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Moser JG, Oberbauer SF, Sternberg LDSL, Ellsworth PZ, Starr G, Mortazavi B, Olivas PC. Water uptake of Alaskan tundra evergreens during the winter-spring transition. AMERICAN JOURNAL OF BOTANY 2016; 103:298-306. [PMID: 26823378 DOI: 10.3732/ajb.1500358] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 11/19/2015] [Indexed: 05/26/2023]
Abstract
PREMISE OF THE STUDY The cold season in the Arctic extends over 8 to 9 mo, yet little is known about vascular plant physiology during this period. Evergreen species photosynthesize under the snow, implying that they are exchanging water with the atmosphere. However, liquid water available for plant uptake may be limited at this time. The study objective was to determine whether evergreen plants are actively taking up water while under snow and/or immediately following snowmelt during spring thaw. METHODS In two in situ experiments, one at the plot level and another at the individual species level, (2)H-labeled water was used as a tracer injected beneath the snow, after which plant stems and leaves were tested for the presence of the label. In separate experiments, excised shoots of evergreen species were exposed to (2)H-labeled water for ∼5 s or 60 min and tested for foliar uptake of the label. KEY RESULTS In both the plot-level and the species-level experiments, some (2)H-labeled water was found in leaves and stems. Additionally, excised individual plant shoots exposed to labeled water for 60 min took up significantly more (2)H-label than shoots exposed ∼5 s. CONCLUSIONS Evergreen tundra plants take up water under snow cover, some via roots, but also likely by foliar uptake. The ability to take up water in the subnivean environment allows evergreen tundra plants to take advantage of mild spring conditions under the snow and replenish carbon lost by winter respiration.
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Affiliation(s)
- Jonathan G Moser
- Department of Biological Sciences, Florida International University 11200 SW 8th Street, Miami, Florida 33199 USA
| | - Steven F Oberbauer
- Department of Biological Sciences, Florida International University 11200 SW 8th Street, Miami, Florida 33199 USA
| | - Leonel da S L Sternberg
- Department of Biology, University of Miami, 215 Cox Science Center, 1301 Memorial Drive, Coral Gables, Florida 33124-0421 USA
| | - Patrick Z Ellsworth
- Department of Biology, University of Miami, 215 Cox Science Center, 1301 Memorial Drive, Coral Gables, Florida 33124-0421 USA
| | - Gregory Starr
- Department of Biological Sciences, University of Alabama, Box 870344, Tuscaloosa, Alabama 35487 USA
| | - Behzad Mortazavi
- Dauphin Island Sea Laboratory, 101 Bienville Boulevard, Dauphin Island, Alabama 36528 USA
| | - Paulo C Olivas
- Department of Biological Sciences, Florida International University 11200 SW 8th Street, Miami, Florida 33199 USA
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102
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Yin J, Fridley JD, Smith MS, Bauerle TL. Xylem vessel traits predict the leaf phenology of native and non‐native understorey species of temperate deciduous forests. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12476] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jingjing Yin
- School of Integrative Plant Science Cornell University 134A Plant Science Bldg Ithaca NY 14853 USA
| | - Jason D. Fridley
- Department of Biology 448 Life Science Complex Syracuse University Syracuse NY 13244 USA
| | - Maria S. Smith
- School of Integrative Plant Science Cornell University 134A Plant Science Bldg Ithaca NY 14853 USA
| | - Taryn L. Bauerle
- School of Integrative Plant Science Cornell University 134A Plant Science Bldg Ithaca NY 14853 USA
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103
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Schreiber SG, Hacke UG, Chamberland S, Lowe CW, Kamelchuk D, Bräutigam K, Campbell MM, Thomas BR. Leaf size serves as a proxy for xylem vulnerability to cavitation in plantation trees. PLANT, CELL & ENVIRONMENT 2016; 39:272-81. [PMID: 26177991 DOI: 10.1111/pce.12611] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 06/26/2015] [Accepted: 06/30/2015] [Indexed: 05/08/2023]
Abstract
Hybrid poplars are an important renewable forest resource known for their high productivity. At the same time, they are highly vulnerable to water stress. Identifying traits that can serve as indicators for growth performance remains an important task, particularly under field conditions. Understanding which trait combinations translate to improved productivity is key in order to satisfy the demand for poplar wood in an uncertain future climate. In this study, we compared hydraulic and leaf traits among five hybrid poplar clones at 10 plantations in central Alberta. We also assessed the variation of these traits between 2- to 3-year-old branches from the lower to mid-crown and current-year long shoots from the mid to upper crown. Our results showed that (1) hybrid poplars differed in key hydraulic parameters between branch type, (2) variation of hydraulic traits among clones was relatively large for some clones and less for others, and (3) strong relationships between measured hydraulic traits, such as vessel diameter, cavitation resistance, xylem-specific and leaf-specific conductivity and leaf area, were observed. Our results suggest that leaf size could serve as an additional screening tool when selecting for drought-tolerant genotypes in forest management and tree improvement programmes.
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Affiliation(s)
- Stefan G Schreiber
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, Alberta, Canada, T6G 2E3
| | - Uwe G Hacke
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, Alberta, Canada, T6G 2E3
| | - Sabrina Chamberland
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, Alberta, Canada, T6G 2E3
| | - Christopher W Lowe
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, Alberta, Canada, T6G 2E3
| | - David Kamelchuk
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, Alberta, Canada, T6G 2E3
| | - Katharina Bräutigam
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada, M1C 1A4
| | - Malcolm M Campbell
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada, M1C 1A4
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, 25 Willcocks St., Toronto, Ontario, Canada, M5S 3B2
- Department of Molecular and Cellular Biology, University of Guelph, Summerlee Science Complex, Guelph, Ontario, Canada, N1G 2W1
| | - Barb R Thomas
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, Alberta, Canada, T6G 2E3
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104
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Charra-Vaskou K, Badel E, Charrier G, Ponomarenko A, Bonhomme M, Foucat L, Mayr S, Améglio T. Cavitation and water fluxes driven by ice water potential in Juglans regia during freeze-thaw cycles. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:739-50. [PMID: 26585223 PMCID: PMC4737071 DOI: 10.1093/jxb/erv486] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Freeze-thaw cycles induce major hydraulic changes due to liquid-to-ice transition within tree stems. The very low water potential at the ice-liquid interface is crucial as it may cause lysis of living cells as well as water fluxes and embolism in sap conduits, which impacts whole tree-water relations. We investigated water fluxes induced by ice formation during freeze-thaw cycles in Juglans regia L. stems using four non-invasive and complementary approaches: a microdendrometer, magnetic resonance imaging, X-ray microtomography, and ultrasonic acoustic emissions analysis. When the temperature dropped, ice nucleation occurred, probably in the cambium or pith areas, inducing high water potential gradients within the stem. The water was therefore redistributed within the stem toward the ice front. We could thus observe dehydration of the bark's living cells leading to drastic shrinkage of this tissue, as well as high tension within wood conduits reaching the cavitation threshold in sap vessels. Ultrasonic emissions, which were strictly emitted only during freezing, indicated cavitation events (i.e. bubble formation) following ice formation in the xylem sap. However, embolism formation (i.e. bubble expansion) in stems was observed only on thawing via X-ray microtomography for the first time on the same sample. Ultrasonic emissions were detected during freezing and were not directly related to embolism formation. These results provide new insights into the complex process and dynamics of water movements and ice formation during freeze-thaw cycles in tree stems.
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Affiliation(s)
- Katline Charra-Vaskou
- INRA, UMR PIAF, F-63100 Clermont-Ferrand, France Clermont Université, Blaise Pascal University, UMR PIAF, F-63100 Clermont-Ferrand, France
| | - Eric Badel
- INRA, UMR PIAF, F-63100 Clermont-Ferrand, France Clermont Université, Blaise Pascal University, UMR PIAF, F-63100 Clermont-Ferrand, France
| | - Guillaume Charrier
- Department of Botany, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Alexandre Ponomarenko
- INRA, UMR PIAF, F-63100 Clermont-Ferrand, France Clermont Université, Blaise Pascal University, UMR PIAF, F-63100 Clermont-Ferrand, France
| | - Marc Bonhomme
- INRA, UMR PIAF, F-63100 Clermont-Ferrand, France Clermont Université, Blaise Pascal University, UMR PIAF, F-63100 Clermont-Ferrand, France
| | | | - Stefan Mayr
- Department of Botany, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Thierry Améglio
- INRA, UMR PIAF, F-63100 Clermont-Ferrand, France Clermont Université, Blaise Pascal University, UMR PIAF, F-63100 Clermont-Ferrand, France
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105
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106
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Zwieniecki MA, Secchi F. Threats to xylem hydraulic function of trees under 'new climate normal' conditions. PLANT, CELL & ENVIRONMENT 2015; 38:1713-24. [PMID: 25039674 DOI: 10.1111/pce.12412] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 07/02/2014] [Accepted: 07/06/2014] [Indexed: 05/23/2023]
Abstract
Climate models predict increases in frequency and intensity of extreme environmental conditions, such as changes to minimum and maximum temperatures, duration of drought periods, intensity of rainfall/snowfall events and wind strength. These local extremes, rather than average climatic conditions, are closely linked to woody plant survival, as trees cope with such events over long lifespans. While the xylem provides trees with structural strength and is considered the most robust part of a tree's structure, it is also the most physiologically vulnerable as tree survival depends on its ability to sustain water supply to the tree crown under variable environmental conditions. Many structural, functional and biological tree properties evolved to protect xylem from loss of transport function because of embolism or to restore xylem transport capacity following embolism formation. How 'the new climate normal' conditions will affect these evolved strategies is yet to be seen. Our understanding of xylem physiology and current conceptual models describing embolism formation and plant recovery from water stress, however, can provide insight into near-future challenges that woody plants will face. In addition, knowledge of species-specific properties of xylem function may help guide mitigation of climate change impacts on woody plants in natural and agricultural tree communities.
