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Mills C, Bartlett MK, Buckley TN. The poorly-explored stomatal response to temperature at constant evaporative demand. Plant Cell Environ 2024. [PMID: 38602407 DOI: 10.1111/pce.14911] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 02/13/2024] [Accepted: 04/02/2024] [Indexed: 04/12/2024]
Abstract
Changes in leaf temperature are known to drive stomatal responses, because the leaf-to-air water vapour gradient (Δw) increases with temperature if ambient vapour pressure is held constant, and stomata respond to changes in Δw. However, the direct response of stomata to temperature (DRST; the response when Δw is held constant by adjusting ambient humidity) has been examined far less extensively. Though the meagre available data suggest the response is usually positive, results differ widely and defy broad generalisation. As a result, little is known about the DRST. This review discusses the current state of knowledge about the DRST, including numerous hypothesised biophysical mechanisms, potential implications of the response for plant adaptation, and possible impacts of the DRST on plant-atmosphere carbon and water exchange in a changing climate.
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Affiliation(s)
- Colleen Mills
- Department of Plant Sciences, University of California, Davis, USA
| | - Megan K Bartlett
- Department of Viticulture and Enology, University of California, Davis, USA
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, USA
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2
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Triplett G, Buckley TN, Muir CD. Amphistomy increases leaf photosynthesis more in coastal than montane plants of Hawaiian 'ilima (Sida fallax). Am J Bot 2024; 111:e16284. [PMID: 38351495 DOI: 10.1002/ajb2.16284] [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: 09/07/2023] [Revised: 12/19/2023] [Accepted: 12/19/2023] [Indexed: 02/22/2024]
Abstract
PREMISE The adaptive significance of amphistomy (stomata on both upper and lower leaf surfaces) is unresolved. A widespread association between amphistomy and open, sunny habitats suggests the adaptive benefit of amphistomy may be greatest in these contexts, but this hypothesis has not been tested experimentally. Understanding amphistomy informs its potential as a target for crop improvement and paleoenvironment reconstruction. METHODS We developed a method to quantify "amphistomy advantage" (AA $\text{AA}$ ) as the log-ratio of photosynthesis in an amphistomatous leaf to that of the same leaf but with gas exchange blocked through the upper surface (pseudohypostomy). Humidity modulated stomatal conductance and thus enabled comparing photosynthesis at the same total stomatal conductance. We estimatedAA $\text{AA}$ and leaf traits in six coastal (open, sunny) and six montane (closed, shaded) populations of the indigenous Hawaiian species 'ilima (Sida fallax). RESULTS Coastal 'ilima leaves benefit 4.04 times more from amphistomy than montane leaves. Evidence was equivocal with respect to two hypotheses: (1) that coastal leaves benefit more because they are thicker and have lower CO2 conductance through the internal airspace and (2) that they benefit more because they have similar conductance on each surface, as opposed to most conductance being through the lower surface. CONCLUSIONS This is the first direct experimental evidence that amphistomy increases photosynthesis, consistent with the hypothesis that parallel pathways through upper and lower mesophyll increase CO2 supply to chloroplasts. The prevalence of amphistomatous leaves in open, sunny habitats can partially be explained by the increased benefit of amphistomy in "sun" leaves, but the mechanistic basis remains uncertain.
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Affiliation(s)
- Genevieve Triplett
- School of Life Sciences, University of Hawai'i Mānoa, Honolulu, HI, 96822, USA
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, CA, 95616, USA
| | - Christopher D Muir
- School of Life Sciences, University of Hawai'i Mānoa, Honolulu, HI, 96822, USA
- Department of Botany, University of Wisconsin, Madison, WI, 53706, USA
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3
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Coleman D, Windt CW, Buckley TN, Merchant A. Leaf relative water content at 50% stomatal conductance measured by noninvasive NMR is linked to climate of origin in nine species of eucalypt. Plant Cell Environ 2023; 46:3791-3805. [PMID: 37641435 DOI: 10.1111/pce.14700] [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: 04/01/2023] [Revised: 08/07/2023] [Accepted: 08/14/2023] [Indexed: 08/31/2023]
Abstract
Stomata are the gatekeepers of plant water use and must quickly respond to changes in plant water status to ensure plant survival under fluctuating environmental conditions. The mechanism for their closure is highly sensitive to disturbances in leaf water status, which makes isolating their response to declining water content difficult to characterise and to compare responses among species. Using a small-scale non-destructive nuclear magnetic resonance spectrometer as a leaf water content sensor, we measure the stomatal response to rapid induction of water deficit in the leaves of nine species of eucalypt from contrasting climates. We found a strong linear correlation between relative water content at 50% stomatal conductance (RWCgs50 ) and mean annual temperature at the climate of origin of each species. We also show evidence for stomata to maintain control over water loss well below turgor loss point in species adapted to warmer climates and secondary increases in stomatal conductance despite declining water content. We propose that RWCgs50 is a promising trait to guide future investigations comparing stomatal responses to water deficit. It may provide a useful phenotyping trait to delineate tolerance and adaption to hot temperatures and high leaf-to-air vapour pressure deficits.
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Affiliation(s)
- David Coleman
- School of Life, Earth and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney, New South Wales, Australia
| | | | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, California, USA
| | - Andrew Merchant
- School of Life, Earth and Environmental Sciences, Faculty of Science, The University of Sydney, Sydney, New South Wales, Australia
- Institute for Bio-Geosciences, Juelich, Germany
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4
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Scoffoni C, Albuquerque C, Buckley TN, Sack L. The dynamic multi-functionality of leaf water transport outside the xylem. New Phytol 2023; 239:2099-2107. [PMID: 37386735 DOI: 10.1111/nph.19069] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [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: 11/12/2022] [Accepted: 05/12/2023] [Indexed: 07/01/2023]
Abstract
A surge of papers have reported low leaf vulnerability to xylem embolism during drought. Here, we focus on the less studied, and more sensitive, outside-xylem leaf hydraulic responses to multiple internal and external conditions. Studies of 34 species have resolved substantial vulnerability to dehydration of the outside-xylem pathways, and studies of leaf hydraulic responses to light also implicate dynamic outside-xylem responses. Detailed experiments suggest these dynamic responses arise at least in part from strong control of radial water movement across the vein bundle sheath. While leaf xylem vulnerability may influence leaf and plant survival during extreme drought, outside-xylem dynamic responses are important for the control and resilience of water transport and leaf water status for gas exchange and growth.
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Affiliation(s)
- Christine Scoffoni
- Department of Biological Sciences, California State University Los Angeles, 5151 State University Dr., Los Angeles, CA, 90032, USA
| | - Caetano Albuquerque
- Department of Biological Sciences, California State University Los Angeles, 5151 State University Dr., Los Angeles, CA, 90032, USA
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, 1 Shields Ave, Davis, CA, 95616, USA
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, 612 Charles E. Young Dr., Los Angeles, CA, 90095, USA
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5
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Buckley TN. Is carbon, not water, the resource that limits stomatal opening? New Phytol 2023; 238:457-460. [PMID: 36924327 DOI: 10.1111/nph.18818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Affiliation(s)
- Thomas N Buckley
- Department of Plant Sciences, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
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6
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Buckley TN, Frehner EH, Bailey BN. Kinetic factors of physiology and the dynamic light environment influence the economic landscape of short-term hydraulic risk. New Phytol 2023; 238:529-548. [PMID: 36650668 DOI: 10.1111/nph.18739] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [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: 07/29/2022] [Accepted: 01/10/2023] [Indexed: 06/17/2023]
Abstract
Optimality-based models of stomatal conductance unify biophysical and evolutionary constraints and can improve predictions of land-atmosphere carbon and water exchange. Recent models incorporate hydraulic constraints by penalizing excessive stomatal opening in relation to hydraulic damage caused by low water potentials. We used simulation models to test whether penalties based solely on vulnerability curves adequately represent the optimality hypothesis, given that they exclude the effects of kinetic factors on stomatal behavior and integrated carbon balance. To quantify the effects of nonsteady-state phenomena on the landscape of short-term hydraulic risk, we simulated diurnal dynamics of leaf physiology for 10 000 patches of leaf in a canopy and used a ray-tracing model, Helios, to simulate realistic variation in sunfleck dynamics. Our simulations demonstrated that kinetic parameters of leaf physiology and sunfleck properties influence the economic landscape of short-term hydraulic risk, as characterized by the effect of stomatal strategy (gauged by the water potential causing a 50% hydraulic penalty) on both aggregated carbon gain and the aggregated carbon cost of short-term hydraulic risk. Hydraulic penalties in optimization models should be generalized to allow their parameters to account for kinetic factors, in addition to parameters of hydraulic vulnerability.
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Affiliation(s)
- Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, Davis, CA, 95616, USA
| | - Ethan H Frehner
- Department of Plant Sciences, University of California, Davis, Davis, CA, 95616, USA
| | - Brian N Bailey
- Department of Plant Sciences, University of California, Davis, Davis, CA, 95616, USA
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7
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Wong CYS, Jones T, McHugh DP, Gilbert ME, Gepts P, Palkovic A, Buckley TN, Magney TS. TSWIFT: Tower Spectrometer on Wheels for Investigating Frequent Timeseries for high-throughput phenotyping of vegetation physiology. Plant Methods 2023; 19:29. [PMID: 36978119 PMCID: PMC10044391 DOI: 10.1186/s13007-023-01001-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 02/24/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND Remote sensing instruments enable high-throughput phenotyping of plant traits and stress resilience across scale. Spatial (handheld devices, towers, drones, airborne, and satellites) and temporal (continuous or intermittent) tradeoffs can enable or constrain plant science applications. Here, we describe the technical details of TSWIFT (Tower Spectrometer on Wheels for Investigating Frequent Timeseries), a mobile tower-based hyperspectral remote sensing system for continuous monitoring of spectral reflectance across visible-near infrared regions with the capacity to resolve solar-induced fluorescence (SIF). RESULTS We demonstrate potential applications for monitoring short-term (diurnal) and long-term (seasonal) variation of vegetation for high-throughput phenotyping applications. We deployed TSWIFT in a field experiment of 300 common bean genotypes in two treatments: control (irrigated) and drought (terminal drought). We evaluated the normalized difference vegetation index (NDVI), photochemical reflectance index (PRI), and SIF, as well as the coefficient of variation (CV) across the visible-near infrared spectral range (400 to 900 nm). NDVI tracked structural variation early in the growing season, following initial plant growth and development. PRI and SIF were more dynamic, exhibiting variation diurnally and seasonally, enabling quantification of genotypic variation in physiological response to drought conditions. Beyond vegetation indices, CV of hyperspectral reflectance showed the most variability across genotypes, treatment, and time in the visible and red-edge spectral regions. CONCLUSIONS TSWIFT enables continuous and automated monitoring of hyperspectral reflectance for assessing variation in plant structure and function at high spatial and temporal resolutions for high-throughput phenotyping. Mobile, tower-based systems like this can provide short- and long-term datasets to assess genotypic and/or management responses to the environment, and ultimately enable the spectral prediction of resource-use efficiency, stress resilience, productivity and yield.
