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Liu J, An Z, Lin G. Intra-leaf heterogeneities of hydrogen isotope compositions in leaf water and leaf wax of monocots and dicots. Sci Total Environ 2021; 770:145258. [PMID: 33513516 DOI: 10.1016/j.scitotenv.2021.145258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/27/2020] [Accepted: 01/15/2021] [Indexed: 06/12/2023]
Abstract
Several recent studies showed that leaf wax n-alkane δ2H values (δ2Hwax) within a leaf were heterogeneous in a small number of species. It still remains unclear whether the heterogeneity of intra-leaf δ2Hwax values is general for various species, how δ2Hwax values vary spatially and temporally, and whether there is a common explanation for the intra-leaf δ2Hwax heterogeneity in higher plants. Here we compared the hydrogen isotope compositions of leaf wax and corresponding leaf water (δ2Hlw) across leaf sections among a variety of monocot and dicot plant species. There is significant and consistent heterogeneity for both δ2Hwax and δ2Hlw, i.e., base-to-tip 2H-enrichment for monocots (except Hemerocallis citrina, and Dactylis glomerata) whereas base-to-tip and center-to-edge increases in δ2Hwax and δ2Hlw for dicots. The consistent occurrence of variations of δ2Hlw and δ2Hwax values within a leaf imply that δ2Hwax values probably inherit point-to-pint from in-situ δ2Hlw values, and thus the intra-leaf δ2Hwax heterogeneity mainly results from the spatial pattern of intra-leaf δ2Hlw values associated with veinal structures between dicots and monocots. The general heterogeneity of intra-leaf δ2Hwax values further intensifies that it is necessarily needed for in-depth understanding leaf wax biomarker.
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Affiliation(s)
- Jinzhao Liu
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, CAS, Xi'an 710061, China; CAS Center for Excellence in Quaternary Science and Global Change, Xi'an 710061, China.
| | - Zhisheng An
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, CAS, Xi'an 710061, China
| | - Guanghui Lin
- Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing 100084, China
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Kimak A, Kern Z, Leuenberger M. Qualitative Distinction of Autotrophic and Heterotrophic Processes at the Leaf Level by Means of Triple Stable Isotope (C-O-H) Patterns. Front Plant Sci 2015; 6:1008. [PMID: 26635835 PMCID: PMC4656849 DOI: 10.3389/fpls.2015.01008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 10/30/2015] [Indexed: 06/05/2023]
Abstract
Foliar samples were harvested from two oaks, a beech, and a yew at the same site in order to trace the development of the leaves over an entire vegetation season. Cellulose yield and stable isotopic compositions (δ(13)C, δ(18)O, and δD) were analyzed on leaf cellulose. All parameters unequivocally define a juvenile and a mature period in the foliar expansion of each species. The accompanying shifts of the δ(13)C-values are in agreement with the transition from remobilized carbohydrates (juvenile period), to current photosynthates (mature phase). While the opponent seasonal trends of δ(18)O of blade and vein cellulose are in perfect agreement with the state-of-art mechanistic understanding, the lack of this discrepancy for δD, documented for the first time, is unexpected. For example, the offset range of 18 permil (oak veins) to 57 permil (oak blades) in δD may represent a process driven shift from autotrophic to heterotrophic processes. The shared pattern between blade and vein found for both oak and beech suggests an overwhelming metabolic isotope effect on δD that might be accompanied by proton transfer linked to the Calvin-cycle. These results provide strong evidence that hydrogen and oxygen are under different biochemical controls even at the leaf level.