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Affiliation(s)
- Maciej A Zwieniecki
- Department of Plant Sciences, University of California - Davis, Davis, CA, 95616, USA
| | - Francesca Secchi
- Department of Plant Sciences, University of California - Davis, Davis, CA, 95616, USA
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107
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Charrier G, Pramsohler M, Charra‐Vaskou K, Saudreau M, Améglio T, Neuner G, Mayr S. Ultrasonic emissions during ice nucleation and propagation in plant xylem. THE NEW PHYTOLOGIST 2015; 207:570-8. [PMID: 25756189 PMCID: PMC5024006 DOI: 10.1111/nph.13361] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 02/10/2015] [Indexed: 05/09/2023]
Abstract
Ultrasonic acoustic emission analysis enables nondestructive monitoring of damage in dehydrating or freezing plant xylem. We studied acoustic emissions (AE) in freezing stems during ice nucleation and propagation, by combining acoustic and infrared thermography techniques and controlling the ice nucleation point. Ultrasonic activity in freezing samples of Picea abies showed two distinct phases: the first on ice nucleation and propagation (up to 50 AE s(-1) ; reversely proportional to the distance to ice nucleation point), and the second (up to 2.5 AE s(-1) ) after dissipation of the exothermal heat. Identical patterns were observed in other conifer and angiosperm species. The complex AE patterns are explained by the low water potential of ice at the ice-liquid interface, which induced numerous and strong signals. Ice propagation velocities were estimated via AE (during the first phase) and infrared thermography. Acoustic activity ceased before the second phase probably because the exothermal heating and the volume expansion of ice caused decreasing tensions. Results indicate cavitation events at the ice front leading to AE. Ultrasonic emission analysis enabled new insights into the complex process of xylem freezing and might be used to monitor ice propagation in natura.
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Affiliation(s)
- Guillaume Charrier
- Department of BotanyUniversity of InnsbruckSternwartestrasse. 15A‐6020InnsbruckAustria
| | - Manuel Pramsohler
- Department of BotanyUniversity of InnsbruckSternwartestrasse. 15A‐6020InnsbruckAustria
| | - Katline Charra‐Vaskou
- INRAUMR547 PIAFF‐63100Clermont‐FerrandFrance
- Clermont UniversitéUniversité Blaise PascalUMR547 PIAFF‐63100Clermont‐FerrandFrance
| | - Marc Saudreau
- INRAUMR547 PIAFF‐63100Clermont‐FerrandFrance
- Clermont UniversitéUniversité Blaise PascalUMR547 PIAFF‐63100Clermont‐FerrandFrance
| | - Thierry Améglio
- INRAUMR547 PIAFF‐63100Clermont‐FerrandFrance
- Clermont UniversitéUniversité Blaise PascalUMR547 PIAFF‐63100Clermont‐FerrandFrance
| | - Gilbert Neuner
- Department of BotanyUniversity of InnsbruckSternwartestrasse. 15A‐6020InnsbruckAustria
| | - Stefan Mayr
- Department of BotanyUniversity of InnsbruckSternwartestrasse. 15A‐6020InnsbruckAustria
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108
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Knipfer T, Brodersen CR, Zedan A, Kluepfel DA, McElrone AJ. Patterns of drought-induced embolism formation and spread in living walnut saplings visualized using X-ray microtomography. TREE PHYSIOLOGY 2015; 35:744-55. [PMID: 26063708 DOI: 10.1093/treephys/tpv040] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 04/27/2015] [Indexed: 05/23/2023]
Abstract
Embolism formation and spread are dependent on conduit structure and xylem network connectivity. Detailed spatial analysis has been limited due to a lack of non-destructive methods to visualize these processes in living plants. We used synchrotron X-ray computed tomography (microCT) to visualize these processes in vivo for Juglans microcarpa Berl. saplings subjected to drought, and also evaluated embolism repair capability after re-watering. Cavitation was not detected in vivo until stem water potentials (Ψ(stem)) reached -2.2 MPa, and loss of stem hydraulic conductivity as derived from microCT images predicted that 50% of conductivity was lost at Ψ(stem) of ∼ -3.5 MPa; xylem vulnerability as determined with the centrifuge method was comparable only in the range of Ψ(stem) from -2.5 to -3.5 MPa. MicroCT images showed that cavitation appeared initially in isolated vessels not connected to other air-filled conduits. Once embolized vessels were present, multiple vessels in close proximity cavitated, and 3-D analysis along the stem axis revealed some connections between cavitated vessels. A tomography-derived automated xylem network analysis found that only 36% of vessels had one or more connections to other vessels. Cavitation susceptibility was related to vessel diameter, with large diameter vessels (>40 μm, mean diameter 25-30 μm) cavitating mainly under moderate stress (Ψ(stem) > -3 MPa) and small diameter vessels (<30 μm) under severe stress. After re-watering there was no evidence for short or longer term vessel refilling over 2 weeks despite a rapid recovery of plant water status. The low embolism susceptibility in 1-year-old J. microcarpa may aid sapling survival during establishment.
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Affiliation(s)
- Thorsten Knipfer
- Department of Viticulture and Enology, University of California, Davis, CA 95616, USA
| | - Craig R Brodersen
- School of Forestry and Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT 06511, USA
| | - Amr Zedan
- Department of Viticulture and Enology, University of California, Davis, CA 95616, USA
| | - Daniel A Kluepfel
- US Department of Agriculture, Agricultural Research Service, Davis, CA 95616, USA
| | - Andrew J McElrone
- Department of Viticulture and Enology, University of California, Davis, CA 95616, USA US Department of Agriculture, Agricultural Research Service, Davis, CA 95616, USA
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109
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Venturas MD, Mackinnon ED, Jacobsen AL, Pratt RB. Excising stem samples underwater at native tension does not induce xylem cavitation. PLANT, CELL & ENVIRONMENT 2015; 38:1060-8. [PMID: 25292257 DOI: 10.1111/pce.12461] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 09/25/2014] [Indexed: 05/10/2023]
Abstract
Xylem resistance to water stress-induced cavitation is an important trait that is associated with drought tolerance of plants. The level of xylem cavitation experienced by a plant is often assessed as the percentage loss in conductivity (PLC) at different water potentials. Such measurements are constructed with samples that are excised underwater at native tensions. However, a recent study concluded that cutting conduits under significant tension induced cavitation, even when samples were held underwater during cutting. This resulted in artificially increased PLC because of what we have termed a 'tension-cutting artefact'. We tested the hypothesized tension-cutting artefact on five species by measuring PLC at native tension compared with after xylem tensions had been relaxed. Our results did not support the tension-cutting artefact hypothesis, as no differences were observed between native and relaxed samples in four of five species. In a fifth species (Laurus nobilis), differences between native and relaxed samples appear to be due to vessel refilling rather than a tension-cutting effect. We avoided the tension-cutting artefact by cutting samples to slightly longer than their measurement length and subsequent trimming of at least 0.5 cm of sample ends prior to measurement.
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Affiliation(s)
- Martin D Venturas
- Department of Biology, California State University, Bakersfield, 9001 Stockdale Hwy, Bakersfield, CA, 93311, USA
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110
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Feng F, Ding F, Tyree MT. Investigations concerning cavitation and frost fatigue in clonal 84K poplar using high-resolution cavitron measurements. PLANT PHYSIOLOGY 2015; 168:144-55. [PMID: 25786827 PMCID: PMC4424019 DOI: 10.1104/pp.114.256271] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 03/17/2015] [Indexed: 05/17/2023]
Abstract
Both drought and freezing-thawing of stems induce a loss of hydraulic conductivity (percentage loss of conductivity [PLC]) in woody plants. Drought-induced PLC is often accompanied by physical damage to pit membranes, causing a shift in vulnerability curves (cavitation fatigue). Hence, if cavitated stems are flushed to remove embolisms, the next vulnerability curve is different (shifted to lower tensions). The 84K poplar (Populus alba × Populus glandulosa) clone has small vessels that should be immune from frost-induced PLC, but results demonstrated that freezing-thawing in combination with tension synergistically increased PLC. Frost fatigue has already been defined, which is similar to cavitation fatigue but induced by freezing. Frost fatigue caused a transition from a single to a dual Weibull curve, but drought-fatigued stems had single Weibull curves shifted to lower tensions. Studying the combined impact of tension plus freezing on fatigue provided evidence that the mechanism of frost fatigue may be the extra water tension induced by freezing or thawing while spinning stems in a centrifuge rather than direct ice damage. A hypothesis is advanced that tension is enhanced as ice crystals grow or melt during the freeze or thaw event, respectively, causing a nearly identical fatigue event to that induced by drought.
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Affiliation(s)
- Feng Feng
- College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Fei Ding
- College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Melvin T Tyree
- College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China
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111
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Charrier G, Ngao J, Saudreau M, Améglio T. Effects of environmental factors and management practices on microclimate, winter physiology, and frost resistance in trees. FRONTIERS IN PLANT SCIENCE 2015; 6:259. [PMID: 25972877 PMCID: PMC4411886 DOI: 10.3389/fpls.2015.00259] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Accepted: 04/01/2015] [Indexed: 05/02/2023]
Abstract
Freezing stress is one of the most important limiting factors determining the ecological distribution and production of tree species. Assessment of frost risk is, therefore, critical for forestry, fruit production, and horticulture. Frost risk is substantial when hazard (i.e., exposure to damaging freezing temperatures) intersects with vulnerability (i.e., frost sensitivity). Based on a large number of studies on frost resistance and frost occurrence, we highlight the complex interactive roles of environmental conditions, carbohydrates, and water status in frost risk development. To supersede the classical empirical relations used to model frost hardiness, we propose an integrated ecophysiologically-based framework of frost risk assessment. This framework details the individual or interactive roles of these factors, and how they are distributed in time and space at the individual-tree level (within-crown and across organs). Based on this general framework, we are able to highlight factors by which different environmental conditions (e.g., temperature, light, flood, and drought), and management practices (pruning, thinning, girdling, sheltering, water aspersion, irrigation, and fertilization) influence frost sensitivity and frost exposure of trees.
