, which are poorly understood so far. To provide a better insight into the underlying metabolic processes of δ(13)CLEDR, we fed position-specific (13)C-labeled malate and pyruvate via the xylem stream to leaves of species with high and low δ(13)CLEDR values (Halimium halimifolium and Oxalis triangularis, respectively). During respective label application, we determined label-derived leaf (13)CO2 respiration using laser spectroscopy and the (13)C allocation to metabolic fractions during light-dark transitions. Our results clearly show that both carboxyl groups (C-1 and C-4 position) of malate similarly influence respiration and metabolic fractions in both species, indicating possible isotope randomization of the carboxyl groups of malate by the fumarase reaction. While C-2 position of pyruvate was only weakly respired, the species-specific difference in natural δ(13)CLEDR patterns were best reflected by the (13)CO2 respiration patterns of the C-1 position of pyruvate. Furthermore, (13)C label from malate and pyruvate were mainly allocated to amino and organic acid fractions in both species and only little to sugar and lipid fractions. In summary, our results suggest that respiration of both carboxyl groups of malate (via fumarase) by tricarboxylic acid cycle reactions or by NAD-malic enzyme influences δ(13)CLEDR. The latter supplies the pyruvate dehydrogenase reaction, which in turn determines natural δ(13)CLEDR pattern by releasing the C-1 position of pyruvate.
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Affiliation(s)
- Marco M. Lehmann
- Laboratory of Atmospheric Chemistry, Paul Scherrer InstituteVilligen, Switzerland
- Institute of Agricultural Sciences, ETH ZurichZurich, Switzerland
| | | | - Matti Barthel
- Institute of Agricultural Sciences, ETH ZurichZurich, Switzerland
| | - Veronica G. Maurino
- Plant Molecular Physiology and Biotechnology Group, Institute of Developmental and Molecular Biology of Plants, Heinrich Heine University and Cluster of Excellence on Plant Sciences (CEPLAS)Düsseldorf, Germany
| | - Rolf T. W. Siegwolf
- Laboratory of Atmospheric Chemistry, Paul Scherrer InstituteVilligen, Switzerland
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH ZurichZurich, Switzerland
| | | | - Roland A. Werner
- Institute of Agricultural Sciences, ETH ZurichZurich, Switzerland
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Lehmann MM, Rinne KT, Blessing C, Siegwolf RTW, Buchmann N, Werner RA. Malate as a key carbon source of leaf dark-respired CO2 across different environmental conditions in potato plants. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:5769-81. [PMID: 26139821 PMCID: PMC4566975 DOI: 10.1093/jxb/erv279] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Dissimilation of carbon sources during plant respiration in support of metabolic processes results in the continuous release of CO2. The carbon isotopic composition of leaf dark-respired CO2 (i.e. δ (13) C R ) shows daily enrichments up to 14.8‰ under different environmental conditions. However, the reasons for this (13)C enrichment in leaf dark-respired CO2 are not fully understood, since daily changes in δ(13)C of putative leaf respiratory carbon sources (δ (13) C RS ) are not yet clear. Thus, we exposed potato plants (Solanum tuberosum) to different temperature and soil moisture treatments. We determined δ (13) C R with an in-tube incubation technique and δ (13) C RS with compound-specific isotope analysis during a daily cycle. The highest δ (13) C RS values were found in the organic acid malate under different environmental conditions, showing less negative values compared to δ (13) C R (up to 5.2‰) and compared to δ (13) C RS of soluble carbohydrates, citrate and starch (up to 8.8‰). Moreover, linear relationships between δ (13) C R and δ (13) C RS among different putative carbon sources were strongest for malate during daytime (r(2)=0.69, P≤0.001) and nighttime (r(2)=0.36, P≤0.001) under all environmental conditions. A multiple linear regression analysis revealed δ (13) C RS of malate as the most important carbon source influencing δ (13) C R . Thus, our results strongly indicate malate as a key carbon source of (13)C enriched dark-respired CO2 in potato plants, probably driven by an anapleurotic flux replenishing intermediates of the Krebs cycle.