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Affiliation(s)
- Adam Kimak
- Climate and Environmental Physics, Physics Institute, University of BernBern, Switzerland
- Oeschger Centre for Climate Change Research, University of BernBern, Switzerland
| | - Zoltan Kern
- Institute for Geological and Geochemical Research, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences (MTA)Budapest, Hungary
| | - Markus Leuenberger
- Climate and Environmental Physics, Physics Institute, University of BernBern, Switzerland
- Oeschger Centre for Climate Change Research, University of BernBern, Switzerland
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Zhang S, Wen X, Wang J, Yu G, Sun X. The use of stable isotopes to partition evapotranspiration fluxes into evaporation and transpiration. ACTA ACUST UNITED AC 2010; 30:201-9. [DOI: 10.1016/j.chnaes.2010.06.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
Isotopic measurements of leaf water have provided insights into a range of ecophysiological and biogeochemical processes, but require an extraction step which often constitutes the major analytical bottleneck in large-scale studies. Current standard procedures for leaf water analysis are based on cryogenic vacuum or azeotrophic distillation, and are laborious, require sophisticated distillation lines and the use of toxic materials. We report a rapid technique based on centrifugation/filtration of leaf samples pulverised in their original sampling tubes, using a specifically adapted, simple apparatus. The leaf water extracts produced are suitable for isotopic analysis via pyrolysis gas chromatography isotope ratio mass spectrometry (PYR/GC/IRMS). The new method was validated against cryogenic vacuum distillation and showed an overall accuracy of +/-0.5 per thousand (nine grouped comparisons, n = 110) over a range of 21 per thousand. Effects due to the presence of soluble carbohydrates were near the detection limits for most samples analysed, and these effects could be corrected for (the extracted soluble organics could also be used for isotopic analysis). The extraction time for a routine eight-sample subset was reduced from 4 h (cryogenic distillation) to 45 min, limited only by the size of the centrifuge(s) used. This method provides a rapid, low-cost and reliable alternative to conventional vacuum and other distillation methods that can alleviate current restrictions on ecosystem- and global-scale studies that require high-throughput leaf water isotopic analysis.
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Affiliation(s)
- L I Peters
- Department of Environmental Sciences and Energy Research, Weizmann Institute of Science, Rehovot, Israel
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Abstract
The stable hydrogen (delta(2)H) and oxygen (delta(18)O) isotope ratios of organic and inorganic materials record biological and physical processes through the effects of substrate isotopic composition and fractionations that occur as reactions proceed. At large scales, these processes can exhibit spatial predictability because of the effects of coherent climatic patterns over the Earth's surface. Attempts to model spatial variation in the stable isotope ratios of water have been made for decades. Leaf water has a particular importance for some applications, including plant organic materials that record spatial and temporal climate variability and that may be a source of food for migrating animals. It is also an important source of the variability in the isotopic composition of atmospheric gases. Although efforts to model global-scale leaf water isotope ratio spatial variation have been made (especially of delta(18)O), significant uncertainty remains in models and their execution across spatial domains. We introduce here a Geographic Information System (GIS) approach to the generation of global, spatially-explicit isotope landscapes (= isoscapes) of "climate normal" leaf water isotope ratios. We evaluate the approach and the resulting products by comparison with simulation model outputs and point measurements, where obtainable, over the Earth's surface. The isoscapes were generated using biophysical models of isotope fractionation and spatially continuous precipitation isotope and climate layers as input model drivers. Leaf water delta(18)O isoscapes produced here generally agreed with latitudinal averages from GCM/biophysical model products, as well as mean values from point measurements. These results show global-scale spatial coherence in leaf water isotope ratios, similar to that observed for precipitation and validate the GIS approach to modeling leaf water isotopes. These results demonstrate that relatively simple models of leaf water enrichment combined with spatially continuous precipitation isotope ratio and climate data layers yield accurate global leaf water estimates applicable to important questions in ecology and atmospheric science.
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Affiliation(s)
- Jason B West
- Department of Biology, University of Utah, Salt Lake City, Utah, United States of America.
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Ogée J, Cuntz M, Peylin P, Bariac T. Non-steady-state, non-uniform transpiration rate and leaf anatomy effects on the progressive stable isotope enrichment of leaf water along monocot leaves. Plant Cell Environ 2007; 30:367-87. [PMID: 17324225 DOI: 10.1111/j.1365-3040.2006.01621.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
This study focuses on the spatial patterns of transpiration-driven water isotope enrichment (Delta(lw)) along monocot leaves. It has been suggested that these spatial patterns are the result of competing effects of advection and (back-)diffusion of water isotopes along leaf veins and in the mesophyll, but also reflect leaf geometry (e.g. leaf length, interveinal distance) and non-uniform gas-exchange parameters. We therefore developed a two-dimensional model of isotopic leaf water enrichment that incorporates new features, compared with previous models, such as radial diffusion in the xylem, longitudinal diffusion in the mesophyll, non-uniform gas-exchange parameters and non-steady-state effects. The model reproduces well all published measurements of Delta(lw) along monocot leaf blades, except at the leaf tip and given the uncertainties on measurements and model parameters. We show that the longitudinal diffusion in the mesophyll cannot explain the observed reduction in the isotope gradient at the leaf tip. Our results also suggest that the observed differences in Delta(lw) between C(3) and C(4) plants reflect more differences in mesophyll tortuosity rather than in leaf length or interveinal distance. Mesophyll tortuosity is by far the most sensitive parameter and different values are required for different experiments on the same plant species. Finally, using new measurements of non-steady-state, spatially varying leaf water enrichment we show that spatial patterns are in steady state around midday only, just as observed for bulk leaf water enrichment, but can be easily upscaled to the whole leaf level, regardless of their degree of heterogeneity along the leaf.