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Affiliation(s)
| | - Jérôme Ngao
- INRA, Clermont-Ferrand, France
- Clermont Université, Université Blaise Pascal, Clermont-Ferrand, France
| | - Marc Saudreau
- INRA, Clermont-Ferrand, France
- Clermont Université, Université Blaise Pascal, Clermont-Ferrand, France
| | - Thierry Améglio
- INRA, Clermont-Ferrand, France
- Clermont Université, Université Blaise Pascal, Clermont-Ferrand, France
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112
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Schreiber SG, Hacke UG, Hamann A. Variation of xylem vessel diameters across a climate gradient: insight from a reciprocal transplant experiment with a widespread boreal tree. Funct Ecol 2015. [DOI: 10.1111/1365-2435.12455] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Stefan G. Schreiber
- Department of Renewable Resources University of Alberta 442 Earth Sciences Building Edmonton ABT6G 2E3 Canada
| | - Uwe G. Hacke
- Department of Renewable Resources University of Alberta 442 Earth Sciences Building Edmonton ABT6G 2E3 Canada
| | - Andreas Hamann
- Department of Renewable Resources University of Alberta 442 Earth Sciences Building Edmonton ABT6G 2E3 Canada
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113
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Kasuga J, Charrier G, Uemura M, Améglio T. Characteristics of ultrasonic acoustic emissions from walnut branches during freeze-thaw-induced embolism formation. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:1965-75. [PMID: 25662846 PMCID: PMC4669555 DOI: 10.1093/jxb/eru543] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Ultrasonic acoustic emission (UAE) methods have been applied for the detection of freeze-thaw-induced embolism formation in water conduits of tree species. Until now, however, the exact source(s) of UAE has not been identified especially in angiosperm species, in which xylem tissues are composed of diverse types of cells. In this study, UAE was recorded from excised branches of walnut (Juglans regia cv. Franquette) during freeze-thaw cycles, and attempts were made to characterize UAEs generated by cavitation events leading to embolism formation according to their properties. During freeze-thaw cycles, a large number of UAEs were generated from the sample segments. However, the cumulative numbers of total UAE during freeze-thawing were not correlated with the percentage loss of hydraulic conductivity after thawing, suggesting that the sources of UAE were not only cavitation leading to embolism formation in vessels. Among the UAEs, cumulative numbers of UAEs with absolute energy >10.0 fJ strongly correlated with the increase in percentage loss of hydraulic conductivity. The high absolute energy of the UAEs might reflect the formation of large bubbles in the large lumen of vessels. Therefore, UAEs generated by cavitation events in vessels during freeze-thawing might be distinguished from other signals according to their magnitudes of absolute energy. On the other hand, the freezing of xylem parenchyma cells was followed by a certain number of UAEs. These results indicate the possibility that UAE methods can be applied to the detection of both freeze-thaw-induced embolism and supercooling breakdown in parenchyma cells in xylem.
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Affiliation(s)
- Jun Kasuga
- Institut National de la Recherche Agronomique, UMR 547 PIAF, F-63100 Clermont-Ferrand, France Clermont Université, Université Blaise Pascal, UMR 547 PIAF, F-63100 Clermont-Ferrand, France Department of Agro-Environmental Science, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan
| | - Guillaume Charrier
- Institut National de la Recherche Agronomique, UMR 547 PIAF, F-63100 Clermont-Ferrand, France Clermont Université, Université Blaise Pascal, UMR 547 PIAF, F-63100 Clermont-Ferrand, France Department of Botany, University of Innsbruck, A-6020 Innsbruck, Austria
| | - Matsuo Uemura
- Cryobiofrontier Research Center, Faculty of Agriculture, Iwate University, Morioka 020-8550, Japan
| | - Thierry Améglio
- Institut National de la Recherche Agronomique, UMR 547 PIAF, F-63100 Clermont-Ferrand, France Clermont Université, Université Blaise Pascal, UMR 547 PIAF, F-63100 Clermont-Ferrand, France
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114
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Hochberg U, Degu A, Gendler T, Fait A, Rachmilevitch S. The variability in the xylem architecture of grapevine petiole and its contribution to hydraulic differences. FUNCTIONAL PLANT BIOLOGY : FPB 2015; 42:357-365. [PMID: 32480680 DOI: 10.1071/fp14167] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 11/09/2014] [Indexed: 05/27/2023]
Abstract
Grapevine cultivars possess large variability in their response to water availability, and are therefore considered as a good model to study plant hydraulic adjustments. The current research compared the petiole anatomy of two grapevine (Vitis vinifera L.) cultivars, Shiraz and Cabernet Sauvignon, in respect to hydraulic properties. Hydraulic differences between the cultivar petioles were tested over 3 years (2011-2013). Anatomical differences, hydraulic conductivity and embolism were tested under terminal drought conditions. Additionally, xylem differentiation under well watered (WW) and water deficit (WD) conditions was compared. Shiraz was shown to possess larger xylem vessels that resulted in a significantly higher theoretical specific hydraulic conductivity (Kts), leaf hydraulic conductivity (Kleaf) and maximal petiole hydraulic conductivity (Kpetiole). Under WD, smaller vessels were developed, more noticeably in Shiraz. Results confirmed a link between petiole hydraulic architecture and hydraulic behaviour, providing a simple mechanistic explanation for the higher transpiration rates commonly measured in Shiraz. Smaller xylem vessels in Cabernet Sauvignon could imply on its adaptation to WD, and explains its better performances under such conditions.
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Affiliation(s)
- Uri Hochberg
- Albert Katz International School, Beer-Sheva, Israel
| | - Asfaw Degu
- Albert Katz International School, Beer-Sheva, Israel
| | - Tanya Gendler
- The French Associates Institute for Agriculture and Biotechnology of Drylands (FAAB), the Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, 84990 Sede Boqer, Israel
| | - Aaron Fait
- The French Associates Institute for Agriculture and Biotechnology of Drylands (FAAB), the Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, 84990 Sede Boqer, Israel
| | - Shimon Rachmilevitch
- The French Associates Institute for Agriculture and Biotechnology of Drylands (FAAB), the Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, 84990 Sede Boqer, Israel
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115
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Community dynamics over 14 years along gradients of geological substrate and topography in tropical montane forests on Mount Kinabalu, Borneo. JOURNAL OF TROPICAL ECOLOGY 2015. [DOI: 10.1017/s0266467414000777] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Abstract:To understand the variation in community dynamics of tropical montane forests along gradients of soil fertility, death, recruitment and growth of trees (≥5 cm diameter) were monitored over 14 y (1997–2011) in nine plots placed in a matrix of three geological substrate types (Quaternary sediments, Tertiary sedimentary rocks and ultrabasic rocks) and three topographical units (ridge, middle and lower slopes) on Mount Kinabalu, Borneo. The plot area was 0.05 ha for ridge, 0.1 ha for middle slope and 0.2 ha (on ultrabasic rocks) and 1 ha (on the other substrates) for lower slope. Recruitment rates did not show a consistent pattern across geological substrates or topographies. Mortality rates were relatively high in almost all plots during the 1997–1999 period, including the El Niño drought, and in three plots on ultrabasic rocks during 2001–2005. Binomial logistic regression analyses showed that mortality during 1997–1999 increased with soil fertility (soluble phosphorus). Background mortality, excluding these periods, did not differ across geological substrates or topographies. The average growth rate during 1997–2011 was higher on more fertile soils and positively correlated with mortality during 1997–1999. We suggest that a high mortality rate during the drought period was related to high species diversity on more fertile soils, whereas a lower growth rate was related to stunted structures on poorer soils.
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116
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Badel E, Ewers FW, Cochard H, Telewski FW. Acclimation of mechanical and hydraulic functions in trees: impact of the thigmomorphogenetic process. FRONTIERS IN PLANT SCIENCE 2015; 6:266. [PMID: 25954292 PMCID: PMC4406077 DOI: 10.3389/fpls.2015.00266] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 04/03/2015] [Indexed: 05/05/2023]
Abstract
The secondary xylem (wood) of trees mediates several functions including water transport and storage, mechanical support and storage of photosynthates. The optimal structures for each of these functions will most likely differ. The complex structure and function of xylem could lead to trade-offs between conductive efficiency, resistance to embolism, and mechanical strength needed to count for mechanical loading due to gravity and wind. This has been referred to as the trade-off triangle, with the different optimal solutions to the structure/function problems depending on the environmental constraints as well as taxonomic histories. Thus, the optimisation of each function will lead to drastically different anatomical structures. Trees are able to acclimate the internal structure of their trunk and branches according to the stress they experience. These acclimations lead to specific structures that favor the efficiency or the safety of one function but can be antagonistic with other functions. Currently, there are no means to predict the way a tree will acclimate or optimize its internal structure in support of its various functions under differing environmental conditions. In this review, we will focus on the acclimation of xylem anatomy and its resulting mechanical and hydraulic functions to recurrent mechanical strain that usually result from wind-induced thigmomorphogenesis with a special focus on the construction cost and the possible trade-off between wood functions.