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Affiliation(s)
- Marco M Lehmann
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), CH-5232 Villigen, Switzerland Institute of Agricultural Sciences, ETH Zurich, Universitaetsstr. 2, CH-8092 Zurich, Switzerland
| | - Katja T Rinne
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), CH-5232 Villigen, Switzerland
| | - Carola Blessing
- Institute of Agricultural Sciences, ETH Zurich, Universitaetsstr. 2, CH-8092 Zurich, Switzerland
| | - Rolf T W Siegwolf
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), CH-5232 Villigen, Switzerland
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH Zurich, Universitaetsstr. 2, CH-8092 Zurich, Switzerland
| | - Roland A Werner
- Institute of Agricultural Sciences, ETH Zurich, Universitaetsstr. 2, CH-8092 Zurich, Switzerland
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Wegener F, Beyschlag W, Werner C. Dynamic carbon allocation into source and sink tissues determine within-plant differences in carbon isotope ratios. FUNCTIONAL PLANT BIOLOGY : FPB 2015; 42:620-629. [PMID: 32480706 DOI: 10.1071/fp14152] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 03/10/2015] [Indexed: 05/28/2023]
Abstract
Organs of C3 plants differ in their C isotopic signature (δ13C). In general, leaves are 13C-depleted relative to other organs. To investigate the development of spatial δ13C patterns, we induced different C allocation strategies by reducing light and nutrient availability for 12 months in the Mediterranean shrub Halimium halimifolium L. We measured morphological and physiological traits and the spatial δ13C variation among seven tissue classes during the experiment. A reduction of light (Low-L treatment) increased aboveground C allocation, plant height and specific leaf area. Reduced nutrient availability (Low-N treatment) enhanced C allocation into fine roots and reduced the spatial δ13C variation. In contrast, control and Low-L plants with high C allocation in new leaves showed a high δ13C variation within the plant (up to 2.5‰). The spatial δ13C variation was significantly correlated with the proportion of second-generation leaves from whole-plant biomass (R2=0.46). According to our results, isotope fractionation in dark respiration can influence the C isotope composition of plant tissues but cannot explain the entire spatial pattern seen. Our study indicates a foliar depletion in 13C during leaf development combined with export of relatively 13C-enriched C by mature source leaves as an important reason for the observed spatial δ13C pattern.
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Affiliation(s)
- Frederik Wegener
- AgroEcosystem Research, BAYCEER, University of Bayreuth, Universitätsstrasse 30, 95447 Bayreuth, Germany
| | - Wolfram Beyschlag
- Experimental and Systems Ecology, University of Bielefeld, Universitätsstrasse 25, 33615 Bielefeld, Germany
| | - Christiane Werner
- AgroEcosystem Research, BAYCEER, University of Bayreuth, Universitätsstrasse 30, 95447 Bayreuth, Germany
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Ghashghaie J, Badeck FW. Opposite carbon isotope discrimination during dark respiration in leaves versus roots - a review. THE NEW PHYTOLOGIST 2014; 201:751-769. [PMID: 24251924 DOI: 10.1111/nph.12563] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 09/15/2013] [Indexed: 05/13/2023]
Abstract
In general, leaves are (13) C-depleted compared with all other organs (e.g. roots, stem/trunk and fruits). Different hypotheses are formulated in the literature to explain this difference. One of these states that CO2 respired by leaves in the dark is (13) C-enriched compared with leaf organic matter, while it is (13) C-depleted in the case of root respiration. The opposite respiratory fractionation between leaves and roots was invoked as an explanation for the widespread between-organ isotopic differences. After summarizing the basics of photosynthetic and post-photosynthetic discrimination, we mainly review the recent findings on the isotopic composition of CO2 respired by leaves (autotrophic organs) and roots (heterotrophic organs) compared with respective plant material (i.e. apparent respiratory fractionation) as well as its metabolic origin. The potential impact of such fractionation on the isotopic signal of organic matter (OM) is discussed. Some perspectives for future studies are also proposed .
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Affiliation(s)
- Jaleh Ghashghaie
- Laboratoire d'Ecologie, Systématique et Evolution (ESE), CNRS UMR8079, Bâtiment 362, Université de Paris-Sud (XI), F-91405, Orsay Cedex, France
| | - Franz W Badeck
- Consiglio per la Ricerca e la sperimentazione in Agricoltura, Genomics research centre (CRA - GPG), Via San Protaso, 302, 29017, Fiorenzuola d'Arda (PC), Italy
- Potsdam Institute for Climate Impact Research (PIK), PF 60 12 03, 14412, Potsdam, Germany
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