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Affiliation(s)
- J Ogée
- Ephyse (Functional Ecology and Environmental Physics), INRA, Bordeaux, BP 81 33883 Villenave d'Ornon cedex, France.
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Affek HP, Krisch MJ, Yakir D. Effects of intraleaf variations in carbonic anhydrase activity and gas exchange on leaf C18OO isoflux in Zea mays. New Phytol 2006; 169:321-9. [PMID: 16411935 DOI: 10.1111/j.1469-8137.2005.01603.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Variation in the C18OO content of atmospheric CO2 (delta18Oa) can be used to distinguish photosynthesis from soil respiration, which is based on carbonic anhydrase (CA)-catalyzed 18O exchange between CO2 and 18O-enriched leaf water (delta18Ow). Here we tested the hypothesis that mean leaf delta18Ow and assimilation rates can be used to estimate whole-leaf C18OO flux (isoflux), ignoring intraleaf variations in CA activity and gas exchange parameters. We observed variations in CA activity along the leaf (> 30% decline from the leaf center toward the leaf ends), which were only partially correlated to those in delta18Ow (7 to 21 per thousand), delta18O and delta13C of leaf organic matter (25 to 30 per thousand and -12.8 to -13.2 per thousand, respectively), and substomatal CO2 concentrations (intercellular CO2 concentrations, c(i), at the leaf center were approximately 40% of those at the leaf tip). The combined effect of these variations produced a leaf-integrated isoflux that was different from that predicted based on bulk leaf values. However, because of canceling effects among the influencing parameters, isoflux overestimations were only approximately 10%. Conversely, use of measured parameters from a leaf segment could produce large errors in predicting leaf-integrated C18OO fluxes.
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Affiliation(s)
- Hagit P Affek
- Department of Environmental Sciences and Energy Research, Weizmann Institute, Rehovot 76100, Israel
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Abstract
A model has been derived for the enrichment of heavy isotopes of water in leaves, including progressive enrichment along the leaf. In the model, lighter water is preferentially transpired leaving heavier water to diffuse back into the xylem and be carried further along the leaf. For this pattern to be pronounced, the ratio of advection to diffusion (Péclet number) has to be large in the longitudinal direction, and small in the radial direction. The progressive enrichment along the xylem is less than that occurring at the sites of evaporation in the mesophyll, depending on the isolation afforded by the radial Péclet number. There is an upper bound on enrichment, and effects of ground tissue associated with major veins are included. When transpiration rate is spatially nonuniform, averaging of enrichment occurs more naturally with transpiration weighting than with area-based weighting. This gives zero average enrichment of transpired water, the modified Craig-Gordon equation for average enrichment at the sites of evaporation and the Farquhar and Lloyd (In Stable Isotopes and Plant Carbon-Water Relations, pp. 47-70. Academic Press, New York, USA, 1993) prediction for mesophyll water. Earlier results on the isotopic composition of evolved oxygen and of retro-diffused carbon dioxide are preserved if these processes vary in parallel with transpiration rate. Parallel variation should be indicated approximately by uniform carbon isotope discrimination across the leaf.