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Affiliation(s)
- Eric Badel
- INRA, UMR 547 PIAF, Clermont-FerrandFrance
- Clermont Université–Université Blaise-Pascal, UMR 547 PIAF, Clermont-FerrandFrance
- *Correspondence: Eric Badel, INRA, UMR 547 PIAF, 63100 Clermont-Ferrand, France; Clermont Université–Université Blaise-Pascal, UMR 547 PIAF, 63000 Clermont-Ferrand, France
| | - Frank W. Ewers
- Department of Biological Sciences, California State Polytechnic UniversityPomona, CA, USA
| | - Hervé Cochard
- INRA, UMR 547 PIAF, Clermont-FerrandFrance
- Clermont Université–Université Blaise-Pascal, UMR 547 PIAF, Clermont-FerrandFrance
| | - Frank W. Telewski
- Department of Plant Biology, Michigan State UniversityEast Lansing, MI, USA
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117
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Hacke UG, Venturas MD, MacKinnon ED, Jacobsen AL, Sperry JS, Pratt RB. The standard centrifuge method accurately measures vulnerability curves of long-vesselled olive stems. THE NEW PHYTOLOGIST 2015; 205:116-27. [PMID: 25229841 DOI: 10.1111/nph.13017] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 08/01/2014] [Indexed: 05/02/2023]
Abstract
The standard centrifuge method has been frequently used to measure vulnerability to xylem cavitation. This method has recently been questioned. It was hypothesized that open vessels lead to exponential vulnerability curves, which were thought to be indicative of measurement artifact. We tested this hypothesis in stems of olive (Olea europea) because its long vessels were recently claimed to produce a centrifuge artifact. We evaluated three predictions that followed from the open vessel artifact hypothesis: shorter stems, with more open vessels, would be more vulnerable than longer stems; standard centrifuge-based curves would be more vulnerable than dehydration-based curves; and open vessels would cause an exponential shape of centrifuge-based curves. Experimental evidence did not support these predictions. Centrifuge curves did not vary when the proportion of open vessels was altered. Centrifuge and dehydration curves were similar. At highly negative xylem pressure, centrifuge-based curves slightly overestimated vulnerability compared to the dehydration curve. This divergence was eliminated by centrifuging each stem only once. The standard centrifuge method produced accurate curves of samples containing open vessels, supporting the validity of this technique and confirming its utility in understanding plant hydraulics. Seven recommendations for avoiding artefacts and standardizing vulnerability curve methodology are provided.
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Affiliation(s)
- Uwe G Hacke
- Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G 2E3, Canada
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118
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Muller O, Stewart JJ, Cohu CM, Polutchko SK, Demmig-Adams B, Adams WW. Leaf architectural, vascular and photosynthetic acclimation to temperature in two biennials. PHYSIOLOGIA PLANTARUM 2014; 152:763-72. [PMID: 24818515 DOI: 10.1111/ppl.12226] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 04/07/2014] [Accepted: 04/08/2014] [Indexed: 05/03/2023]
Abstract
Acclimation of leaf features to growth temperature was investigated in two biennials (whose life cycle spans summer and winter seasons) using different mechanisms of sugar loading into exporting conduits, Verbascum phoeniceum (employs sugar-synthesizing enzymes driving symplastic loading through plasmodesmatal wall pores of phloem cells) and Malva neglecta (likely apoplastic loader transporting sugar via membrane transport proteins of phloem cells). In both species, acclimation to lower temperature involved greater maximal photosynthesis rates and vein density per leaf area in close correlation with modification of minor vein cellular features. While the symplastically loading biennial exhibited adjustments in the size of minor leaf vein cells (consistent with adjustment of the level of sugar-synthesizing enzymes), the putative apoplastic biennial exhibited adjustments in the number of cells (consistent with adjustment of cell membrane area for transporter placement). This upregulation of morphological and anatomical features at lower growth temperature likely contributes to the success of both the species during the winter. Furthermore, while acclimation to low temperature involved greater leaf mass per area in both species, this resulted from greater leaf thickness in V. phoeniceum vs a greater number of mesophyll cells per leaf area in M. neglecta. Both types of adjustments presumably accommodate more chloroplasts per leaf area contributing to photosynthesis. Both biennials exhibited high foliar vein densities (particularly the solar-tracking M. neglecta), which should aid both sugar export from and delivery of water to the leaves.
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Affiliation(s)
- Onno Muller
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
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119
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Lintunen A, Lindfors L, Kolari P, Juurola E, Nikinmaa E, Hölttä T. Bursts of CO2 released during freezing offer a new perspective on avoidance of winter embolism in trees. ANNALS OF BOTANY 2014; 114:1711-8. [PMID: 25252688 PMCID: PMC4649691 DOI: 10.1093/aob/mcu190] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 08/13/2014] [Indexed: 05/12/2023]
Abstract
BACKGROUND AND AIMS Woody plants can suffer from winter embolism as gas bubbles are formed in the water-conducting conduits when freezing occurs: gases are not soluble in ice, and the bubbles may expand and fill the conduits with air during thawing. A major assumption usually made in studies of winter embolism formation is that all of the gas dissolved in the xylem sap is trapped within the conduits and forms bubbles during freezing. The current study tested whether this assumption is actually valid, or whether efflux of gases from the stem during freezing reduces the occurrence of embolism. METHODS CO2 efflux measurements were conducted during freezing experiments for saplings of three Scots pine (Pinus sylvestris) and three Norway spruce (Picea abies) trees under laboratory conditions, and the magnitudes of the freezing-related bursts of CO2 released from the stems were analysed using a previously published mechanistic model of CO2 production, storage, diffusion and efflux from a tree stem. The freezing-related bursts of CO2 released from a mature Scots pine tree growing in field conditions were also measured and analysed. KEY RESULTS Substantial freezing-related bursts of CO2 released from the stem were found to occur during both the laboratory experiments and under field conditions. In the laboratory, the fraction of CO2 released from the stem ranged between 27 and 96 % of the total CO2 content within the stem. CONCLUSIONS All gases dissolved in the xylem sap are not trapped within the ice in the stem during freezing, as has previously been assumed, thus adding a new dimension to the understanding of winter embolism formation. The conduit water volume not only determines the volume of bubbles formed during freezing, but also the efficiency of gas efflux out of the conduit during the freezing process.
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Affiliation(s)
- A Lintunen
- Department of Forest Sciences, University of Helsinki, Post Office Box 27, FI-00014, Helsinki, Finland
| | - L Lindfors
- Department of Forest Sciences, University of Helsinki, Post Office Box 27, FI-00014, Helsinki, Finland Department of Physics, University of Helsinki, Post Office Box 64, FI-00014, Helsinki, Finland
| | - P Kolari
- Department of Forest Sciences, University of Helsinki, Post Office Box 27, FI-00014, Helsinki, Finland Department of Physics, University of Helsinki, Post Office Box 64, FI-00014, Helsinki, Finland
| | - E Juurola
- Department of Forest Sciences, University of Helsinki, Post Office Box 27, FI-00014, Helsinki, Finland Department of Physics, University of Helsinki, Post Office Box 64, FI-00014, Helsinki, Finland
| | - E Nikinmaa
- Department of Forest Sciences, University of Helsinki, Post Office Box 27, FI-00014, Helsinki, Finland
| | - T Hölttä
- Department of Forest Sciences, University of Helsinki, Post Office Box 27, FI-00014, Helsinki, Finland
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120
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Thompson KA, Husband BC, Maherali H. Climatic niche differences between diploid and tetraploid cytotypes of Chamerion angustifolium (Onagraceae). AMERICAN JOURNAL OF BOTANY 2014; 101:1868-75. [PMID: 25366852 DOI: 10.3732/ajb.1400184] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
PREMISE OF THE STUDY Polyploidy-the possession of more than two copies of each chromosome in the nucleus-is common in flowering plants. Polyploid plants can occupy different geographic ranges than their diploid progenitors, but the factors responsible for maintaining these range differences are poorly understood. Polyploidy can have significant physiological consequences, and the present study aims to determine whether previously described physiological differences between cytotypes are correlated with climatic niches and geographic distributions. METHODS Prior research indicates that tetraploid plants of Chamerion angustifolium (Onagraceae) are more tolerant of drought and less tolerant of freezing than diploids, which suggests that they should occupy a niche that is warmer and drier than that of diploids. We extracted climate data for 134 populations of C. angustifolium classified as pure diploid, pure tetraploid, or mixed-ploidy. We compared climatic conditions between these population categories and generated ecological niche models to compare their geographic distribution with prior qualitative estimates. KEY RESULTS Pure tetraploid populations occupy habitats that are warmer and drier than those of pure diploid populations. Mixed-ploidy populations occur in habitats that are not strictly intermediate between pure diploid and pure tetraploid populations, but are as cold as pure diploid populations and have intermediate soil moisture deficits. Our niche models were similar to previous qualitative estimates of cytotype geographic distribution. CONCLUSIONS The correspondence between the physiological tolerances of cytotypes, their climatic niches, and their geographic distributions suggests that physiological traits are at least partially responsible for differences in the realized climatic niches of diploid and tetraploid C. angustifolium.