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Affiliation(s)
| | - Taylor Jones
- Department of Earth & Environment, Boston University, Boston, MA 02215 USA
| | - Devin P. McHugh
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616 USA
| | - Matthew E. Gilbert
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616 USA
| | - Paul Gepts
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616 USA
| | - Antonia Palkovic
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616 USA
| | - Thomas N. Buckley
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616 USA
| | - Troy S. Magney
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616 USA
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8
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Wong CYS, Gilbert ME, Pierce MA, Parker TA, Palkovic A, Gepts P, Magney TS, Buckley TN. Hyperspectral Remote Sensing for Phenotyping the Physiological Drought Response of Common and Tepary Bean. Plant Phenomics 2023; 5:0021. [PMID: 37040284 PMCID: PMC10076057 DOI: 10.34133/plantphenomics.0021] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 12/12/2022] [Indexed: 06/19/2023]
Abstract
Proximal remote sensing offers a powerful tool for high-throughput phenotyping of plants for assessing stress response. Bean plants, an important legume for human consumption, are often grown in regions with limited rainfall and irrigation and are therefore bred to further enhance drought tolerance. We assessed physiological (stomatal conductance and predawn and midday leaf water potential) and ground- and tower-based hyperspectral remote sensing (400 to 2,400 nm and 400 to 900 nm, respectively) measurements to evaluate drought response in 12 common bean and 4 tepary bean genotypes across 3 field campaigns (1 predrought and 2 post-drought). Hyperspectral data in partial least squares regression models predicted these physiological traits (R 2 = 0.20 to 0.55; root mean square percent error 16% to 31%). Furthermore, ground-based partial least squares regression models successfully ranked genotypic drought responses similar to the physiologically based ranks. This study demonstrates applications of high-resolution hyperspectral remote sensing for predicting plant traits and phenotyping drought response across genotypes for vegetation monitoring and breeding population screening.
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9
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Verslues PE, Bailey-Serres J, Brodersen C, Buckley TN, Conti L, Christmann A, Dinneny JR, Grill E, Hayes S, Heckman RW, Hsu PK, Juenger TE, Mas P, Munnik T, Nelissen H, Sack L, Schroeder JI, Testerink C, Tyerman SD, Umezawa T, Wigge PA. Burning questions for a warming and changing world: 15 unknowns in plant abiotic stress. Plant Cell 2023; 35:67-108. [PMID: 36018271 PMCID: PMC9806664 DOI: 10.1093/plcell/koac263] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 08/21/2022] [Indexed: 05/08/2023]
Abstract
We present unresolved questions in plant abiotic stress biology as posed by 15 research groups with expertise spanning eco-physiology to cell and molecular biology. Common themes of these questions include the need to better understand how plants detect water availability, temperature, salinity, and rising carbon dioxide (CO2) levels; how environmental signals interface with endogenous signaling and development (e.g. circadian clock and flowering time); and how this integrated signaling controls downstream responses (e.g. stomatal regulation, proline metabolism, and growth versus defense balance). The plasma membrane comes up frequently as a site of key signaling and transport events (e.g. mechanosensing and lipid-derived signaling, aquaporins). Adaptation to water extremes and rising CO2 affects hydraulic architecture and transpiration, as well as root and shoot growth and morphology, in ways not fully understood. Environmental adaptation involves tradeoffs that limit ecological distribution and crop resilience in the face of changing and increasingly unpredictable environments. Exploration of plant diversity within and among species can help us know which of these tradeoffs represent fundamental limits and which ones can be circumvented by bringing new trait combinations together. Better defining what constitutes beneficial stress resistance in different contexts and making connections between genes and phenotypes, and between laboratory and field observations, are overarching challenges.
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Affiliation(s)
| | - Julia Bailey-Serres
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521, USA
| | - Craig Brodersen
- School of the Environment, Yale University, New Haven, Connecticut 06511, USA
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, California 95616, USA
| | - Lucio Conti
- Department of Biosciences, University of Milan, Milan 20133, Italy
| | - Alexander Christmann
- School of Life Sciences, Technical University Munich, Freising-Weihenstephan 85354, Germany
| | - José R Dinneny
- Department of Biology, Stanford University, Stanford, California 94305, USA
| | - Erwin Grill
- School of Life Sciences, Technical University Munich, Freising-Weihenstephan 85354, Germany
| | - Scott Hayes
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University and Research, Wageningen 6708 PB, The Netherlands
| | - Robert W Heckman
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712, USA
| | - Po-Kai Hsu
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, La Jolla, California 92093, USA
| | - Thomas E Juenger
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712, USA
| | - Paloma Mas
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Barcelona 08193, Spain
- Consejo Superior de Investigaciones Científicas (CSIC), Barcelona 08028, Spain
| | - Teun Munnik
- Department of Plant Cell Biology, Green Life Sciences Cluster, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam NL-1098XH, The Netherlands
| | - Hilde Nelissen
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent 9052, Belgium
- VIB Center for Plant Systems Biology, Ghent 9052, Belgium
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, Institute of the Environment and Sustainability, University of California, Los Angeles, California 90095, USA
| | - Julian I Schroeder
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, La Jolla, California 92093, USA
| | - Christa Testerink
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University and Research, Wageningen 6708 PB, The Netherlands
| | - Stephen D Tyerman
- ARC Center Excellence, Plant Energy Biology, School of Agriculture Food and Wine, University of Adelaide, Adelaide, South Australia 5064, Australia
| | - Taishi Umezawa
- Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 6708 PB, Japan
| | - Philip A Wigge
- Leibniz-Institut für Gemüse- und Zierpflanzenbau, Großbeeren 14979, Germany
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam 14476, Germany
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10
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He N, Yan P, Liu C, Xu L, Li M, Van Meerbeek K, Zhou G, Zhou G, Liu S, Zhou X, Li S, Niu S, Han X, Buckley TN, Sack L, Yu G. Predicting ecosystem productivity based on plant community traits. Trends Plant Sci 2023; 28:43-53. [PMID: 36115777 DOI: 10.1016/j.tplants.2022.08.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [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: 06/25/2021] [Revised: 08/13/2022] [Accepted: 08/19/2022] [Indexed: 06/15/2023]
Abstract
With the rapid accumulation of plant trait data, major opportunities have arisen for the integration of these data into predicting ecosystem primary productivity across a range of spatial extents. Traditionally, traits have been used to explain physiological productivity at cell, organ, or plant scales, but scaling up to the ecosystem scale has remained challenging. Here, we show the need to combine measures of community-level traits and environmental factors to predict ecosystem productivity at landscape or biogeographic scales. We show how theory can extend the production ecology equation to enormous potential for integrating traits into ecological models that estimate productivity-related ecosystem functions across ecological scales and to anticipate the response of terrestrial ecosystems to global change.
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Affiliation(s)
- Nianpeng He
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China; Center for Ecological Research, Northeast Forestry University, Harbin 150040, China.
| | - Pu Yan
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Congcong Liu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Li Xu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Mingxu Li
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Koenraad Van Meerbeek
- Division of Forest, Nature and Landscape, Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium; KU Leuven Plant Institute, KU Leuven, Leuven, Belgium
| | - Guangsheng Zhou
- Chinese Academy of Meteorological Sciences, Haidian District, Beijing, China
| | - Guoyi Zhou
- Institute of Ecology, School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing, China
| | - Shirong Liu
- Key Laboratory of Forest Ecology and Environment, China's State Forestry Administration, Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing, China
| | - Xuhui Zhou
- School of Ecological and Environmental Science, East China Normal University, Shanghai, China
| | - Shenggong Li
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shuli Niu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xingguo Han
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, CA, USA
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, USA.
| | - Guirui Yu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
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11
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Vinod N, Slot M, McGregor IR, Ordway EM, Smith MN, Taylor TC, Sack L, Buckley TN, Anderson-Teixeira KJ. Thermal sensitivity across forest vertical profiles: patterns, mechanisms, and ecological implications. New Phytol 2023; 237:22-47. [PMID: 36239086 DOI: 10.1111/nph.18539] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [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: 10/02/2021] [Accepted: 07/31/2022] [Indexed: 06/16/2023]
Abstract
Rising temperatures are influencing forests on many scales, with potentially strong variation vertically across forest strata. Using published research and new analyses, we evaluate how microclimate and leaf temperatures, traits, and gas exchange vary vertically in forests, shaping tree, and ecosystem ecology. In closed-canopy forests, upper canopy leaves are exposed to the highest solar radiation and evaporative demand, which can elevate leaf temperature (Tleaf ), particularly when transpirational cooling is curtailed by limited stomatal conductance. However, foliar traits also vary across height or light gradients, partially mitigating and protecting against the elevation of upper canopy Tleaf . Leaf metabolism generally increases with height across the vertical gradient, yet differences in thermal sensitivity across the gradient appear modest. Scaling from leaves to trees, canopy trees have higher absolute metabolic capacity and growth, yet are more vulnerable to drought and damaging Tleaf than their smaller counterparts, particularly under climate change. By contrast, understory trees experience fewer extreme high Tleaf 's but have fewer cooling mechanisms and thus may be strongly impacted by warming under some conditions, particularly when exposed to a harsher microenvironment through canopy disturbance. As the climate changes, integrating the patterns and mechanisms reviewed here into models will be critical to forecasting forest-climate feedback.
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Affiliation(s)
- Nidhi Vinod
- Conservation Ecology Center, Smithsonian's National Zoo & Conservation Biology Institute, Front Royal, VA, 22630, USA
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, 90039, USA
| | - Martijn Slot
- Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Panama City, Panama
| | - Ian R McGregor
- Center for Geospatial Analytics, North Carolina State University, Raleigh, NC, 27607, USA
| | - Elsa M Ordway
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, 90039, USA
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Marielle N Smith
- Department of Forestry, Michigan State University, East Lansing, MI, 48824, USA
- School of Natural Sciences, College of Environmental Sciences and Engineering, Bangor University, Bangor, LL57 2DG, UK
| | - Tyeen C Taylor
- Department of Civil & Environmental Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, 90039, USA
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, CA, 95616, USA
| | - Kristina J Anderson-Teixeira
- Conservation Ecology Center, Smithsonian's National Zoo & Conservation Biology Institute, Front Royal, VA, 22630, USA
- Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Panama City, Panama
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12
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Fletcher LR, Scoffoni C, Farrell C, Buckley TN, Pellegrini M, Sack L. Testing the association of relative growth rate and adaptation to climate across natural ecotypes of Arabidopsis. New Phytol 2022; 236:413-432. [PMID: 35811421 DOI: 10.1111/nph.18369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [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: 01/20/2022] [Accepted: 06/28/2022] [Indexed: 06/15/2023]
Abstract
Ecophysiologists have reported a range of relationships, including intrinsic trade-offs across and within species between plant relative growth rate in high resource conditions (RGR) vs adaptation to tolerate cold or arid climates, arising from trait-based mechanisms. Few studies have considered ecotypes within a species, in which the lack of a trade-off would contribute to a wide species range and resilience to climate change. For 15 ecotypes of Arabidopsis thaliana in a common garden we tested for associations between RGR vs adaptation to cold or dry native climates and assessed hypotheses for its mediation by 15 functional traits. Ecotypes native to warmer, drier climates had higher leaf density, leaf mass per area, root mass fraction, nitrogen per leaf area and carbon isotope ratio, and lower osmotic potential at full turgor. Relative growth rate was statistically independent of the climate of the ecotype native range and of individual functional traits. The decoupling of RGR and cold or drought adaptation in Arabidopsis is consistent with multiple stress resistance and avoidance mechanisms for ecotypic climate adaptation and would contribute to the species' wide geographic range and resilience as the climate changes.