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Affiliation(s)
- G. D. Farquhar
- Environmental Biology Group, Research School of Biological Sciences, Institute of Advanced Studies, Australian National University, GPO Box 475, Canberra, ACT 2601, Australia
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PATAKI DIANEE, ELLSWORTH DAVIDS, EVANS RDAVE, GONZALEZ-MELER MIQUEL, KING JOHN, LEAVITT STEVENW, LIN GUANGHUI, MATAMALA ROSER, PENDALL ELISE, SIEGWOLF ROLF, VAN KESSEL CHRIS, EHLERINGER JAMESR. Tracing Changes in Ecosystem Function under Elevated Carbon Dioxide Conditions. Bioscience 2003. [DOI: 10.1641/0006-3568(2003)053[0805:tciefu]2.0.co;2] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Gan KS, Wong SC, Yong JWH, Farquhar GD. (18)O spatial patterns of vein xylem water, leaf water, and dry matter in cotton leaves. Plant Physiol 2002; 130:1008-21. [PMID: 12376664 PMCID: PMC166626 DOI: 10.1104/pp.007419] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2002] [Revised: 05/30/2002] [Accepted: 06/14/2002] [Indexed: 05/20/2023]
Abstract
Three leaf water models (two-pool model, Péclet effect, and string-of-lakes) were assessed for their robustness in predicting leaf water enrichment and its spatial heterogeneity. This was achieved by studying the (18)O spatial patterns of vein xylem water, leaf water, and dry matter in cotton (Gossypium hirsutum) leaves grown at different humidities using new experimental approaches. Vein xylem water was collected from intact transpiring cotton leaves by pressurizing the roots in a pressure chamber, whereas the isotopic content of leaf water was determined without extracting it from fresh leaves with the aid of a purpose-designed leaf punch. Our results indicate that veins have a significant degree of lateral exchange with highly enriched leaf water. Vein xylem water is thus slightly, but progressively enriched in the direction of water flow. Leaf water enrichment is dependent on the relative distances from major veins, with water from the marginal and intercostal regions more enriched and that next to veins and near the leaf base more depleted than the Craig-Gordon modeled enrichment of water at the sites of evaporation. The spatial pattern of leaf water enrichment varies with humidity, as expected from the string-of-lakes model. This pattern is also reflected in leaf dry matter. All three models are realistic, but none could fully account for all of the facets of leaf water enrichment. Our findings acknowledge the presence of capacitance in the ground tissues of vein ribs and highlight the essential need to incorporate Péclet effects into the string-of-lakes model when applying it to leaves.
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Affiliation(s)
- Kim Suan Gan
- Environmental Biology Group, Research School of Biological Sciences, Australian National University, Canberra, Australian Capital Territory 2601, Australia
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Gillon JS, Yakir D. Internal conductance to CO(2) diffusion and C(18)OO discrimination in C(3) leaves. Plant Physiol 2000; 123:201-14. [PMID: 10806237 PMCID: PMC58994 DOI: 10.1104/pp.123.1.201] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/1999] [Accepted: 12/01/1999] [Indexed: 05/20/2023]
Abstract
(18)O discrimination in CO(2) stems from the oxygen exchange between (18)O-enriched water and CO(2) in the chloroplast, a process catalyzed by carbonic anhydrase (CA). A proportion of this (18)O-labeled CO(2) escapes back to the atmosphere, resulting in an effective discrimination against C(18)OO during photosynthesis (Delta(18)O). By constraining the delta(18)O of chloroplast water (delta(e)) by analysis of transpired water and the extent of CO(2)-H(2)O isotopic equilibrium (theta(eq)) by measurements of CA activity (theta(eq) = 0.75-1.0 for tobacco, soybean, and oak), we could apply measured Delta(18)O in a leaf cuvette attached to a mass spectrometer to derive the CO(2) concentration at the physical limit of CA activity, i.e. the chloroplast surface (c(cs)). From the CO(2) drawdown sequence between stomatal cavities from gas exchange (c(i)), from Delta(18)O (c(cs)), and at Rubisco sites from Delta(13)C (c(c)), the internal CO(2) conductance (g(i)) was partitioned into cell wall (g(w)) and chloroplast (g(ch)) components. The results indicated that g(ch) is variable (0.42-1.13 mol m(-2) s(-1)) and proportional to CA activity. We suggest that the influence of CA activity on the CO(2) assimilation rate should be important mainly in plants with low internal conductances.
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Affiliation(s)
- J S Gillon
- Department of Environmental Science and Energy Research, Weizmann Institute of Science, 76100 Rehovot, Israel
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