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Affiliation(s)
- Ken A Thompson
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Brian C Husband
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Hafiz Maherali
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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121
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Wood anatomy reveals high theoretical hydraulic conductivity and low resistance to vessel implosion in a Cretaceous fossil forest from northern Mexico. PLoS One 2014; 9:e108866. [PMID: 25279992 PMCID: PMC4184822 DOI: 10.1371/journal.pone.0108866] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 08/27/2014] [Indexed: 11/29/2022] Open
Abstract
The Olmos Formation (upper Campanian), with over 60 angiosperm leaf morphotypes, is Mexico's richest Cretaceous flora. Paleoclimate leaf physiognomy estimates indicate that the Olmos paleoforest grew under wet and warm conditions, similar to those present in modern tropical rainforests. Leaf surface area, tree size and climate reconstructions suggest that this was a highly productive system. Efficient carbon fixation requires hydraulic efficiency to meet the evaporative demands of the photosynthetic surface, but it comes at the expense of increased risk of drought-induced cavitation. Here we tested the hypothesis that the Olmos paleoforest had high hydraulic efficiency, but was prone to cavitation. We characterized the hydraulic properties of the Olmos paleoforest using theoretical conductivity (Ks), vessel composition (S) and vessel fraction (F), and measured drought resistance using vessel implosion resistance and the water potential at which there is 50% loss of hydraulic conductivity (P50). We found that the Olmos paleoforest had high hydraulic efficiency, similar to that present in several extant tropical-wet or semi-deciduous forest communities. Remarkably, the fossil flora had the lowest , which, together with low median P50 (−1.9 MPa), indicate that the Olmos paleoforest species were extremely vulnerable to drought-induced cavitation. Our findings support paleoclimate inferences from leaf physiognomy and paleoclimatic models suggesting it represented a highly productive wet tropical rainforest. Our results also indicate that the Olmos Formation plants had a large range of water conduction strategies, but more restricted variation in cavitation resistance. These straightforward methods for measuring hydraulic properties, used herein for the first time, can provide useful information on the ecological strategies of paleofloras and on temporal shifts in ecological function of fossil forests chronosequences.
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122
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Jacobsen AL, Pratt RB, Davis SD, Tobin MF. Geographic And Seasonal Variation In Chaparral Vulnerability To Cavitation. ACTA ACUST UNITED AC 2014. [DOI: 10.3120/0024-9637-61.4.317] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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123
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Madrid EN, Armitage AR, López-Portillo J. Avicennia germinans (black mangrove) vessel architecture is linked to chilling and salinity tolerance in the Gulf of Mexico. FRONTIERS IN PLANT SCIENCE 2014; 5:503. [PMID: 25309570 PMCID: PMC4176030 DOI: 10.3389/fpls.2014.00503] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 09/09/2014] [Indexed: 06/04/2023]
Abstract
Over the last several decades, the distribution of the black mangrove Avicennia germinans in the Gulf of Mexico has expanded, in part because it can survive the occasional freeze events and high soil salinities characteristic of the area. Vessel architecture may influence mangrove chilling and salinity tolerance. We surveyed populations of A. germinans throughout the Gulf to determine if vessel architecture was linked to field environmental conditions. We measured vessel density, hydraulically weighted vessel diameter, potential conductance capacity, and maximum tensile fracture stress. At each sampling site we recorded mangrove canopy height and soil salinity, and determined average minimum winter temperature from archived weather records. At a subset of sites, we measured carbon fixation rates using a LI-COR 6400XT Portable Photosynthesis System. Populations of A. germinans from cooler areas (Texas and Louisiana) had narrower vessels, likely reducing the risk of freeze-induced embolisms but also decreasing water conductance capacity. Vessels were also narrower in regions with high soil salinity, including Texas, USA and tidal flats in Veracruz, Mexico. Vessel density did not consistently vary with temperature or soil salinity. In abiotically stressful areas, A. germinans had a safe hydraulic architecture with narrower vessels that may increase local survival. This safe architecture appears to come at a substantial physiological cost in terms of reduction in conductance capacity and carbon fixation potential, likely contributing to lower canopy heights. The current distribution of A. germinans in the Gulf is influenced by the complex interplay between temperature, salinity, and vessel architecture. Given the plasticity of A. germinans vessel characters, it is likely that this mangrove species will be able to adapt to a wide range of potential future environmental conditions, and continue its expansion in the Gulf of Mexico in response to near-term climate change.
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Affiliation(s)
- Eric N. Madrid
- Department of Marine Biology, Texas A&M University at GalvestonGalveston, TX, USA
| | - Anna R. Armitage
- Department of Marine Biology, Texas A&M University at GalvestonGalveston, TX, USA
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Augusto L, Davies TJ, Delzon S, De Schrijver A. The enigma of the rise of angiosperms: can we untie the knot? Ecol Lett 2014; 17:1326-38. [PMID: 24975818 DOI: 10.1111/ele.12323] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/02/2014] [Accepted: 06/10/2014] [Indexed: 11/29/2022]
Abstract
Multiple hypotheses have been put forward to explain the rise of angiosperms to ecological dominance following the Cretaceous. A unified scheme incorporating all these theories appears to be an inextricable knot of relationships, processes and plant traits. Here, we revisit these hypotheses, categorising them within frameworks based on plant carbon economy, resistance to climatic stresses, nutrient economy, biotic interactions and diversification. We maintain that the enigma remains unresolved partly because our current state of knowledge is a result of the fragmentary nature of palaeodata. This lack of palaeodata limits our ability to draw firm conclusions. Nonetheless, based on consistent results, some inferences may be drawn. Our results indicate that a complex multidriver hypothesis may be more suitable than any single-driver theory. We contend that plant carbon economy and diversification may have played an important role during the early stages of gymnosperms replacement by angiosperms in fertile tropical sites. Plant tolerance to climatic stresses, plant nutrition, biotic interactions and diversification may have played a role in later stages of angiosperm expansion within temperate and harsh environments. The angiosperm knot remains partly tied, but to unravel it entirely will only be feasible if new discoveries are made by scientific communities.
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Affiliation(s)
- L Augusto
- INRA, Bordeaux Sciences Agro, UMR 1391 ISPA, Villenave d'Ornon, 33882, France
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125
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Poulos HM. Tree mortality from a short-duration freezing event and global-change-type drought in a Southwestern piñon-juniper woodland, USA. PeerJ 2014; 2:e404. [PMID: 24949231 PMCID: PMC4060029 DOI: 10.7717/peerj.404] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 05/07/2014] [Indexed: 11/20/2022] Open
Abstract
This study documents tree mortality in Big Bend National Park in Texas in response to the most acute one-year drought on record, which occurred following a five-day winter freeze. I estimated changes in forest stand structure and species composition due to freezing and drought in the Chisos Mountains of Big Bend National Park using permanent monitoring plot data. The drought killed over half (63%) of the sampled trees over the entire elevation gradient. Significant mortality occurred in trees up to 20 cm diameter (P < 0.05). Pinus cembroides Zucc. experienced the highest seedling and tree mortality (P < 0.0001) (55% of piñon pines died), and over five times as many standing dead pines were observed in 2012 than in 2009. Juniperus deppeana vonSteudal and Quercus emoryi Leibmann also experienced significant declines in tree density (P < 0.02) (30.9% and 20.7%, respectively). Subsequent droughts under climate change will likely cause even greater damage to trees that survived this record drought, especially if such events follow freezes. The results from this study highlight the vulnerability of trees in the Southwest to climatic change and that future shifts in forest structure can have large-scale community consequences.
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Affiliation(s)
- Helen M. Poulos
- College of the Environment, Wesleyan University, Middletown, CT, United States
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126
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Medeiros JS, Pockman WT. Freezing regime and trade-offs with water transport efficiency generate variation in xylem structure across diploid populations of Larrea sp. (Zygophyllaceae). AMERICAN JOURNAL OF BOTANY 2014; 101:598-607. [PMID: 24699537 DOI: 10.3732/ajb.1400046] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
PREMISE OF THE STUDY The impact of changing temperature regime on plant distributions may depend on the nature of physiological variation among populations. The arid-land genus Larrea spans habitats with a range of freezing frequency in North and South America. We hypothesized that variation in xylem anatomy among populations and species within this genus is driven by plasticity and trade-offs between safety from freeze-thaw embolism and water transport efficiency. METHODS We measured vessel density and diameter distributions to predict freeze-thaw embolism and water transport capacity for high and low latitude populations of three Larrea species grown in the field and a greenhouse common garden. KEY RESULTS Among field-grown L. divaricata, low latitude plants had larger mean vessel diameter and greater predicted freeze-thaw embolism, but higher water transport capacity compared with high latitude plants. Though high latitude L. tridentata and L. nitida had abundant smaller vessels, these plants also produced very large vessels and had semi ring-porous wood structure. Thus, their predicted embolism and water transport capacity were comparable to those of low latitude plants. Differences among field-grown and common-garden-grown plants demonstrate that plasticity contributes to population differentiation in xylem characters, though high latitude L. divaricata exhibited relatively lower plasticity. CONCLUSIONS Our results indicate that a trade-off between transport safety and efficiency contributes substantially to variation in xylem structure within the genus Larrea. In addition, we suggest that xylem plasticity may play a role in negotiating these trade-offs, with implications for responses to future climate change.
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127
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Rockwell FE, Wheeler JK, Holbrook NM. Cavitation and its discontents: opportunities for resolving current controversies. PLANT PHYSIOLOGY 2014; 164:1649-60. [PMID: 24501002 PMCID: PMC3982731 DOI: 10.1104/pp.113.233817] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 02/02/2014] [Indexed: 05/18/2023]
Abstract
Cavitation has long been recognized as a key constraint on the structure and functional integrity of the xylem. Yet, recent results call into question how well we understand cavitation in plants. Here, we consider embolism formation in angiosperms at two scales. The first focuses on how air-seeding occurs at the level of pit membranes, raising the question of whether capillary failure is an appropriate physical model. The second addresses methodological uncertainties that affect our ability to infer the formation of embolism and its reversal in plant stems. Overall, our goal is to open up fresh perspectives on the structure-function relationships of xylem.
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Affiliation(s)
- Fulton E. Rockwell
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853 (F.E.R.); and
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138 (J.K.W., N.M.H.)
| | - James K. Wheeler
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853 (F.E.R.); and
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138 (J.K.W., N.M.H.)