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Affiliation(s)
- Leila R Fletcher
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, 90095, USA
- School of the Environment, Yale University, New Haven, CT, 06511, USA
| | - Christine Scoffoni
- Department of Biological Sciences, California State University, Los Angeles, CA, 90032, USA
| | - Colin Farrell
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, 90095, USA
| | - Thomas N Buckley
- Department of Plant Sciences, College of Agricultural and Environmental Sciences, University of California, Davis, CA, 95616, USA
| | - Matteo Pellegrini
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, 90095, USA
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, 90095, USA
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13
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Trueba S, Théroux-Rancourt G, Earles JM, Buckley TN, Love D, Johnson DM, Brodersen C. The three-dimensional construction of leaves is coordinated with water use efficiency in conifers. New Phytol 2022; 233:851-861. [PMID: 34614205 DOI: 10.1111/nph.17772] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 09/21/2021] [Indexed: 06/13/2023]
Abstract
Conifers prevail in the canopies of many terrestrial biomes, holding a great ecological and economic importance globally. Current increases in temperature and aridity are imposing high transpirational demands and resulting in conifer mortality. Therefore, identifying leaf structural determinants of water use efficiency is essential for predicting physiological impacts due to environmental variation. Using synchrotron-generated microtomography imaging, we extracted leaf volumetric anatomy and stomatal traits in 34 species across conifers with a special focus on Pinus, the richest conifer genus. We show that intrinsic water use efficiency (WUEi ) is positively driven by leaf vein volume. Needle-like leaves of Pinus, as opposed to flat leaves or flattened needles of other genera, showed lower mesophyll porosity, decreasing the relative mesophyll volume. This led to increased ratios of stomatal pore number per mesophyll or intercellular airspace volume, which emerged as powerful explanatory variables, predicting both stomatal conductance and WUEi . Our results clarify how the three-dimensional organisation of tissues within the leaf has a direct impact on plant water use and carbon uptake. By identifying a suite of structural traits that influence important physiological functions, our findings can help to understand how conifers may respond to the pressures exerted by climate change.
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Affiliation(s)
- Santiago Trueba
- School of the Environment, Yale University, New Haven, CT, 06511, USA
- University of Bordeaux, INRAE, UMR BIOGECO, Pessac, 33615, France
| | - Guillaume Théroux-Rancourt
- University of Natural Resources and Life Sciences, Vienna, Department of Integrative Biology and Biodiversity Research, Institute of Botany, Vienna, 1180, Austria
| | - J Mason Earles
- Department of Viticulture and Enology, University of California, Davis, CA, 95616, USA
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, CA, 95916, USA
| | - David Love
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA
| | - Daniel M Johnson
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA
| | - Craig Brodersen
- School of the Environment, Yale University, New Haven, CT, 06511, USA
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De La Torre AR, Sekhwal MK, Puiu D, Salzberg SL, Scott AD, Allen B, Neale DB, Chin ARO, Buckley TN. Genome-wide association identifies candidate genes for drought tolerance in coast redwood and giant sequoia. Plant J 2022; 109:7-22. [PMID: 34800071 PMCID: PMC10773529 DOI: 10.1111/tpj.15592] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 11/05/2021] [Accepted: 11/16/2021] [Indexed: 06/13/2023]
Abstract
Drought is a major limitation for survival and growth in plants. With more frequent and severe drought episodes occurring due to climate change, it is imperative to understand the genomic and physiological basis of drought tolerance to be able to predict how species will respond in the future. In this study, univariate and multitrait multivariate genome-wide association study methods were used to identify candidate genes in two iconic and ecosystem-dominating species of the western USA, coast redwood and giant sequoia, using 10 drought-related physiological and anatomical traits and genome-wide sequence-capture single nucleotide polymorphisms. Population-level phenotypic variation was found in carbon isotope discrimination, osmotic pressure at full turgor, xylem hydraulic diameter, and total area of transporting fibers in both species. Our study identified new 78 new marker × trait associations in coast redwood and six in giant sequoia, with genes involved in a range of metabolic, stress, and signaling pathways, among other functions. This study contributes to a better understanding of the genomic basis of drought tolerance in long-generation conifers and helps guide current and future conservation efforts in the species.
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Affiliation(s)
- Amanda R. De La Torre
- School of Forestry, Northern Arizona University, 200 E. Pine Knoll, Flagstaff, AZ 86011, USA
| | - Manoj K. Sekhwal
- School of Forestry, Northern Arizona University, 200 E. Pine Knoll, Flagstaff, AZ 86011, USA
| | - Daniela Puiu
- Department of Biomedical Engineering, Computer Science and Biostatistics & Center for Computational Biology, John Hopkins University, 3100 Wyman Park Dr, Wyman Park Building, Room S220, Baltimore, MD 21211, USA
| | - Steven L. Salzberg
- Department of Biomedical Engineering, Computer Science and Biostatistics & Center for Computational Biology, John Hopkins University, 3100 Wyman Park Dr, Wyman Park Building, Room S220, Baltimore, MD 21211, USA
| | - Alison D. Scott
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Brian Allen
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - David B. Neale
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Alana R. O. Chin
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Thomas N. Buckley
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
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15
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Deng Z, Vice HK, Gilbert ME, Adams MA, Buckley TN. A double-ratio method to measure fast, slow and reverse sap flows. Tree Physiol 2021; 41:2438-2453. [PMID: 34100073 DOI: 10.1093/treephys/tpab081] [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: 10/08/2020] [Accepted: 05/31/2021] [Indexed: 06/12/2023]
Abstract
Sap velocity measurements are useful in fields ranging from plant water relations to hydrology at a variety of scales. Techniques based on pulses of heat are among the most common methods to measure sap velocity, but most lack ability to measure velocities across a wide range, including very high, very low and negative velocities (reverse flow). We propose a new method, the double-ratio method (DRM), which is robust across an unprecedented range of sap velocities and provides real-time estimates of the thermal diffusivity of wood. The DRM employs one temperature sensor upstream (proximal) and two sensors downstream (distal) to the source of heat. This facilitates several theoretical, heat-based approaches to quantifying sap velocity. We tested the DRM using whole-tree lysimetry in Eucalyptus cypellocarpa L.A.S. Johnson and found strong agreement across a wide range of velocities.
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Affiliation(s)
- Zijuan Deng
- Centre for Carbon, Water and Food, The University of Sydney, Brownlow Hill, NSW, 2570
- College of Science and Engineering, Flinders University, Adelaide, Australia
| | - Heather K Vice
- Department of Plant Sciences, University of California, Davis, CA 95616 USA
| | - Matthew E Gilbert
- Department of Plant Sciences, University of California, Davis, CA 95616 USA
| | - Mark A Adams
- School of Science, Faculty of Science, Engineering & Technology, Swinburne University of Technology, Victoria 3122, Australia
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, CA 95616 USA
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16
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Adams MA, Buckley TN, Binkley D, Neumann M, Turnbull TL. CO 2, nitrogen deposition and a discontinuous climate response drive water use efficiency in global forests. Nat Commun 2021; 12:5194. [PMID: 34465788 PMCID: PMC8408268 DOI: 10.1038/s41467-021-25365-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 07/28/2021] [Indexed: 02/07/2023] Open
Abstract
Reduced stomatal conductance is a common plant response to rising atmospheric CO2 and increases water use efficiency (W). At the leaf-scale, W depends on water and nitrogen availability in addition to atmospheric CO2. In hydroclimate models W is a key driver of rainfall, droughts, and streamflow extremes. We used global climate data to derive Aridity Indices (AI) for forests over the period 1965-2015 and synthesised those with data for nitrogen deposition and W derived from stable isotopes in tree rings. AI and atmospheric CO2 account for most of the variance in W of trees across the globe, while cumulative nitrogen deposition has a significant effect only in regions without strong legacies of atmospheric pollution. The relation of aridity and W displays a clear discontinuity. W and AI are strongly related below a threshold value of AI ≈ 1 but are not related where AI > 1. Tree ring data emphasise that effective demarcation of water-limited from non-water-limited behaviour of stomata is critical to improving hydrological models that operate at regional to global scales.
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Affiliation(s)
- Mark A. Adams
- grid.1027.40000 0004 0409 2862Department of Chemistry and Biotechnology, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Melbourne, VIC Australia ,grid.1013.30000 0004 1936 834XSchool of Life and Environmental Sciences, University of Sydney, Sydney, NSW Australia
| | - Thomas N. Buckley
- grid.27860.3b0000 0004 1936 9684Department of Plant Sciences, College of Agricultural and Environmental Sciences, University of California, Davis, CA USA
| | - Dan Binkley
- grid.261120.60000 0004 1936 8040School of Forestry, Northern Arizona University, Flagstaff, AZ USA
| | - Mathias Neumann
- grid.5173.00000 0001 2298 5320Institute of Silviculture, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Tarryn L. Turnbull
- grid.1027.40000 0004 0409 2862Department of Chemistry and Biotechnology, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Melbourne, VIC Australia ,grid.1013.30000 0004 1936 834XSchool of Life and Environmental Sciences, University of Sydney, Sydney, NSW Australia
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17
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Buckley TN. Optimal carbon partitioning helps reconcile the apparent divergence between optimal and observed canopy profiles of photosynthetic capacity. New Phytol 2021; 230:2246-2260. [PMID: 33454975 DOI: 10.1111/nph.17199] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [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: 10/31/2020] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
Photosynthetic capacity per unit irradiance is greater, and the marginal carbon revenue of water (∂A/∂E) is smaller, in shaded leaves than sunlit leaves, apparently contradicting optimization theory. I tested the hypothesis that these patterns arise from optimal carbon partitioning subject to biophysical constraints on leaf water potential. In a whole plant model with two canopy modules, I adjusted carbon partitioning, nitrogen partitioning and leaf water potential to maximize carbon profit or canopy photosynthesis, and recorded how gas exchange parameters compared between shaded and sunlit modules in the optimum. The model predicted that photosynthetic capacity per unit irradiance should be larger, and ∂A/∂E smaller, in shaded modules compared to sunlit modules. This was attributable partly to radiation-driven differences in evaporative demand, and partly to differences in hydraulic conductance arising from the need to balance marginal returns on stem carbon investment between modules. The model verified, however, that invariance in the marginal carbon revenue of N (∂A/∂N) is in fact optimal. The Cowan-Farquhar optimality solution (invariance of ∂A/∂E) does not apply to spatial variation within a canopy. The resulting variation in carbon-water economy explains differences in capacity per unit irradiance, reconciling optimization theory with observations.
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Affiliation(s)
- Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, One Shields Ave, Davis, CA, 95616, USA
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18
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Albuquerque C, Scoffoni C, Brodersen CR, Buckley TN, Sack L, McElrone AJ. Coordinated decline of leaf hydraulic and stomatal conductances under drought is not linked to leaf xylem embolism for different grapevine cultivars. J Exp Bot 2020; 71:7286-7300. [PMID: 33306796 DOI: 10.1093/jxb/eraa392] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [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: 04/21/2020] [Accepted: 10/27/2020] [Indexed: 06/12/2023]
Abstract
Drought decreases water transport capacity of leaves and limits gas exchange, which involves reduced leaf leaf hydraulic conductance (Kleaf) in both the xylem and outside-xylem pathways. Some literature suggests that grapevines are hyper-susceptible to drought-induced xylem embolism. We combined Kleaf and gas exchange measurements, micro-computed tomography of intact leaves, and spatially explicit modeling of the outside-xylem pathways to evaluate the role of vein embolism and Kleaf in the responses of two different grapevine cultivars to drought. Cabernet Sauvignon and Chardonnay exhibited similar vulnerabilities of Kleaf and gs to dehydration, decreasing substantially prior to leaf xylem embolism. Kleaf and gs decreased by 80% for both cultivars by Ψ leaf approximately -0.7 MPa and -1.2 MPa, respectively, while leaf xylem embolism initiated around Ψ leaf = -1.25 MPa in the midribs and little to no embolism was detected in minor veins even under severe dehydration for both cultivars. Modeling results indicated that reduced membrane permeability associated with a Casparian-like band in the leaf vein bundle sheath would explain declines in Kleaf of both cultivars. We conclude that during moderate water stress, changes in the outside-xylem pathways, rather than xylem embolism, are responsible for reduced Kleaf and gs. Understanding this mechanism could help to ensure adequate carbon capture and crop performance under drought.
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Affiliation(s)
- Caetano Albuquerque
- Department of Viticulture and Enology, University of California, Davis, 595 Hilgard Lane, Davis, CA, USA
| | - Christine Scoffoni
- Department of Biological Sciences, California State University, Los Angeles, 5151 State University Drive, Los Angeles, CA, USA
| | - Craig R Brodersen
- School of the Environment, Yale University, 195 Prospect Street, New Haven, CT, USA
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA, USA
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, USA
| | - Andrew J McElrone
- Department of Viticulture and Enology, University of California, Davis, 595 Hilgard Lane, Davis, CA, USA
- USDA-Agricultural Research Service, Davis, CA, USA
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Abstract
Plants often experience multiple stresses in a given day or season, and it is self-evident that given functional traits can provide tolerances of multiple stresses. Yet, the multiple functions of individual traits are rarely explicitly considered in ecology and evolution due to a lack of a quantitative framework. We present a theory for considering the combined importance of the several functions that a single trait can contribute to alleviating multiple stresses. We derive five inter-related general predictions: (1) that trait multifunctionality is overall highly beneficial to fitness; (2) that species possessing multifunctional traits should increase in abundance and in niche breadth; (3) that traits are typically optimized for multiple functions and thus can be far from optimal for individual functions; (4) that the relative importance of each function of a multifunctional trait depends on the environment; and (5) that traits will be often "co-opted" for additional functions during evolution and community assembly. We demonstrate how the theory can be applied quantitatively by examining the multiple functions of leaf trichomes (hairs) using heuristic model simulations, substantiating the general principles. We identify avenues for further development and applications of the theory of trait multifunctionality in ecology and evolution.
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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
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, 1 Shields Avenue, Davis, CA 95616, USA
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20
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Salter WT, Merchant A, Trethowan RM, Richards RA, Buckley TN. Wide variation in the suboptimal distribution of photosynthetic capacity in relation to light across genotypes of wheat. AoB Plants 2020; 12:plaa039. [PMID: 32968474 PMCID: PMC7494244 DOI: 10.1093/aobpla/plaa039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/05/2020] [Indexed: 05/22/2023]
Abstract
Suboptimal distribution of photosynthetic capacity in relation to light among leaves reduces potential whole-canopy photosynthesis. We quantified the degree of suboptimality in 160 genotypes of wheat by directly measuring photosynthetic capacity and daily irradiance in flag and penultimate leaves. Capacity per unit daily irradiance was systematically lower in flag than penultimate leaves in most genotypes, but the ratio (γ) of capacity per unit irradiance between flag and penultimate leaves varied widely across genotypes, from less than 0.5 to over 1.2. Variation in γ was most strongly associated with differences in photosynthetic capacity in penultimate leaves, rather than with flag leaf photosynthesis or canopy light penetration. Preliminary genome-wide association analysis identified nine strong marker-trait associations with this trait, which should be validated in future work in other environments and/or materials. Our modelling suggests canopy photosynthesis could be increased by up to 5 % under sunny conditions by harnessing this variation through selective breeding for increased γ.
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Affiliation(s)
- William T Salter
- School of Life and Environmental Sciences, Sydney Institute of Agriculture, The University of Sydney, Brownlow Hill, NSW, Australia
| | - Andrew Merchant
- School of Life and Environmental Sciences, Sydney Institute of Agriculture, The University of Sydney, Brownlow Hill, NSW, Australia
| | - Richard M Trethowan
- School of Life and Environmental Sciences, Sydney Institute of Agriculture, The University of Sydney, Brownlow Hill, NSW, Australia
| | | | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, Davis, CA, USA
- Corresponding author’s e-mail address:
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21
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Grossiord C, Buckley TN, Cernusak LA, Novick KA, Poulter B, Siegwolf RTW, Sperry JS, McDowell NG. Plant responses to rising vapor pressure deficit. New Phytol 2020; 226:1550-1566. [PMID: 32064613 DOI: 10.1111/nph.16485] [Citation(s) in RCA: 311] [Impact Index Per Article: 77.8] [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: 05/31/2019] [Accepted: 02/04/2020] [Indexed: 05/24/2023]
Abstract
Recent decades have been characterized by increasing temperatures worldwide, resulting in an exponential climb in vapor pressure deficit (VPD). VPD has been identified as an increasingly important driver of plant functioning in terrestrial biomes and has been established as a major contributor in recent drought-induced plant mortality independent of other drivers associated with climate change. Despite this, few studies have isolated the physiological response of plant functioning to high VPD, thus limiting our understanding and ability to predict future impacts on terrestrial ecosystems. An abundance of evidence suggests that stomatal conductance declines under high VPD and transpiration increases in most species up until a given VPD threshold, leading to a cascade of subsequent impacts including reduced photosynthesis and growth, and higher risks of carbon starvation and hydraulic failure. Incorporation of photosynthetic and hydraulic traits in 'next-generation' land-surface models has the greatest potential for improved prediction of VPD responses at the plant- and global-scale, and will yield more mechanistic simulations of plant responses to a changing climate. By providing a fully integrated framework and evaluation of the impacts of high VPD on plant function, improvements in forecasting and long-term projections of climate impacts can be made.
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Affiliation(s)
- Charlotte Grossiord
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903, Birmensdorf, Switzerland
- École Polytechnique Fédérale de Lausanne EPFL, School of Architecture, Civil and Environmental Engineering ENAC, 1015, Lausanne, Switzerland
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, Davis, CA, 95616, USA
| | - Lucas A Cernusak
- College of Science and Engineering, James Cook University, Cairns, Qld, 4814, Australia
| | - Kimberly A Novick
- School of Public and Environmental Affairs, Indiana University Bloomington, Bloomington, IN, 47405, USA
| | - Benjamin Poulter
- Biospheric Sciences Lab, NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA
| | - Rolf T W Siegwolf
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, 8903, Birmensdorf, Switzerland
| | - John S Sperry
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA
| | - Nate G McDowell
- Earth Systems Science Division, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
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Abstract
Stomatal responses to humidity, soil moisture and other factors that influence plant water status are critical drivers of photosynthesis, productivity, water yield, ecohydrology and climate forcing, yet we still lack a thorough mechanistic understanding of these responses. Here I review historical and recent advances in stomatal water relations. Clear evidence now implicates a metabolically mediated response to leaf water status ('hydroactive feedback') in stomatal responses to evaporative demand and soil drought, possibly involving abscisic acid production in leaves. Other hypothetical mechanisms involving vapor and heat transport within leaves may contribute to humidity, light and temperature responses, but require further theoretical clarification and experimental validation. Variation and dynamics in hydraulic conductance, particularly within leaves, may contribute to water status responses. Continuing research to fully resolve mechanisms of stomatal responses to water status should focus on several areas: validating and quantifying the mechanism of leaf-based hydroactive feedback, identifying where in leaves water status is actively sensed, clarifying the role of leaf vapor and energy transport in humidity and temperature responses, and verifying foundational but minimally replicated results of stomatal hydromechanics across species. Clarity on these matters promises to deliver modelers with a tractable and reliable mechanistic model of stomatal responses to water status.
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Affiliation(s)
- Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, One Shields Ave, Davis, CA, 95616, USA
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Adams MA, Buckley TN, Turnbull TL. Rainfall drives variation in rates of change in intrinsic water use efficiency of tropical forests. Nat Commun 2019; 10:3661. [PMID: 31413322 PMCID: PMC6694106 DOI: 10.1038/s41467-019-11679-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 07/30/2019] [Indexed: 11/21/2022] Open
Abstract
Rates of change in intrinsic water use efficiency (W) of trees relative to those in atmospheric [CO2] (ca) have been mostly assessed via short-term studies (e.g., leaf analysis, flux analysis) and/or step increases in ca (e.g., FACE studies). Here we use compiled data for abundances of carbon isotopes in tree stems to show that on decadal scales, rates of change (dW/dca) vary with location and rainfall within the global tropics. For the period 1915-1995, and including corrections for mesophyll conductance and photorespiration, dW/dca for drier tropical forests (receiving ~ 1000 mm rainfall) were at least twice that of the wettest (receiving ~ 4000 mm). The data also empirically confirm theorized roles of tropical forests in changes in atmospheric 13C/12C ratios (the 13C Suess Effect). Further formal analysis of geographic variation in decade-to-century scale dW/dca will be needed to refine current models that predict increases in carbon uptake by forests without hydrological cost.
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Affiliation(s)
- Mark A Adams
- Department of Chemistry and Biotechnology, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Melbourne, VIC, Australia.
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia.
| | - Thomas N Buckley
- Department of Plant Sciences, College of Agricultural and Environmental Sciences, University of California, Davis, CA, USA
| | - Tarryn L Turnbull
- Department of Chemistry and Biotechnology, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Melbourne, VIC, Australia
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
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24
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Salter WT, Merchant AM, Richards RA, Trethowan R, Buckley TN. Rate of photosynthetic induction in fluctuating light varies widely among genotypes of wheat. J Exp Bot 2019; 70:2787-2796. [PMID: 30821324 PMCID: PMC6506768 DOI: 10.1093/jxb/erz100] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [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: 10/04/2018] [Accepted: 02/20/2019] [Indexed: 05/22/2023]
Abstract
Crop photosynthesis and yield are limited by slow photosynthetic induction in sunflecks. We quantified variation in induction kinetics across diverse genotypes of wheat for the first time. Following a preliminary study that hinted at wide variation in induction kinetics across 58 genotypes, we grew 10 genotypes with contrasting responses in a controlled environment and quantified induction kinetics of carboxylation capacity (Vcmax) from dynamic A versus ci curves after a shift from low to high light (from 50 µmol m-2 s-1 to 1500 µmol m-2 s-1), in five flag leaves per genotype. Within-genotype median time for 95% induction (t95) of Vcmax varied 1.8-fold, from 5.2 min to 9.5 min. Our simulations suggest that non-instantaneous induction reduces daily net carbon gain by up to 15%, and that breeding to speed up Vcmax induction in the slowest of our 10 genotypes to match that in the fastest genotype could increase daily net carbon gain by up to 3.4%, particularly for leaves in mid-canopy positions (cumulative leaf area index ≤1.5 m2 m-2), those that experience predominantly short-duration sunflecks, and those with high photosynthetic capacities.
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Affiliation(s)
- William T Salter
- School of Life and Environmental Sciences, Sydney Institute of Agriculture, The University of Sydney, Brownlow Hill, NSW, Australia
| | - Andrew M Merchant
- School of Life and Environmental Sciences, Sydney Institute of Agriculture, The University of Sydney, Brownlow Hill, NSW, Australia
| | | | - Richard Trethowan
- School of Life and Environmental Sciences, Sydney Institute of Agriculture, The University of Sydney, Brownlow Hill, NSW, Australia
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, Davis, CA, USA
- Correspondence:
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Salter WT, Merchant AM, Gilbert ME, Buckley TN. PARbars: Cheap, Easy to Build Ceptometers for Continuous Measurement of Light Interception in Plant Canopies. J Vis Exp 2019. [PMID: 31132041 DOI: 10.3791/59447] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Ceptometry is a technique used to measure the transmittance of photosynthetically active radiation through a plant canopy using multiple light sensors connected in parallel on a long bar. Ceptometry is often used to infer properties of canopy structure and light interception, notably leaf area index (LAI) and effective plant area index (PAIeff). Due to the high cost of commercially available ceptometers, the number of measurements that can be taken is often limited in space and time. This limits the usefulness of ceptometry for studying genetic variability in light interception, and precludes thorough analysis of, and correction for, biases that can skew measurements depending on the time of day. We developed continuously logging ceptometers (called PARbars) that can be produced for USD $75 each and yield high quality data comparable to commercially available alternatives. Here we provide detailed instruction on how to build and calibrate PARbars, how to deploy them in the field and how to estimate PAI from collected transmittance data. We provide representative results from wheat canopies and discuss further considerations that should be made when using PARbars.