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128
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Zanne AE, Tank DC, Cornwell WK, Eastman JM, Smith SA, FitzJohn RG, McGlinn DJ, O’Meara BC, Moles AT, Reich PB, Royer DL, Soltis DE, Stevens PF, Westoby M, Wright IJ, Aarssen L, Bertin RI, Calaminus A, Govaerts R, Hemmings F, Leishman MR, Oleksyn J, Soltis PS, Swenson NG, Warman L, Beaulieu JM. Three keys to the radiation of angiosperms into freezing environments. Nature 2013; 506:89-92. [DOI: 10.1038/nature12872] [Citation(s) in RCA: 1010] [Impact Index Per Article: 91.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Accepted: 11/05/2013] [Indexed: 11/09/2022]
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Smith MS, Fridley JD, Yin J, Bauerle TL. Contrasting xylem vessel constraints on hydraulic conductivity between native and non-native woody understory species. FRONTIERS IN PLANT SCIENCE 2013; 4:486. [PMID: 24348490 PMCID: PMC3842846 DOI: 10.3389/fpls.2013.00486] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 11/11/2013] [Indexed: 05/03/2023]
Abstract
We examined the hydraulic properties of 82 native and non-native woody species common to forests of Eastern North America, including several congeneric groups, representing a range of anatomical wood types. We observed smaller conduit diameters with greater frequency in non-native species, corresponding to lower calculated potential vulnerability to cavitation index. Non-native species exhibited higher vessel-grouping in metaxylem compared with native species, however, solitary vessels were more prevalent in secondary xylem. Higher frequency of solitary vessels in secondary xylem was related to a lower potential vulnerability index. We found no relationship between anatomical characteristics of xylem, origin of species and hydraulic conductivity, indicating that non-native species did not exhibit advantageous hydraulic efficiency over native species. Our results confer anatomical advantages for non-native species under the potential for cavitation due to freezing, perhaps permitting extended growing seasons.
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Affiliation(s)
- Maria S. Smith
- Department of Horticulture, Cornell UniversityIthaca, NY, USA
| | | | - Jingjing Yin
- Department of Horticulture, Cornell UniversityIthaca, NY, USA
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130
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Affiliation(s)
- Roberto Tognetti
- Dipartimento di Bioscienze e Territorio, Università degli Studi del Molise, 86090 Pesche, Italy
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131
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Charrier G, Cochard H, Améglio T. Evaluation of the impact of frost resistances on potential altitudinal limit of trees. TREE PHYSIOLOGY 2013; 33:891-902. [PMID: 24052567 DOI: 10.1093/treephys/tpt062] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Winter physiology of woody plants is a key issue in temperate biomes. Here, we investigated different frost resistance mechanisms on 1-year-old branches of 11 European tree species from November until budburst: (i) frost hardiness of living cells (by electrolyte leakage method), (ii) winter embolism sensitivity (by percentage loss of conductivity: PLC) and (iii) phenological variation of budburst (by thermal time to budburst). These ecophysiological traits were analyzed according to the potential altitudinal limit, which is highly related to frost exposure. Seasonal frost hardiness and PLC changes are relatively different across species. Maximal PLC observed in winter (PLCMax) was the factor most closely related to potential altitudinal limit. Moreover, PLCMax was related to the mean hydraulic diameter of vessels (indicating embolism sensitivity) and to osmotic compounds (indicating ability of living cells to refill xylem conducting elements). Winter embolism formation seems to be counterbalanced by active refilling from living cells. These results enabled us to model potential altitudinal limit according to three of the physiological/anatomical parameters studied. Monitoring different frost resistance strategies brings new insights to our understanding of the altitudinal limits of trees.
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132
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Beikircher B, Mayr S. Winter peridermal conductance of apple trees: lammas shoots and spring shoots compared. TREES (BERLIN, GERMANY : WEST) 2013; 27:707-715. [PMID: 23794789 PMCID: PMC3688303 DOI: 10.1007/s00468-012-0826-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 11/29/2012] [Accepted: 12/03/2012] [Indexed: 05/10/2023]
Abstract
Lammas shoots are flushes formed by some woody species later in the growing season. Having less time to develop, tissue formation is suggested to be incomplete leading to a higher peridermal water loss during consecutive months. In this study, we analysed morphological and anatomical parameters, peridermal conductance to water vapour and the level of native embolism in mid-winter and late-winter of lammas shoots and normal spring shoots of the apple varieties Malus domestica 'Gala' and 'Nicoter'. Lammas shoots showed a significantly higher shoot cross-sectional area due to larger pith and corticular parenchyma areas. In contrast, phloem was significantly thicker in spring shoots. No pronounced differences were observed in xylem and collenchyma thickness or mean hydraulic conduit diameter. The phellem of spring shoots was composed of more suberinised cells compared to lammas shoots, which led to a significantly higher peridermal conductance in the latter. The amount of native embolism in mid-winter did not differ between shoot types, but in late-winter lammas shoots were more embolised than spring shoots. Data show that the restricted vegetation period of lammas shoots affects their development and, in consequence, their transpiration shield. This may also pose a risk for winter desiccation.
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Affiliation(s)
- B. Beikircher
- Institute of Botany, University of Innsbruck, Sternwartestraße 15, 6020 Innsbruck, Austria
| | - S. Mayr
- Institute of Botany, University of Innsbruck, Sternwartestraße 15, 6020 Innsbruck, Austria
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133
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Lens F, Tixier A, Cochard H, Sperry JS, Jansen S, Herbette S. Embolism resistance as a key mechanism to understand adaptive plant strategies. CURRENT OPINION IN PLANT BIOLOGY 2013; 16:287-92. [PMID: 23453076 DOI: 10.1016/j.pbi.2013.02.005] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 02/07/2013] [Indexed: 05/21/2023]
Abstract
One adaptation of plants to cope with drought or frost stress is to develop wood that is able to withstand the formation and distribution of air bubbles (emboli) in its water conducting xylem cells under negative pressure. The ultrastructure of interconduit pits strongly affects drought-induced embolism resistance, but also mechanical properties of the xylem are involved. The first experimental evidence for a lower embolism resistance in stems of herbaceous plants compared to stems of their secondarily woody descendants further supports this mechanical-functional trade-off. An integrative approach combining (ultra)structural observations of the xylem, safety-efficiency aspects of the hydraulic pipeline, and xylem-phloem interactions will shed more light on the multiple adaptive strategies of embolism resistance in plants.
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Affiliation(s)
- Frederic Lens
- Naturalis Biodiversity Center, Leiden University, P.O. Box 9514, NL-2300 RA Leiden, The Netherlands.
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134
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Christensen-Dalsgaard KK, Tyree MT. Does freezing and dynamic flexing of frozen branches impact the cavitation resistance of Malus domestica and the Populus clone Walker? Oecologia 2013; 173:665-74. [DOI: 10.1007/s00442-013-2656-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 04/05/2013] [Indexed: 11/28/2022]
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135
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Brodersen CR, McElrone AJ. Maintenance of xylem Network Transport Capacity: A Review of Embolism Repair in Vascular Plants. FRONTIERS IN PLANT SCIENCE 2013; 4:108. [PMID: 23630539 PMCID: PMC3633935 DOI: 10.3389/fpls.2013.00108] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 04/09/2013] [Indexed: 05/17/2023]
Abstract
Maintenance of long distance water transport in xylem is essential to plant health and productivity. Both biotic and abiotic environmental conditions lead to embolism formation within the xylem resulting in lost transport capacity and ultimately death. Plants exhibit a variety of strategies to either prevent or restore hydraulic capacity through cavitation resistance with specialized anatomy, replacement of compromised conduits with new growth, and a metabolically active embolism repair mechanism. In recent years, mounting evidence suggests that metabolically active cells surrounding the xylem conduits in some, but not all, species are capable of restoring hydraulic conductivity. This review summarizes our current understanding of the osmotically driven embolism repair mechanism, the known genetic and anatomical components related to embolism repair, rehydration pathways through the xylem, and the role of capacitance. Anatomical differences between functional plant groups may be one of the limiting factors that allow some plants to refill while others do not, but further investigations are necessary to fully understand this dynamic process. Finally, xylem networks should no longer be considered an assemblage of dead, empty conduits, but instead a metabolically active tissue finely tuned to respond to ever changing environmental cues.
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Affiliation(s)
- Craig R. Brodersen
- Horticultural Sciences Department, Citrus Research and Education Center, University of FloridaLake Alfred, FL, USA
| | - Andrew J. McElrone
- Crops Pathology and Genetics Research Unit, USDA-ARSDavis, CA, USA
- Department of Viticulture and Enology, University of California DavisDavis, CA, USA
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136
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Lucas WJ, Groover A, Lichtenberger R, Furuta K, Yadav SR, Helariutta Y, He XQ, Fukuda H, Kang J, Brady SM, Patrick JW, Sperry J, Yoshida A, López-Millán AF, Grusak MA, Kachroo P. The plant vascular system: evolution, development and functions. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2013; 55:294-388. [PMID: 23462277 DOI: 10.1111/jipb.12041] [Citation(s) in RCA: 398] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The emergence of the tracheophyte-based vascular system of land plants had major impacts on the evolution of terrestrial biology, in general, through its role in facilitating the development of plants with increased stature, photosynthetic output, and ability to colonize a greatly expanded range of environmental habitats. Recently, considerable progress has been made in terms of our understanding of the developmental and physiological programs involved in the formation and function of the plant vascular system. In this review, we first examine the evolutionary events that gave rise to the tracheophytes, followed by analysis of the genetic and hormonal networks that cooperate to orchestrate vascular development in the gymnosperms and angiosperms. The two essential functions performed by the vascular system, namely the delivery of resources (water, essential mineral nutrients, sugars and amino acids) to the various plant organs and provision of mechanical support are next discussed. Here, we focus on critical questions relating to structural and physiological properties controlling the delivery of material through the xylem and phloem. Recent discoveries into the role of the vascular system as an effective long-distance communication system are next assessed in terms of the coordination of developmental, physiological and defense-related processes, at the whole-plant level. A concerted effort has been made to integrate all these new findings into a comprehensive picture of the state-of-the-art in the area of plant vascular biology. Finally, areas important for future research are highlighted in terms of their likely contribution both to basic knowledge and applications to primary industry.