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Affiliation(s)
- William T Salter
- School of Life and Environmental Sciences, Sydney Institute of Agriculture, University of Sydney;
| | - Andrew M Merchant
- School of Life and Environmental Sciences, Sydney Institute of Agriculture, University of Sydney
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Buckley TN, Sack L. The humidity inside leaves and why you should care: implications of unsaturation of leaf intercellular airspaces. Am J Bot 2019; 106:618-621. [PMID: 31059119 PMCID: PMC6850086 DOI: 10.1002/ajb2.1282] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 03/22/2019] [Indexed: 05/23/2023]
Affiliation(s)
| | - Lawren Sack
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaLos AngelesCAUSA
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Shrestha A, Buckley TN, Lockhart EL, Barbour MM. The response of mesophyll conductance to short- and long-term environmental conditions in chickpea genotypes. AoB Plants 2019; 11:ply073. [PMID: 30680087 PMCID: PMC6340285 DOI: 10.1093/aobpla/ply073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Accepted: 12/07/2018] [Indexed: 05/23/2023]
Abstract
. Mesophyll conductance (g m) has been shown to vary between genotypes of a number of species and with growth environments, including nitrogen availability, but understanding of g m variability in legumes is limited. We might expect g m in legumes to respond differently to limited nitrogen availability, due to their ability to fix atmospheric N2. Using online stable carbon isotope discrimination method, we quantified genetic variability in g m under ideal conditions, investigated g m response to N source (N2-fixation or inorganic N) and determined the effects of N source and water availability on the rapid response of g m to photosynthetic photon flux density (PPFD) and radiation wavelength in three genotypes of chickpea (Cicer arietinum). Genotypes varied 2-fold in g m under non-limiting environments. N-fed plants had higher g m than N2-fixing plants in one genotype, while g m in the other two genotypes was unaffected. g m response to PPFD was altered by N source in one of three genotypes, in which the g m response to PPFD was statistically significant in N-fed plants but not in N2-fixing plants. There was no clear effect of moderate water stress on the g m response to PPFD and radiation wavelength. Genotypes of a single legume species differ in the sensitivity of g m to both long- and short-term environmental conditions, precluding utility in crop breeding programmes.
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Affiliation(s)
- Arjina Shrestha
- The Centre for Carbon, Water and Food, Faculty of Science, The University of Sydney, Sydney, Australia
| | - Thomas N Buckley
- The Centre for Carbon, Water and Food, Faculty of Science, The University of Sydney, Sydney, Australia
- Department of Plant Sciences, University of California, Davis, CA, USA
| | - Erin L Lockhart
- The Centre for Carbon, Water and Food, Faculty of Science, The University of Sydney, Sydney, Australia
| | - Margaret M Barbour
- The Centre for Carbon, Water and Food, Faculty of Science, The University of Sydney, Sydney, Australia
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Earles JM, Buckley TN, Brodersen CR, Busch FA, Cano FJ, Choat B, Evans JR, Farquhar GD, Harwood R, Huynh M, John GP, Miller ML, Rockwell FE, Sack L, Scoffoni C, Struik PC, Wu A, Yin X, Barbour MM. Embracing 3D Complexity in Leaf Carbon-Water Exchange. Trends Plant Sci 2019; 24:15-24. [PMID: 30309727 DOI: 10.1016/j.tplants.2018.09.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [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: 04/30/2018] [Revised: 09/06/2018] [Accepted: 09/11/2018] [Indexed: 06/08/2023]
Abstract
Leaves are a nexus for the exchange of water, carbon, and energy between terrestrial plants and the atmosphere. Research in recent decades has highlighted the critical importance of the underlying biophysical and anatomical determinants of CO2 and H2O transport, but a quantitative understanding of how detailed 3D leaf anatomy mediates within-leaf transport has been hindered by the lack of a consensus framework for analyzing or simulating transport and its spatial and temporal dynamics realistically, and by the difficulty of measuring within-leaf transport at the appropriate scales. We discuss how recent technological advancements now make a spatially explicit 3D leaf analysis possible, through new imaging and modeling tools that will allow us to address long-standing questions related to plant carbon-water exchange.
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Affiliation(s)
- J Mason Earles
- School of Forestry & Environmental Studies, Yale University, New Haven, CT 06511, USA; Equal contribution
| | - Thomas N Buckley
- Department of Plant Sciences, University of California Davis, CA 95916, USA; Equal contribution
| | - Craig R Brodersen
- School of Forestry & Environmental Studies, Yale University, New Haven, CT 06511, USA
| | - Florian A Busch
- Research School of Biology, Australian National University, Action, ACT 0200, Australia
| | - F Javier Cano
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW 2753, Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW 2753, Australia
| | - John R Evans
- Research School of Biology, Australian National University, Action, ACT 0200, Australia
| | - Graham D Farquhar
- Research School of Biology, Australian National University, Action, ACT 0200, Australia
| | | | - Minh Huynh
- University of Sydney, Sydney, NSW 2006, Australia
| | - Grace P John
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, CA 90095, USA
| | - Megan L Miller
- College of Natural Resources, University of Idaho, Moscow, ID 83844, USA
| | - Fulton E Rockwell
- Department of Organism and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, CA 90095, USA
| | - Christine Scoffoni
- Department of Biological Sciences, California State University Los Angeles, CA 90032, USA
| | - Paul C Struik
- Department of Plant Sciences, Wageningen University, Centre for Crop Systems Analysis, 6700 AK Wageningen, The Netherlands
| | - Alex Wu
- Centre for Plant Science, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Xinyou Yin
- Department of Plant Sciences, Wageningen University, Centre for Crop Systems Analysis, 6700 AK Wageningen, The Netherlands
| | - Margaret M Barbour
- University of Sydney, Sydney, NSW 2006, Australia; www.sydney.edu.au/science/people/margaret.barbour.
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Affiliation(s)
- William T. Salter
- School of Life and Environmental Sciences, Sydney Institute of Agriculture, Univ. of SydneyBrownlow HillNSW2570Australia
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Scoffoni C, Albuquerque C, Cochard H, Buckley TN, Fletcher LR, Caringella MA, Bartlett M, Brodersen CR, Jansen S, McElrone AJ, Sack L. The Causes of Leaf Hydraulic Vulnerability and Its Influence on Gas Exchange in Arabidopsis thaliana. Plant Physiol 2018; 178:1584-1601. [PMID: 30366978 PMCID: PMC6288733 DOI: 10.1104/pp.18.00743] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 10/15/2018] [Indexed: 05/04/2023]
Abstract
The influence of the dynamics of leaf hydraulic conductance (K leaf) diurnally and during dehydration on stomatal conductance and photosynthesis remains unclear. Using the model species Arabidopsis (Arabidopsis thaliana ecotype Columbia-0), we applied a multitiered approach including physiological measurements, high-resolution x-ray microcomputed tomography, and modeling at a range of scales to characterize (1) K leaf decline during dehydration; (2) its basis in the hydraulic conductances of leaf xylem and outside-xylem pathways (K ox); (3) the dependence of its dynamics on irradiance; (4) its impact on diurnal patterns of stomatal conductance and photosynthetic rate; and (5) its influence on gas exchange and survival under simulated drought regimes. Arabidopsis leaves showed strong vulnerability to dehydration diurnally in both gas exchange and hydraulic conductance, despite lack of xylem embolism or conduit collapse above the turgor loss point, indicating a pronounced sensitivity of K ox to dehydration. K leaf increased under higher irradiance in well-hydrated leaves across the full range of water potential, but no shift in K leaf vulnerability was observed. Modeling indicated that responses to dehydration and irradiance are likely attributable to changes in membrane permeability and that a dynamic K ox would contribute strongly to stomatal closure, improving performance, survival, and efficient water use during drought. These findings for Columbia-0 provide a baseline for assessing variation across genotypes in hydraulic traits and their influence on gas exchange during dehydration.
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Affiliation(s)
- Christine Scoffoni
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California 90095
- Department of Biological Sciences, California State University, Los Angeles, California 90032
| | - Caetano Albuquerque
- Department of Viticulture and Enology, University of California, Davis, California 95616
| | - Hervé Cochard
- Université Clermont-Auvergne, Institut National de la Recherche Agronomique, PIAF, F-63000 Clermont-Ferrand, France
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, California 95616
| | - Leila R Fletcher
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California 90095
| | - Marissa A Caringella
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California 90095
| | - Megan Bartlett
- Princeton Environmental Institute, Princeton University, Princeton, New Jersey 08544
| | - Craig R Brodersen
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Ulm, Germany 89081
| | - Andrew J McElrone
- Department of Viticulture and Enology, University of California, Davis, California 95616
- United States Department of Agriculture-Agricultural Research Service, Davis, California 95616
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California 90095
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Salter WT, Gilbert ME, Buckley TN. A multiplexed gas exchange system for increased throughput of photosynthetic capacity measurements. Plant Methods 2018; 14:80. [PMID: 30214467 PMCID: PMC6131801 DOI: 10.1186/s13007-018-0347-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 09/05/2018] [Indexed: 05/22/2023]
Abstract
BACKGROUND Existing methods for directly measuring photosynthetic capacity (Amax) have low throughput, which creates a key bottleneck for pre-breeding and ecological research. Currently available commercial leaf gas exchange systems are not designed to maximize throughput, on either a cost or time basis. RESULTS We present a novel multiplexed semi-portable gas exchange system, OCTOflux, that can measure Amax with approximately 4-7 times the throughput of commercial devices, despite a lower capital cost. The main time efficiency arises from having eight leaves simultaneously acclimate to saturating CO2 and high light levels; the long acclimation periods for each leaf (13.8 min on average in this study) thus overlap to a large degree, rather than occurring sequentially. The cost efficiency arises partly from custom-building the system and thus avoiding commercial costs like distribution, marketing and profit, and partly from optimizing the system's design for Amax throughput rather than flexibility for other types of measurements. CONCLUSION Throughput for Amax measurements can be increased greatly, on both a cost and time basis, by multiplexing gas streams from several leaf chambers connected to a single gas analyzer. This can help overcome the bottleneck in breeding and ecological research posed by limited phenotyping throughput for Amax.
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Affiliation(s)
- William T. Salter
- School of Life and Environmental Sciences, Sydney Institute of Agriculture, The University of Sydney, Sydney, NSW Australia
| | - Matthew E. Gilbert
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616 USA
| | - Thomas N. Buckley
- Department of Plant Sciences, University of California, Davis, Davis, CA 95616 USA
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Adams MA, Buchmann N, Sprent J, Buckley TN, Turnbull TL. Crops, Nitrogen, Water: Are Legumes Friend, Foe, or Misunderstood Ally? Trends Plant Sci 2018; 23:539-550. [PMID: 29559299 DOI: 10.1016/j.tplants.2018.02.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [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: 11/22/2017] [Revised: 02/19/2018] [Accepted: 02/23/2018] [Indexed: 06/08/2023]
Abstract
Biological nitrogen fixation (BNF) by crop legumes reduces demand for industrial nitrogen fixation (INF). Nonetheless, rates of BNF in agriculture remain low, with strong negative feedback to BNF from reactive soil nitrogen (N) and drought. We show that breeding for yield has resulted in strong relationships between photosynthesis and leaf N in non-leguminous crops, whereas grain legumes show strong relations between leaf N and water use efficiency (WUE). We contrast these understandings with other studies that draw attention to the water costs of grain legume crops, and their potential for polluting the biosphere with N. We propose that breeding grain legumes for reduced stomatal conductance can increase WUE without compromising production or BNF. Legume crops remain a better bet than relying on INF.
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Affiliation(s)
- Mark A Adams
- Swinburne University, PO Box 218, Hawthorn, VIC 3122, Australia; Centre for Carbon Water and Food, The University of Sydney, 380 Werombi Road, Camden, NSW 2480, Australia.
| | - Nina Buchmann
- ETH Zurich, Universitätstrasse 2, 8092 Zürich, Switzerland
| | - Janet Sprent
- Division of Plant Sciences, University of Dundee at JHI, Invergowrie, Dundee, DD2 5DA, UK
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Tarryn L Turnbull
- Centre for Carbon Water and Food, The University of Sydney, 380 Werombi Road, Camden, NSW 2480, Australia
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Adams MA, Buckley TN, Salter WT, Buchmann N, Blessing CH, Turnbull TL. Contrasting responses of crop legumes and cereals to nitrogen availability. New Phytol 2018; 217:1475-1483. [PMID: 29178286 DOI: 10.1111/nph.14918] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [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: 08/12/2017] [Accepted: 10/21/2017] [Indexed: 06/07/2023]
Abstract
In nonagricultural systems, the relationship between intrinsic water-use efficiency (WUEi ) and leaf nitrogen (Narea ) is known to be stronger for legumes than for nonlegumes. We tested whether these relationships are retained for major agricultural legumes and nonlegumes. We compared the response to N nutrition of WUEi (and its component parts, photosynthesis (Asat ) and stomatal conductance (gs )) for legumes Cicer arietinum, Glycine max, Lupinus alba and Vicia faba, nonlegume dicots Brassica napus and Helianthus annus, and nonlegume cereals Hordeum vulgare and Triticum aestivum. Surprisingly, and in contrast to studied cereals and nonlegume dicots, Narea was positively related to photosynthesis in the legumes, explaining nearly half of the variance in Asat . WUEi was tightly coupled to Narea for agricultural legumes and nonlegume dicots, but not for cereal crops. Our analysis suggests that breeding efforts to reduce gs in legumes could increase WUEi by 120-218% while maintaining Asat at nonlegume values. Physiologically informed breeding of legumes can enhance sustainable agriculture by reducing requirements for water and N.
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Affiliation(s)
- Mark A Adams
- Department of Chemistry and Biotechnology, Faculty of Science, Engineering and Technology, Swinburne University, PO Box 218, Hawthorn, Vic, 3122, Australia
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, One Shields Ave, Davis, CA, 95616, USA
| | - William T Salter
- School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, 380 Werombi Rd, Camden, NSW, 2570, Australia
| | - Nina Buchmann
- ETH Zurich, Universitätstrasse 2, 8092, Zürich, Switzerland
| | - Carola H Blessing
- School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, 380 Werombi Rd, Camden, NSW, 2570, Australia
| | - Tarryn L Turnbull
- School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, 380 Werombi Rd, Camden, NSW, 2570, Australia
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34
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Sack L, John GP, Buckley TN. ABA Accumulation in Dehydrating Leaves Is Associated with Decline in Cell Volume, Not Turgor Pressure. Plant Physiol 2018; 176:489-495. [PMID: 29061906 PMCID: PMC5761807 DOI: 10.1104/pp.17.01097] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 10/23/2017] [Indexed: 05/18/2023]
Abstract
Reanalysis of published experimental data shows that in dehydrating leaves ABA accumulation is linked with reduction of cell volume rather than turgor, providing clues toward signaling mechanisms.
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Affiliation(s)
- Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, California, 90095
| | - Grace P John
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, California, 90095
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, Davis, California 95616
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35
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Buckley TN, Vice H, Adams MA. The Kok effect in Vicia faba cannot be explained solely by changes in chloroplastic CO 2 concentration. New Phytol 2017; 216:1064-1071. [PMID: 28857173 DOI: 10.1111/nph.14775] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [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: 06/18/2017] [Accepted: 08/05/2017] [Indexed: 06/07/2023]
Abstract
The Kok effect - an abrupt decline in quantum yield (QY) of net CO2 assimilation at low photosynthetic photon flux density (PPFD) - is widely used to estimate respiration in the light (R), which assumes the effect is caused by light suppression of R. A recent report suggested much of the Kok effect can be explained by declining chloroplastic CO2 concentration (cc ) at low PPFD. Several predictions arise from the hypothesis that the Kok effect is caused by declining cc , and we tested these predictions in Vicia faba. We measured CO2 exchange at low PPFD, in 2% and 21% oxygen, in developing and mature leaves, which differed greatly in R in darkness. Our results contradicted each of the predictions based on the cc effect: QY exceeded the theoretical maximum value for photosynthetic CO2 uptake; QY was larger in 21% than 2% oxygen; and the change in QY at the Kok effect breakpoint was unaffected by oxygen. Our results strongly suggest the Kok effect arises largely from a progressive decline in R with PPFD that includes both oxygen-sensitive and -insensitive components. We suggest an improved Kok method that accounts for high cc at low PPFD.
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Affiliation(s)
- Thomas N Buckley
- Sydney Institute of Agriculture, University of Sydney, Narrabri, NSW, 2390, Australia
| | - Heather Vice
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Mark A Adams
- Faculty of Science, Engineering and Technology, Swinburne University of Technology, PO Box 218, Hawthorn, Vic, 3122, Australia
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Tcherkez G, Gauthier P, Buckley TN, Busch FA, Barbour MM, Bruhn D, Heskel MA, Gong XY, Crous KY, Griffin K, Way D, Turnbull M, Adams MA, Atkin OK, Farquhar GD, Cornic G. Leaf day respiration: low CO 2 flux but high significance for metabolism and carbon balance. New Phytol 2017; 216:986-1001. [PMID: 28967668 DOI: 10.1111/nph.14816] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [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: 06/20/2017] [Accepted: 08/13/2017] [Indexed: 05/04/2023]
Abstract
Contents 986 I. 987 II. 987 III. 988 IV. 991 V. 992 VI. 995 VII. 997 VIII. 998 References 998 SUMMARY: It has been 75 yr since leaf respiratory metabolism in the light (day respiration) was identified as a low-flux metabolic pathway that accompanies photosynthesis. In principle, it provides carbon backbones for nitrogen assimilation and evolves CO2 and thus impacts on plant carbon and nitrogen balances. However, for a long time, uncertainties have remained as to whether techniques used to measure day respiratory efflux were valid and whether day respiration responded to environmental gaseous conditions. In the past few years, significant advances have been made using carbon isotopes, 'omics' analyses and surveys of respiration rates in mesocosms or ecosystems. There is substantial evidence that day respiration should be viewed as a highly dynamic metabolic pathway that interacts with photosynthesis and photorespiration and responds to atmospheric CO2 mole fraction. The view of leaf day respiration as a constant and/or negligible parameter of net carbon exchange is now outdated and it should now be regarded as a central actor of plant carbon-use efficiency.
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Affiliation(s)
- Guillaume Tcherkez
- Research School of Biology, College of Science, and ARC Center of Excellence for Translational Photosynthesis, Australian National University, Canberra, ACT, 2601, Australia
| | - Paul Gauthier
- Department of Geosciences, Princeton University, Princeton, NJ, 08540, USA
| | - Thomas N Buckley
- IA Watson Grains Research Centre, University of Sydney, 12656 Newell Hwy, Narrabri, NSW, 2390, Australia
| | - Florian A Busch
- Research School of Biology, College of Science, and ARC Center of Excellence for Translational Photosynthesis, Australian National University, Canberra, ACT, 2601, Australia
| | - Margaret M Barbour
- Centre for Carbon, Water and Food, University of Sydney, 380 Werombi Rd, Brownlow Hill, NSW, 2570, Australia
| | - Dan Bruhn
- Section of Biology and Environmental Science, Department of Chemistry and Bioscience, Aalborg University, 9220, Aalborg East, Denmark
| | - Mary A Heskel
- The Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA, 02543, USA
| | - Xiao Ying Gong
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising, Germany
| | - Kristine Y Crous
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Kevin Griffin
- Department of Ecology, Evolution and Environmental Biology (E3B), Columbia University, 1200 Amsterdam Avenue, New York, NY, 10027, USA
| | - Danielle Way
- Department of Biology, University of Western Ontario, London, ON, N6A 5B7, Canada
| | - Matthew Turnbull
- Centre for Integrative Ecology, School of Biological Sciences, University of Canterbury, PB 4800, Christchurch, New Zealand
| | - Mark A Adams
- Centre for Carbon, Water and Food, University of Sydney, 380 Werombi Rd, Brownlow Hill, NSW, 2570, Australia
| | - Owen K Atkin
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Science, Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - Graham D Farquhar
- Research School of Biology, College of Science, and ARC Center of Excellence for Translational Photosynthesis, Australian National University, Canberra, ACT, 2601, Australia
| | - Gabriel Cornic
- Ecologie Systématique Evolution, Université Paris-Sud, 91405, Orsay Cedex, France
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Bellasio C, Quirk J, Buckley TN, Beerling DJ. A Dynamic Hydro-Mechanical and Biochemical Model of Stomatal Conductance for C 4 Photosynthesis. Plant Physiol 2017; 175:104-119. [PMID: 28751312 PMCID: PMC5580762 DOI: 10.1104/pp.17.00666] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 07/24/2017] [Indexed: 05/10/2023]
Abstract
C4 plants are major grain (maize [Zea mays] and sorghum [Sorghum bicolor]), sugar (sugarcane [Saccharum officinarum]), and biofuel (Miscanthus spp.) producers and contribute ∼20% to global productivity. Plants lose water through stomatal pores in order to acquire CO2 (assimilation [A]) and control their carbon-for-water balance by regulating stomatal conductance (gS). The ability to mechanistically predict gS and A in response to atmospheric CO2, water availability, and time is critical for simulating stomatal control of plant-atmospheric carbon and water exchange under current, past, or future environmental conditions. Yet, dynamic mechanistic models for gS are lacking, especially for C4 photosynthesis. We developed and coupled a hydromechanical model of stomatal behavior with a biochemical model of C4 photosynthesis, calibrated using gas-exchange measurements in maize, and extended the coupled model with time-explicit functions to predict dynamic responses. We demonstrated the wider applicability of the model with three additional C4 grass species in which interspecific differences in stomatal behavior could be accounted for by fitting a single parameter. The model accurately predicted steady-state responses of gS to light, atmospheric CO2 and oxygen, soil drying, and evaporative demand as well as dynamic responses to light intensity. Further analyses suggest that the effect of variable leaf hydraulic conductance is negligible. Based on the model, we derived a set of equations suitable for incorporation in land surface models. Our model illuminates the processes underpinning stomatal control in C4 plants and suggests that the hydraulic benefits associated with fast stomatal responses of C4 grasses may have supported the evolution of C4 photosynthesis.
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Affiliation(s)
- Chandra Bellasio
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, United Kingdom
- Trees and Timber Institute, National Research Council of Italy, 50019 Florence, Italy
| | - Joe Quirk
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Thomas N Buckley
- Sydney Institute of Agriculture, University of Sydney, Narrabri, New South Wales 2390, Australia
| | - David J Beerling
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, United Kingdom
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Abstract
Recent advances have improved our ability to model stomatal conductance using process- or optimality-based models, and continuing research should focus on how stomata sense leaf turgor and on how to quantify the direct carbon costs of low leaf water potential.
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Affiliation(s)
- Thomas N Buckley
- Plant Breeding Institute, Sydney Institute of Agriculture, The University of Sydney, Narrabri NSW 2390, Australia
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39
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Barbour MM, Farquhar GD, Buckley TN. Leaf water stable isotopes and water transport outside the xylem. Plant Cell Environ 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] [What about the content of this article? (0)] [Affiliation(s)] [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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Buckley TN, Sack L, Farquhar GD. Optimal plant water economy. Plant Cell Environ 2017; 40:881-896. [PMID: 27644069 DOI: 10.1111/pce.12823] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [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: 05/27/2016] [Revised: 08/22/2016] [Accepted: 08/24/2016] [Indexed: 05/13/2023]
Abstract
It was shown over 40 years ago that plants maximize carbon gain for a given rate of water loss if stomatal conductance, gs , varies in response to external and internal conditions such that the marginal carbon revenue of water, ∂A/∂E, remains constant over time. This theory has long held promise for understanding the physiological ecology of water use and for informing models of plant-atmosphere interactions. Full realization of this potential hinges on three questions: (i) Are analytical approximations adequate for applying the theory at diurnal time scales? (ii) At what time scale is it realistic and appropriate to apply the theory? (iii) How should gs vary to maximize growth over long time scales? We review the current state of understanding for each of these questions and describe future research frontiers. In particular, we show that analytical solutions represent the theory quite poorly, especially when boundary layer or mesophyll resistances are significant; that diurnal variations in hydraulic conductance may help or hinder maintenance of ∂A/∂E, and the matter requires further study; and that optimal diurnal responses are distinct from optimal long-term variations in gs , which emerge from optimal shifts in carbon partitioning at the whole-plant scale.