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Affiliation(s)
- William J Lucas
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA.
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137
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Ogasa M, Miki NH, Murakami Y, Yoshikawa K. Recovery performance in xylem hydraulic conductivity is correlated with cavitation resistance for temperate deciduous tree species. TREE PHYSIOLOGY 2013; 33:335-44. [PMID: 23492871 DOI: 10.1093/treephys/tpt010] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Woody species hydraulically vulnerable to xylem cavitation may experience daily xylem embolism. How such species cope with the possibility of accumulated embolism is unclear. In this study, we examined seven temperate woody species to assess the hypothesis that low cavitation resistance (high vulnerability to cavitation) is compensated by high recovery performance via vessel refilling. We also evaluated leaf functional and xylem structural traits. The xylem recovery index (XRI), defined as the ratio of xylem hydraulic conductivity in plants rewatered after soil drought to that in plants under moist conditions, varied among species. The xylem water potential causing 50% loss of hydraulic conductivity (Ψ50) varied among the species studied, whereas only a slight difference was detected with respect to midday xylem water potential (Ψmin), indicating smaller hydraulic safety margins (Ψmin - Ψ50) for species more vulnerable to cavitation. Cavitation resistance (|Ψ50|) was negatively correlated with XRI across species, with cavitation-vulnerable species showing a higher performance in xylem recovery. Wood density was positively correlated with cavitation resistance and was negatively correlated with XRI. These novel results reveal that coordination exists between cavitation resistance and xylem recovery performance, in association with wood functional traits such as denser wood for cavitation-resistant xylem and less-dense but water-storable wood for refillable xylem. These findings provide insights into long-term maintenance of water transport in tree species growing under variable environmental conditions.
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Affiliation(s)
- Mayumi Ogasa
- Graduate School of Environmental Science, Okayama University, Okayama 700-8530, Japan.
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138
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Brodersen CR, McElrone AJ, Choat B, Lee EF, Shackel KA, Matthews MA. In vivo visualizations of drought-induced embolism spread in Vitis vinifera. PLANT PHYSIOLOGY 2013; 161:1820-9. [PMID: 23463781 PMCID: PMC3613458 DOI: 10.1104/pp.112.212712] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 03/04/2013] [Indexed: 05/02/2023]
Abstract
Long-distance water transport through plant xylem is vulnerable to hydraulic dysfunction during periods of increased tension on the xylem sap, often coinciding with drought. While the effects of local and systemic embolism on plant water transport and physiology are well documented, the spatial patterns of embolism formation and spread are not well understood. Using a recently developed nondestructive diagnostic imaging tool, high-resolution x-ray computed tomography, we documented the dynamics of drought-induced embolism in grapevine (Vitis vinifera) plants in vivo, producing the first three-dimensional, high-resolution, time-lapse observations of embolism spread. Embolisms formed first in the vessels surrounding the pith at stem water potentials of approximately -1.2 megapascals in drought experiments. As stem water potential decreased, embolisms spread radially toward the epidermis within sectored vessel groupings via intervessel connections and conductive xylem relays, and infrequently (16 of 629 total connections) through lateral connections into adjacent vessel sectors. Theoretical loss of conductivity calculated from the high-resolution x-ray computed tomography images showed good agreement with previously published nuclear magnetic resonance imaging and hydraulic conductivity experiments also using grapevine. Overall, these data support a growing body of evidence that xylem organization is critically important to the isolation of drought-induced embolism spread and confirm that air seeding through the pit membranes is the principle mechanism of embolism spread.
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Affiliation(s)
- Craig Robert Brodersen
- Horticultural Sciences Department-Citrus Research and Education Center, University of Florida, Lake Alfred, Florida 33850, USA.
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139
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Gremer JR, Kimball S, Angert AL, Venable DL, Huxman TE. Variation in photosynthetic response to temperature in a guild of winter annual plants. Ecology 2013; 93:2693-704. [PMID: 23431599 DOI: 10.1890/12-0006.1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
How species respond to environmental variation can have important consequences for population and community dynamics. Temperature, in particular, is one source of variation expected to strongly influence plant performance. Here, we compared photosynthetic responses to temperature across a guild of winter annual plants. Previous work in this system identified a trade-off between relative growth rate (RGR) and water-use efficiency (WUE) that predicts species differences in population dynamics over time, which then contribute to long-term species coexistence. Interestingly, species with high WUE invest in photosynthetic processes that appear to maximize carbon assimilation, while high-RGR species appear to maximize carbon gain by increasing leaf area for photosynthesis. In high-WUE species, higher rates of carbon acquisition were associated with increased investment into light-driven electron transport (J(max)). We tested whether such allocation allows these plants to have greater photosynthetic performance at lower temperatures by comparing the temperature sensitivity of photosynthesis across species in the community. Six species were grown in buried pots in the field, allowing them to experience natural changes in seasonal temperature. Plants were taken from the field and placed in growth chambers where photosynthetic performance was measured following short-term exposure to a wide range of temperatures. These measurements were repeated throughout the season. Our results suggest that high-WUE species are more efficient at processing incoming light, as measured by chlorophyll fluorescence, and exhibit higher net photosynthetic rates (A(net)) than high-RGR species, and these advantages are greatest at low temperatures. Sampling date differentially affected fluorescence across species, while species had similar seasonal changes in A(net). Our results suggest that species-specific responses to temperature contribute to the WUE-RGR trade-off that has been shown to promote coexistence in this community. These differential responses to environmental conditions can have important effects on fitness, population dynamics, and community structure.
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Affiliation(s)
- Jennifer R Gremer
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA.
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140
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Lusk CH, Kelly JWG, Gleason SM. Light requirements of Australian tropical vs. cool-temperate rainforest tree species show different relationships with seedling growth and functional traits. ANNALS OF BOTANY 2013; 111:479-488. [PMID: 23264237 PMCID: PMC3579444 DOI: 10.1093/aob/mcs289] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Accepted: 11/15/2012] [Indexed: 06/01/2023]
Abstract
BACKGROUND AND AIMS A trade-off between shade tolerance and growth in high light is thought to underlie the temporal dynamics of humid forests. On the other hand, it has been suggested that tree species sorting on temperature gradients involves a trade-off between growth rate and cold resistance. Little is known about how these two major trade-offs interact. METHODS Seedlings of Australian tropical and cool-temperate rainforest trees were grown in glasshouse environments to compare growth versus shade-tolerance trade-offs in these two assemblages. Biomass distribution, photosynthetic capacity and vessel diameters were measured in order to examine the functional correlates of species differences in light requirements and growth rate. Species light requirements were assessed by field estimation of the light compensation point for stem growth. RESULTS Light-demanding and shade-tolerant tropical species differed markedly in relative growth rates (RGR), but this trend was less evident among temperate species. This pattern was paralleled by biomass distribution data: specific leaf area (SLA) and leaf area ratio (LAR) of tropical species were significantly positively correlated with compensation points, but not those of cool-temperate species. The relatively slow growth and small SLA and LAR of Tasmanian light-demanders were associated with narrow vessels and low potential sapwood conductivity. CONCLUSIONS The conservative xylem traits, small LAR and modest RGR of Tasmanian light-demanders are consistent with selection for resistance to freeze-thaw embolism, at the expense of growth rate. Whereas competition for light favours rapid growth in light-demanding trees native to environments with warm, frost-free growing seasons, frost resistance may be an equally important determinant of the fitness of light-demanders in cool-temperate rainforest, as seedlings establishing in large openings are exposed to sub-zero temperatures that can occur throughout most of the year.
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Affiliation(s)
- Christopher H Lusk
- Department of Biological Sciences, University of Waikato, Private Bag 3105, Hamilton, New Zealand.
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141
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Jiménez‐Castillo M, Lusk CH. Vascular performance of woody plants in a temperate rain forest: lianas suffer higher levels of freeze–thaw embolism than associated trees. Funct Ecol 2013. [DOI: 10.1111/1365-2435.12045] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Mylthon Jiménez‐Castillo
- Instituto de Ciencias Ambientales y Evolutivas, Universidad Austral de Chile Casilla 567 Valdivia Chile
- Jardín Botánico Universidad Austral de Chile Valdivia Chile
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142
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Schreiber SG, Hamann A, Hacke UG, Thomas BR. Sixteen years of winter stress: an assessment of cold hardiness, growth performance and survival of hybrid poplar clones at a boreal planting site. PLANT, CELL & ENVIRONMENT 2013; 36:419-28. [PMID: 22897210 DOI: 10.1111/j.1365-3040.2012.02583.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
In recent years, thousands of hectares of hybrid poplar plantations have been established in Canada for the purpose of carbon sequestration and wood production. However, boreal planting environments pose special challenges that may compromise the long-term survival and productivity of such plantations. In this study, we evaluated the effect of winter stress, that is, frequent freeze-thaw and extreme cold events, on growth and survival of 47 hybrid poplar clones in a long-term field experiment. We further assessed physiological and structural traits that are potentially important for cold tolerance for a selected set of seven clones. We found that trees with narrow xylem vessels showed reduced freezing-induced embolism and showed superior productivity after 16 growing seasons. With respect to cold hardiness of living tissues, we only observed small differences among clones in early autumn, which were nonetheless significantly correlated to growth. Maximum winter cold hardiness and the timing of leaf senescence and budbreak were not related to growth or survival. In conclusion, our data suggest that reduction of freezing-induced embolism due to small vessel diameters is an essential adaptive trait to ensure long-term productivity of hybrid poplar plantations in boreal planting environments.