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Affiliation(s)
- Thomas N Buckley
- Plant Breeding Institute, Faculty of Agriculture and Environment, The University of Sydney, Narrabri, New South Wales, 2390, Australia
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, 90095, United States
| | - Graham D Farquhar
- Research School of Biology, Australian National University, Canberra, 0200, Australia
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Tcherkez G, Gauthier P, Buckley TN, Busch FA, Barbour MM, Bruhn D, Heskel MA, Gong XY, Crous K, Griffin KL, Way DA, Turnbull MH, Adams MA, Atkin OK, Bender M, Farquhar GD, Cornic G. Tracking the origins of the Kok effect, 70 years after its discovery. New Phytol 2017; 214:506-510. [PMID: 28318034 DOI: 10.1111/nph.14527] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Affiliation(s)
- Guillaume Tcherkez
- Research School of Biology, College of Medicine, Biology and Environment, Australian National University, Canberra, ACT, 2601, Australia
| | - Paul Gauthier
- Department of Geosciences, Princeton University, Princeton, NJ, 08540, USA
| | - Thomas N Buckley
- IA Watson Grains Research Centre, University of Sydney, 12656 Newell Hwy, Narrabri, NSW, 2390, Australia
| | - Florian A Busch
- Research School of Biology, College of Medicine, Biology and Environment, Australian National University, Canberra, ACT, 2601, Australia
| | - Margaret M Barbour
- Centre for Carbon, Water and Food, University of Sydney, 380 Werombi Rd, Brownlow Hill, NSW, 2570, Australia
| | - Dan Bruhn
- Section of Biology and Environmental Science, Department of Chemistry and Bioscience, Aalborg University, 9220, Aalborg East, Denmark
| | - Mary A Heskel
- The Ecosystems Centre, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA, 02543, USA
| | - Xiao Ying Gong
- Lehrstuhl für Grünlandlehre, Technische Universität München, Alte Akademie 12, 85354, Freising, Germany
| | - Kristine Crous
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Kevin L Griffin
- Department of Ecology, Evolution and Environmental Biology (E3B), Columbia University, 1200 Amsterdam Avenue, Palisades, NY, 10027, USA
| | - Danielle A Way
- Department of Biology, University of Western Ontario, London, ON N6A 5B7, Canada
| | - Matthew H Turnbull
- Centre for Integrative Ecology, School of Biological Sciences, University of Canterbury, PB 4800, Christchurch, New Zealand
| | - Mark A Adams
- Centre for Carbon, Water and Food, University of Sydney, 380 Werombi Rd, Brownlow Hill, NSW, 2570, Australia
| | - Owen K Atkin
- Division of Plant Science, ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, College of Medicine, Biology and Environment, Australian National University, Canberra, ACT, 2601, Australia
| | - Michael Bender
- Department of Geosciences, Princeton University, Princeton, NJ, 08540, USA
| | - Graham D Farquhar
- Research School of Biology, College of Medicine, Biology and Environment, Australian National University, Canberra, ACT, 2601, Australia
| | - Gabriel Cornic
- Ecologie Systématique Evolution, Université Paris-Sud, 91405, Orsay Cedex, France
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Buckley TN, John GP, Scoffoni C, Sack L. The Sites of Evaporation within Leaves. Plant Physiol 2017; 173:1763-1782. [PMID: 28153921 PMCID: PMC5338672 DOI: 10.1104/pp.16.01605] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Accepted: 02/01/2017] [Indexed: 05/18/2023]
Abstract
The sites of evaporation within leaves are unknown, but they have drawn attention for decades due to their perceived implications for many factors, including patterns of leaf isotopic enrichment, the maintenance of mesophyll water status, stomatal regulation, and the interpretation of measured stomatal and leaf hydraulic conductances. We used a spatially explicit model of coupled water and heat transport outside the xylem, MOFLO 2.0, to map the distribution of net evaporation across leaf tissues in relation to anatomy and environmental parameters. Our results corroborate earlier predictions that most evaporation occurs from the epidermis at low light and moderate humidity but that the mesophyll contributes substantially when the leaf center is warmed by light absorption, and more so under high humidity. We also found that the bundle sheath provides a significant minority of evaporation (15% in darkness and 18% in high light), that the vertical center of amphistomatous leaves supports net condensation, and that vertical temperature gradients caused by light absorption vary over 10-fold across species, reaching 0.3°C. We show that several hypotheses that depend on the evaporating sites require revision in light of our findings, including that experimental measurements of stomatal and hydraulic conductances should be affected directly by changes in the location of the evaporating sites. We propose a new conceptual model that accounts for mixed-phase water transport outside the xylem. These conclusions have far-reaching implications for inferences in leaf hydraulics, gas exchange, water use, and isotope physiology.
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Affiliation(s)
- Thomas N Buckley
- Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, Narrabri 2390, Australia (T.N.B.); and
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California 90095 (G.P.J., C.S., L.S.)
| | - Grace P John
- Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, Narrabri 2390, Australia (T.N.B.); and
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California 90095 (G.P.J., C.S., L.S.)
| | - Christine Scoffoni
- Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, Narrabri 2390, Australia (T.N.B.); and
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California 90095 (G.P.J., C.S., L.S.)
| | - Lawren Sack
- Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, Narrabri 2390, Australia (T.N.B.); and
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California 90095 (G.P.J., C.S., L.S.)
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John GP, Scoffoni C, Buckley TN, Villar R, Poorter H, Sack L. The anatomical and compositional basis of leaf mass per area. Ecol Lett 2017; 20:412-425. [DOI: 10.1111/ele.12739] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 09/12/2016] [Accepted: 12/21/2016] [Indexed: 12/25/2022]
Affiliation(s)
- Grace P. John
- Department of Ecology and Evolutionary Biology University of California Los Angeles 621 Charles E. Young Drive South Los Angeles CA90095 USA
| | - Christine Scoffoni
- Department of Ecology and Evolutionary Biology University of California Los Angeles 621 Charles E. Young Drive South Los Angeles CA90095 USA
| | - Thomas N. Buckley
- Plant Breeding Institute Sydney Institute of Agriculture The University of Sydney 12656, Newell Hwy Narrabri NSW2390 Australia
| | - Rafael Villar
- Área de Ecología Universidad de Córdoba Edificio Celestino Mutis Campus de Rabanales 14071 Córdoba Spain
| | - Hendrik Poorter
- Plant Sciences (IBG2), Forschungszentrum Jülich GmbH D‐52425 Jülich Germany
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology University of California Los Angeles 621 Charles E. Young Drive South Los Angeles CA90095 USA
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Scoffoni C, Albuquerque C, Brodersen CR, Townes SV, John GP, Bartlett MK, Buckley TN, McElrone AJ, Sack L. Outside-Xylem Vulnerability, Not Xylem Embolism, Controls Leaf Hydraulic Decline during Dehydration. Plant Physiol 2017; 173:1197-1210. [PMID: 28049739 PMCID: PMC5291720 DOI: 10.1104/pp.16.01643] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 12/28/2016] [Indexed: 05/18/2023]
Abstract
Leaf hydraulic supply is crucial to maintaining open stomata for CO2 capture and plant growth. During drought-induced dehydration, the leaf hydraulic conductance (Kleaf) declines, which contributes to stomatal closure and, eventually, to leaf death. Previous studies have tended to attribute the decline of Kleaf to embolism in the leaf vein xylem. We visualized at high resolution and quantified experimentally the hydraulic vulnerability of xylem and outside-xylem pathways and modeled their respective influences on plant water transport. Evidence from all approaches indicated that the decline of Kleaf during dehydration arose first and foremost due to the vulnerability of outside-xylem tissues. In vivo x-ray microcomputed tomography of dehydrating leaves of four diverse angiosperm species showed that, at the turgor loss point, only small fractions of leaf vein xylem conduits were embolized, and substantial xylem embolism arose only under severe dehydration. Experiments on an expanded set of eight angiosperm species showed that outside-xylem hydraulic vulnerability explained 75% to 100% of Kleaf decline across the range of dehydration from mild water stress to beyond turgor loss point. Spatially explicit modeling of leaf water transport pointed to a role for reduced membrane conductivity consistent with published data for cells and tissues. Plant-scale modeling suggested that outside-xylem hydraulic vulnerability can protect the xylem from tensions that would induce embolism and disruption of water transport under mild to moderate soil and atmospheric droughts. These findings pinpoint outside-xylem tissues as a central locus for the control of leaf and plant water transport during progressive drought.
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Affiliation(s)
- Christine Scoffoni
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, 90095 (C.S., S.V.T., G.P.J., M.K.B., L.S.);
- Department of Biology, Utah State University, Logan, Utah 84322 (C.S.);
- Department of Viticulture and Enology, University of California, Davis, California 95616 (C.A., A.J.M.);
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511 (C.R.B.);
- IA Watson Grains Research Centre, Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, Narrabri, New South Wales 2390, Australia (T.N.B.); and
- United States Department of Agriculture-Agricultural Research Service, Davis, California 95616 (A.J.M.)
| | - Caetano Albuquerque
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, 90095 (C.S., S.V.T., G.P.J., M.K.B., L.S.)
- Department of Biology, Utah State University, Logan, Utah 84322 (C.S.)
- Department of Viticulture and Enology, University of California, Davis, California 95616 (C.A., A.J.M.)
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511 (C.R.B.)
- IA Watson Grains Research Centre, Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, Narrabri, New South Wales 2390, Australia (T.N.B.); and
- United States Department of Agriculture-Agricultural Research Service, Davis, California 95616 (A.J.M.)
| | - Craig R Brodersen
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, 90095 (C.S., S.V.T., G.P.J., M.K.B., L.S.)
- Department of Biology, Utah State University, Logan, Utah 84322 (C.S.)
- Department of Viticulture and Enology, University of California, Davis, California 95616 (C.A., A.J.M.)
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511 (C.R.B.)
- IA Watson Grains Research Centre, Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, Narrabri, New South Wales 2390, Australia (T.N.B.); and
- United States Department of Agriculture-Agricultural Research Service, Davis, California 95616 (A.J.M.)
| | - Shatara V Townes
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, 90095 (C.S., S.V.T., G.P.J., M.K.B., L.S.)
- Department of Biology, Utah State University, Logan, Utah 84322 (C.S.)
- Department of Viticulture and Enology, University of California, Davis, California 95616 (C.A., A.J.M.)
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511 (C.R.B.)
- IA Watson Grains Research Centre, Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, Narrabri, New South Wales 2390, Australia (T.N.B.); and
- United States Department of Agriculture-Agricultural Research Service, Davis, California 95616 (A.J.M.)
| | - Grace P John
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, 90095 (C.S., S.V.T., G.P.J., M.K.B., L.S.)
- Department of Biology, Utah State University, Logan, Utah 84322 (C.S.)
- Department of Viticulture and Enology, University of California, Davis, California 95616 (C.A., A.J.M.)
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511 (C.R.B.)
- IA Watson Grains Research Centre, Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, Narrabri, New South Wales 2390, Australia (T.N.B.); and
- United States Department of Agriculture-Agricultural Research Service, Davis, California 95616 (A.J.M.)
| | - Megan K Bartlett
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, 90095 (C.S., S.V.T., G.P.J., M.K.B., L.S.)
- Department of Biology, Utah State University, Logan, Utah 84322 (C.S.)
- Department of Viticulture and Enology, University of California, Davis, California 95616 (C.A., A.J.M.)
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511 (C.R.B.)
- IA Watson Grains Research Centre, Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, Narrabri, New South Wales 2390, Australia (T.N.B.); and
- United States Department of Agriculture-Agricultural Research Service, Davis, California 95616 (A.J.M.)
| | - Thomas N Buckley
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, 90095 (C.S., S.V.T., G.P.J., M.K.B., L.S.)
- Department of Biology, Utah State University, Logan, Utah 84322 (C.S.)
- Department of Viticulture and Enology, University of California, Davis, California 95616 (C.A., A.J.M.)
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511 (C.R.B.)
- IA Watson Grains Research Centre, Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, Narrabri, New South Wales 2390, Australia (T.N.B.); and
- United States Department of Agriculture-Agricultural Research Service, Davis, California 95616 (A.J.M.)
| | - Andrew J McElrone
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, 90095 (C.S., S.V.T., G.P.J., M.K.B., L.S.)
- Department of Biology, Utah State University, Logan, Utah 84322 (C.S.)
- Department of Viticulture and Enology, University of California, Davis, California 95616 (C.A., A.J.M.)
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511 (C.R.B.)
- IA Watson Grains Research Centre, Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, Narrabri, New South Wales 2390, Australia (T.N.B.); and
- United States Department of Agriculture-Agricultural Research Service, Davis, California 95616 (A.J.M.)
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, 90095 (C.S., S.V.T., G.P.J., M.K.B., L.S.)
- Department of Biology, Utah State University, Logan, Utah 84322 (C.S.)
- Department of Viticulture and Enology, University of California, Davis, California 95616 (C.A., A.J.M.)
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511 (C.R.B.)
- IA Watson Grains Research Centre, Plant Breeding Institute, Sydney Institute of Agriculture, University of Sydney, Narrabri, New South Wales 2390, Australia (T.N.B.); and
- United States Department of Agriculture-Agricultural Research Service, Davis, California 95616 (A.J.M.)
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Scoffoni C, Albuquerque C, Brodersen CR, Townes SV, John GP, Cochard H, Buckley TN, McElrone AJ, Sack L. Leaf vein xylem conduit diameter influences susceptibility to embolism and hydraulic decline. New Phytol 2017; 213:1076-1092. [PMID: 27861926 DOI: 10.1111/nph.14256] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [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: 07/19/2016] [Accepted: 09/10/2016] [Indexed: 05/24/2023]
Abstract
Ecosystems worldwide are facing increasingly severe and prolonged droughts during which hydraulic failure from drought-induced embolism can lead to organ or whole plant death. Understanding the determinants of xylem failure across species is especially critical in leaves, the engines of plant growth. If the vulnerability segmentation hypothesis holds within leaves, higher order veins that are most terminal in the plant hydraulic system should be more susceptible to embolism to protect the rest of the water transport system. Increased vulnerability in the higher order veins would also be consistent with these experiencing the greatest tensions in the plant xylem network. To test this hypothesis, we combined X-ray micro-computed tomography imaging, hydraulic experiments, cross-sectional anatomy and 3D physiological modelling to investigate how embolisms spread throughout petioles and vein orders during leaf dehydration in relation to conduit dimensions. Decline of leaf xylem hydraulic conductance (Kx ) during dehydration was driven by embolism initiating in petioles and midribs across all species, and Kx vulnerability was strongly correlated with petiole and midrib conduit dimensions. Our simulations showed no significant impact of conduit collapse on Kx decline. We found xylem conduit dimensions play a major role in determining the susceptibility of the leaf water transport system during strong leaf dehydration.
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Affiliation(s)
- Christine Scoffoni
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
- Department of Biology, Utah State University, Logan, UT, 84322, USA
| | - Caetano Albuquerque
- Department of Viticulture and Enology, University of California, Davis, CA, 95616, USA
| | - Craig R Brodersen
- School of Forestry & Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT, 06511, USA
| | - Shatara V Townes
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
| | - Grace P John
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
| | - Hervé Cochard
- PIAF, INRA, Univ. Clermont-Auvergne, Clermont-Ferrand, 63100, France
| | - Thomas N Buckley
- Plant Breeding Institute, Faculty of Agriculture and Environment, The University of Sydney, 12656 Newell Hwy, Narrabri, NSW, 2390, Australia
| | - Andrew J McElrone
- Department of Viticulture and Enology, University of California, Davis, CA, 95616, USA
- USDA-Agricultural Research Service, Davis, CA, 95616, USA
| | - 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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Rodriguez-Dominguez CM, Buckley TN, Egea G, de Cires A, Hernandez-Santana V, Martorell S, Diaz-Espejo A. Most stomatal closure in woody species under moderate drought can be explained by stomatal responses to leaf turgor. Plant Cell Environ 2016; 39:2014-26. [PMID: 27255698 DOI: 10.1111/pce.12774] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [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: 02/22/2016] [Revised: 05/17/2016] [Accepted: 05/17/2016] [Indexed: 05/21/2023]
Abstract
Reduced stomatal conductance (gs ) during soil drought in angiosperms may result from effects of leaf turgor on stomata and/or factors that do not directly depend on leaf turgor, including root-derived abscisic acid (ABA) signals. To quantify the roles of leaf turgor-mediated and leaf turgor-independent mechanisms in gs decline during drought, we measured drought responses of gs and water relations in three woody species (almond, grapevine and olive) under a range of conditions designed to generate independent variation in leaf and root turgor, including diurnal variation in evaporative demand and changes in plant hydraulic conductance and leaf osmotic pressure. We then applied these data to a process-based gs model and used a novel method to partition observed declines in gs during drought into contributions from each parameter in the model. Soil drought reduced gs by 63-84% across species, and the model reproduced these changes well (r(2) = 0.91, P < 0.0001, n = 44) despite having only a single fitted parameter. Our analysis concluded that responses mediated by leaf turgor could explain over 87% of the observed decline in gs across species, adding to a growing body of evidence that challenges the root ABA-centric model of stomatal responses to drought.
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Affiliation(s)
- Celia M Rodriguez-Dominguez
- Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, 41012, Seville, Spain
- Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Seville, Spain
| | - Thomas N Buckley
- IA Watson Grains Research Centre, Plant Breeding Institute, Faculty of Agriculture and Environment, The University of Sydney, Narrabri, NSW, 2390, Australia
| | - Gregorio Egea
- Área de Ingeniería Agroforestal, Escuela Técnica Superior de Ingeniería Agronómica, Universidad de Sevilla, Ctra Utrera, km 1, 41013, Seville, Spain
| | - Alfonso de Cires
- Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Seville, Spain
| | - Virginia Hernandez-Santana
- Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, 41012, Seville, Spain
| | - Sebastia Martorell
- Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122, Palma, Illes Balears, Spain
| | - Antonio Diaz-Espejo
- Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, 41012, Seville, Spain
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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
| | - Thomas N Buckley
- IA Watson Grains Research Centre, Plant Breeding Institute, Faculty of Agriculture and Environment, The University of Sydney, Narrabri NSW 2390, Australia
| | - Christine Scoffoni
- 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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Abstract
Equations for stomatal density and maximum theoretical stomatal conductance as functions of stomatal initiation rate, epidermal cell size, and stomatal size enable scaling from development to flux.
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Affiliation(s)
- Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, California 90095 (L.S.); andPlant Breeding Institute, Faculty of Agriculture and Environment, The University of Sydney, Eveleigh, New South Wales 2015, Australia (T.N.B.)
| | - Thomas N Buckley
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, California 90095 (L.S.); andPlant Breeding Institute, Faculty of Agriculture and Environment, The University of Sydney, Eveleigh, New South Wales 2015, Australia (T.N.B.)
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Buckley TN. Stomatal responses to humidity: has the 'black box' finally been opened? Plant Cell Environ 2016; 39:482-4. [PMID: 26485479 DOI: 10.1111/pce.12651] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 10/12/2015] [Indexed: 05/22/2023]
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Poorter H, Jagodzinski AM, Ruiz‐Peinado R, Kuyah S, Luo Y, Oleksyn J, Usoltsev VA, Buckley TN, Reich PB, Sack L. How does biomass distribution change with size and differ among species? An analysis for 1200 plant species from five continents. New Phytol 2015; 208:736-749. [PMID: 26197869 PMCID: PMC5034769 DOI: 10.1111/nph.13571] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [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: 04/29/2015] [Accepted: 06/15/2015] [Indexed: 05/17/2023]
Abstract
We compiled a global database for leaf, stem and root biomass representing c. 11 000 records for c. 1200 herbaceous and woody species grown under either controlled or field conditions. We used this data set to analyse allometric relationships and fractional biomass distribution to leaves, stems and roots. We tested whether allometric scaling exponents are generally constant across plant sizes as predicted by metabolic scaling theory, or whether instead they change dynamically with plant size. We also quantified interspecific variation in biomass distribution among plant families and functional groups. Across all species combined, leaf vs stem and leaf vs root scaling exponents decreased from c. 1.00 for small plants to c. 0.60 for the largest trees considered. Evergreens had substantially higher leaf mass fractions (LMFs) than deciduous species, whereas graminoids maintained higher root mass fractions (RMFs) than eudicotyledonous herbs. These patterns do not support the hypothesis of fixed allometric exponents. Rather, continuous shifts in allometric exponents with plant size during ontogeny and evolution are the norm. Across seed plants, variation in biomass distribution among species is related more to function than phylogeny. We propose that the higher LMF of evergreens at least partly compensates for their relatively low leaf area : leaf mass ratio.
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Affiliation(s)
- Hendrik Poorter
- Plant Sciences (IBG‐2)Forschungszentrum Jülich GmbHD‐52425JülichGermany
| | - Andrzej M. Jagodzinski
- Polish Academy of SciencesInstitute of DendrologyParkowa 5KornikPL‐62‐035Poland
- Department of Game Management and Forest ProtectionFaculty of ForestryPoznan University of Life SciencesWojska Polskiego 71cPoznanPL‐60‐625Poland
| | - Ricardo Ruiz‐Peinado
- Departamento de Selvicultura y Gestión de Sistemas ForestalesINIA‐CIFORAvda. A Coruña, km 7.5.Madrid28040Spain
- Sustainable Forest Management Research InstituteUniversity of Valladolid‐INIAMadridSpain
| | - Shem Kuyah
- Jomo Kenyatta University of Agriculture and Technology (JKUAT)PO Box 62000Nairobi00200Kenya
| | - Yunjian Luo
- Department of EcologySchool of Horticulture and Plant ProtectionYangzhou University48 Wenhui East RoadYangzhou225009China
- State Key Laboratory of Urban and Regional EcologyResearch Centre for Eco‐Environmental SciencesChinese Academy of Sciences18 Shuangqing RoadHaidian DistrictBeijing100085China
| | - Jacek Oleksyn
- Polish Academy of SciencesInstitute of DendrologyParkowa 5KornikPL‐62‐035Poland
- Department of Forest ResourcesUniversity of Minnesota1530 Cleveland Ave NSt PaulMN55108USA
| | - Vladimir A. Usoltsev
- Ural State Forest Engineering UniversitySibirskiy Trakt 37Ekaterinburg620100Russia
- Botanical Garden of Ural Branch of Russian Academy of Sciencesul. Vos'mogo Marta 202aEkaterinburg620144Russia
| | - Thomas N. Buckley
- IA Watson Grains Research CentreFaculty of Agriculture and EnvironmentThe University of Sydney12656 Newell HighwayNarrabriNSWAustralia
| | - Peter B. Reich
- Department of Forest ResourcesUniversity of Minnesota1530 Cleveland Ave NSt PaulMN55108USA
- Hawkesbury Institute for the EnvironmentUniversity of Western SydneyLocked Bag 1797PenrithNSW2751Australia
| | - Lawren Sack
- Department of Ecology and EvolutionUniversity of California Los Angeles621 Charles E. Young Drive SouthLos AngelesCA90095USA
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