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Affiliation(s)
- Stefan G Schreiber
- Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada T6G 2H1.
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143
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Schüller E, Martínez-Ramos M, Hietz P. Radial Gradients in Wood Specific Gravity, Water and Gas Content in Trees of a Mexican Tropical Rain Forest. Biotropica 2013. [DOI: 10.1111/btp.12016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Elisabeth Schüller
- Institute of Botany; Department of Integrative Biology; University of Natural Resources and Life Sciences (Boku); Gregor-Mendel-Str. 33; 1180 Vienna; Austria
| | - Miguel Martínez-Ramos
- Centro de Investigaciones en Ecosistemas; Universidad Nacional Autónoma de México; AP 27-3 Santa María de Guido; CP 58089; Morelia; Michoacán; Mexico
| | - Peter Hietz
- Institute of Botany; Department of Integrative Biology; University of Natural Resources and Life Sciences (Boku); Gregor-Mendel-Str. 33; 1180 Vienna; Austria
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144
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Sevanto S, Holbrook NM, Ball MC. Freeze/Thaw-induced embolism: probability of critical bubble formation depends on speed of ice formation. FRONTIERS IN PLANT SCIENCE 2012; 3:107. [PMID: 22685446 PMCID: PMC3368182 DOI: 10.3389/fpls.2012.00107] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 05/07/2012] [Indexed: 05/18/2023]
Abstract
Bubble formation in the conduits of woody plants sets a challenge for uninterrupted water transportation from the soil up to the canopy. Freezing and thawing of stems has been shown to increase the number of air-filled (embolized) conduits, especially in trees with large conduit diameters. Despite numerous experimental studies, the mechanisms leading to bubble formation during freezing have not been addressed theoretically. We used classical nucleation theory and fluid mechanics to show which mechanisms are most likely to be responsible for bubble formation during freezing and what parameters determine the likelihood of the process. Our results confirm the common assumption that bubble formation during freezing is most likely due to gas segregation by ice. If xylem conduit walls are not permeable to the salts expelled by ice during the freezing process, osmotic pressures high enough for air seeding could be created. The build-up rate of segregated solutes in front of the ice-water interface depends equally on conduit diameter and freezing velocity. Therefore, bubble formation probability depends on these variables. The dependence of bubble formation probability on freezing velocity means that the experimental results obtained for cavitation threshold conduit diameters during freeze/thaw cycles depend on the experimental setup; namely sample size and cooling rate. The velocity dependence also suggests that to avoid bubble formation during freezing trees should have narrow conduits where freezing is likely to be fast (e.g., branches or outermost layer of the xylem). Avoidance of bubble formation during freezing could thus be one piece of the explanation why xylem conduit size of temperate and boreal zone trees varies quite systematically.
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Affiliation(s)
- Sanna Sevanto
- Department of Organismic and Evolutionary Biology, Harvard University Cambridge, MA, USA
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145
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Voelker SL, Noirot-Cosson PE, Stambaugh MC, McMurry ER, Meinzer FC, Lachenbruch B, Guyette RP. Spring temperature responses of oaks are synchronous with North Atlantic conditions during the last deglaciation. ECOL MONOGR 2012. [DOI: 10.1890/11-0848.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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146
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Medeiros JS, Marshall DL, Maherali H, Pockman WT. Variation in seedling freezing response is associated with climate in Larrea. Oecologia 2012; 169:73-84. [PMID: 22068319 PMCID: PMC3711214 DOI: 10.1007/s00442-011-2181-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 10/20/2011] [Indexed: 11/30/2022]
Abstract
Variation in freezing severity is hypothesized to have influenced the distribution and evolution of the warm desert evergreen genus Larrea. If this hypothesis is correct, performance and survival of species and populations should vary predictably along gradients of freezing severity. If freezing environment changes in the future, the ability of Larrea to adapt will depend on the structure of variation for freezing resistance within populations. To test whether freezing responses vary among and within Larrea populations, we grew maternal families of seedlings from high and low latitude L. divaricata and high latitude L. tridentata populations in a common garden. We measured survival, projected plant area and dark-adapted chlorophyll fluorescence (F (v) /F (m)) before and after cold acclimation and for 2 weeks following a single freeze. We detected significant variation in freezing resistance among species and populations. Maternal family lines differed significantly in their responses to cold acclimation and/or freezing for two out of the three populations: among L. tridentata maternal families and among low latitude L. divaricata maternal families. There were no significant differences across maternal families of high latitude L. divaricata. Our results indicate that increased freezing resistance in high latitude populations likely facilitated historical population expansion of both species into colder climates, but this may have occurred to a greater extent for L. tridentata than for L. divaricata. Differences in the structure of variation for cold acclimation and freezing responses among populations suggest potential differences in their ability to evolve in response to future changes in freezing severity.
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Affiliation(s)
- Juliana S Medeiros
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA.
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147
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Hölttä T, Mencuccini M, Nikinmaa E. A carbon cost-gain model explains the observed patterns of xylem safety and efficiency. PLANT, CELL & ENVIRONMENT 2011; 34:1819-34. [PMID: 21689111 DOI: 10.1111/j.1365-3040.2011.02377.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Efficient water transport from the soil to the leaves is essential for plant function, while building and maintaining the water transport structure in the xylem require a major proportion of the assimilated carbon of the tree. Xylem transport also faces additional challenges as water in the xylem is under tension and therefore cavitation cannot be completely avoided. We constructed a model that calculates the xylem structure that maximizes carbon-use efficiency while simultaneously taking into account pit structure in increasing the resistance to water transport and constricting the spreading of embolisms. The optimal xylem structure predicted by the model was found to correspond well to the generally observed trends: xylem conduits grew in size from the apex towards the base while simultaneously decreasing in number, and vulnerability to cavitation increased with conduit size. These trends were caused primarily by the axial water potential gradient in the xylem. The pits have to be less porous near the apex where water potential is lower to restrict the spreading of embolisms, while whole-plant carbon-use efficiency demands that conduit size decreases and conduit number increases simultaneously. The model predictions remained qualitatively the same regardless of the exact optimality criterion used for defining carbon-use efficiency.
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Affiliation(s)
- Teemu Hölttä
- Department of Forest Sciences, 00014 University of Helsinki, Helsinki, Finland.
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148
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Creese C, Benscoter AM, Maherali H. Xylem function and climate adaptation in Pinus. AMERICAN JOURNAL OF BOTANY 2011; 98:1437-1445. [PMID: 21865504 DOI: 10.3732/ajb.1100123] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
PREMISE OF THE STUDY The distribution of species is determined in part by their functional traits. One important function is the ability of xylem to supply water to leaves and withstand water-stress-induced cavitation. These hydraulic traits are hypothesized to have evolved in response to selection by precipitation and temperature. • METHODS We grew 26 species in the genus Pinus in a common environment and used phylogenetic comparative methods to examine whether the evolution of seedling hydraulic and wood density traits were associated with the climate of the extant geographic range of the species. We also examined whether these traits were correlated with each other, with integrated water-use efficiency (WUE), and with plant growth. • KEY RESULTS Contrary to predictions from a hydraulic model, we found no association between stem hydraulic conductivity (K(S)) and precipitation, even though there was substantial variation for K(S) in the genus. Nevertheless, K(S) was positively correlated with temperature, plant biomass, and WUE. Wood density was infrequently associated with climate or correlated with other traits except for plant biomass. • CONCLUSIONS Reduced K(S) in cold climates, if associated with reduced conduit diameter, likely evolved to increase resistance to freezing-induced xylem cavitation. The absence of a K(S)-precipitation relationship among Pinus seedlings suggests that associations between hydraulic traits and precipitation found in adult trees arise through plastic responses to moisture availability and/or develop over ontogeny. The weak association among wood density, climate, and other traits suggest that this trait does not contribute to climate adaptation in Pinus.
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Affiliation(s)
- Chris Creese
- Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Choat B, Medek DE, Stuart SA, Pasquet-Kok J, Egerton JJG, Salari H, Sack L, Ball MC. Xylem traits mediate a trade-off between resistance to freeze-thaw-induced embolism and photosynthetic capacity in overwintering evergreens. THE NEW PHYTOLOGIST 2011; 191:996-1005. [PMID: 21627664 DOI: 10.1111/j.1469-8137.2011.03772.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Hydraulic traits were studied in temperate, woody evergreens in a high-elevation heath community to test for trade-offs between the delivery of water to canopies at rates sufficient to sustain photosynthesis and protection against disruption to vascular transport caused by freeze-thaw-induced embolism. Freeze-thaw-induced loss in hydraulic conductivity was studied in relation to xylem anatomy, leaf- and sapwood-specific hydraulic conductivity and gas exchange characteristics of leaves. We found evidence that a trade-off between xylem transport capacity and safety from freeze-thaw-induced embolism affects photosynthetic activity in overwintering evergreens. The mean hydraulically weighted xylem vessel diameter and sapwood-specific conductivity correlated with susceptibility to freeze-thaw-induced embolism. There was also a strong correlation of hydraulic supply and demand across species; interspecific differences in stomatal conductance and CO(2) assimilation rates were correlated linearly with sapwood- and leaf-specific hydraulic conductivity. Xylem vessel anatomy mediated an apparent trade-off between resistance to freeze-thaw-induced embolism and hydraulic and photosynthetic capacity during the winter. These results point to a new role for xylem functional traits in determining the degree to which species can maintain photosynthetic carbon gain despite freezing events and cold winter temperatures.
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Affiliation(s)
- Brendan Choat
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Danielle E Medek
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Stephanie A Stuart
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Jessica Pasquet-Kok
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA 90095-1606, USA
| | - John J G Egerton
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Hooman Salari
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA 90095-1606, USA
| | - Marilyn C Ball
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
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