1
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Mekarni L, Cochard H, Lehmann MM, Turberg P, Grossiord C. In vivo X-ray microtomography locally affects stem radial growth with no immediate physiological impact. PLANT PHYSIOLOGY 2024; 196:153-163. [PMID: 38757896 DOI: 10.1093/plphys/kiae285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 04/17/2024] [Accepted: 04/17/2024] [Indexed: 05/18/2024]
Abstract
Microcomputed tomography (µCT) is a nondestructive X-ray imaging method used in plant physiology to visualize in situ plant tissues that enables assessments of embolized xylem vessels. Whereas evidence for X-ray-induced cellular damage has been reported, the impact on plant physiological processes such as carbon (C) uptake, transport, and use is unknown. Yet, these damages could be particularly relevant for studies that track embolism and C fluxes over time. We examined the physiological consequences of µCT scanning for xylem embolism over 3 mo by monitoring net photosynthesis (Anet), diameter growth, chlorophyll (Chl) concentration, and foliar nonstructural carbohydrate (NSC) content in 4 deciduous tree species: hedge maple (Acer campestre), ash (Fraxinus excelsior), European hornbeam (Carpinus betulus), and sessile oak (Quercus petraea). C transport from the canopy to the roots was also assessed through 13C labeling. Our results show that monthly X-ray application did not impact foliar Anet, Chl, NSC content, and C transport. Although X-ray effects did not vary between species, the most pronounced impact was observed in sessile oak, marked by stopped growth and stem deformations around the irradiated area. The absence of adverse impacts on plant physiology for all the tested treatments indicates that laboratory-based µCT systems can be used with different beam energy levels and doses without threatening the integrity of plant physiology within the range of tested parameters. However, the impacts of repetitive µCT on the stem radial growth at the irradiated zone leading to deformations in sessile oak might have lasting implications for studies tracking plant embolism in the longer-term.
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Affiliation(s)
- Laura Mekarni
- Plant Ecology Research Laboratory PERL, School of Architecture, Civil and Environmental Engineering, EPFL, CH-1015 Lausanne, Switzerland
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Community Ecology Unit, 8903 Birmensdorf, Switzerland
| | - Hervé Cochard
- Université Clermont Auvergne, INRAE, PIAF, 63000 Clermont-Ferrand, France
| | - Marco M Lehmann
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Community Ecology Unit, 8903 Birmensdorf, Switzerland
| | - Pascal Turberg
- Plant Ecology Research Laboratory PERL, School of Architecture, Civil and Environmental Engineering, EPFL, CH-1015 Lausanne, Switzerland
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Community Ecology Unit, 8903 Birmensdorf, Switzerland
| | - Charlotte Grossiord
- Plant Ecology Research Laboratory PERL, School of Architecture, Civil and Environmental Engineering, EPFL, CH-1015 Lausanne, Switzerland
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Community Ecology Unit, 8903 Birmensdorf, Switzerland
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2
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Martius LR, Mencuccini M, Bittencourt PRL, Moraes Alves M, Binks O, Sanchez-Martinez P, da Costa ACL, Meir P. Towards accurate monitoring of water content in woody tissue across tropical forests and other biomes. TREE PHYSIOLOGY 2024; 44:tpae076. [PMID: 38952005 PMCID: PMC11299548 DOI: 10.1093/treephys/tpae076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 06/05/2024] [Accepted: 06/26/2024] [Indexed: 07/03/2024]
Abstract
Forest ecosystems face increasing drought exposure due to climate change, necessitating accurate measurements of vegetation water content to assess drought stress and tree mortality risks. Although Frequency Domain Reflectometry offers a viable method for monitoring stem water content by measuring dielectric permittivity, challenges arise from uncertainties in sensor calibration linked to wood properties and species variability, impeding its wider usage. We sampled tropical forest trees and palms in eastern Amazônia to evaluate how sensor output differences are controlled by wood density, temperature and taxonomic identity. Three individuals per species were felled and cut into segments within a diverse dataset comprising five dicotyledonous tree and three monocotyledonous palm species on a wide range of wood densities. Water content was estimated gravimetrically for each segment using a temporally explicit wet-up/dry-down approach and the relationship with the dielectric permittivity was examined. Woody tissue density had no significant impact on the calibration, but species identity and temperature significantly affected sensor readings. The temperature artefact was quantitatively important at large temperature differences, which may have led to significant bias of daily and seasonal water content dynamics in previous studies. We established the first tropical tree and palm calibration equation which performed well for estimating water content. Notably, we demonstrated that the sensitivity remained consistent across species, enabling the creation of a simplified one-slope calibration for accurate, species-independent measurements of relative water content. Our one-slope calibration serves as a general, species-independent standard calibration for assessing relative water content in woody tissue, offering a valuable tool for quantifying drought responses and stress in trees and forest ecosystems.
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Affiliation(s)
- Lion R Martius
- School of GeoSciences, University of Edinburgh, King's Buildings, Alexander Crum Brown Rd, Edinburgh EH9 3FF, United Kingdom
| | - Maurizio Mencuccini
- CREAF, Campus UAB, Cerdanyola del Vallés 08193, Spain
- ICREA, Barcelona 08193, Spain
| | - Paulo R L Bittencourt
- Geography, College of Life and Environmental Sciences, University of Exeter, Amory Building, Exeter EX4 4RJ, United Kingdom
| | - Moisés Moraes Alves
- Instituto de Geociências, Universidade Federal do Pará, Belém, PA 66075-110, Brazil
| | - Oliver Binks
- CREAF, Campus UAB, Cerdanyola del Vallés 08193, Spain
| | - Pablo Sanchez-Martinez
- School of GeoSciences, University of Edinburgh, King's Buildings, Alexander Crum Brown Rd, Edinburgh EH9 3FF, United Kingdom
| | - Antonio C L da Costa
- Instituto de Geociências, Universidade Federal do Pará, Belém, PA 66075-110, Brazil
- Museu Paraense Emílio Goeldi, Belém, PA 66040-170, Brazil
| | - Patrick Meir
- School of GeoSciences, University of Edinburgh, King's Buildings, Alexander Crum Brown Rd, Edinburgh EH9 3FF, United Kingdom
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3
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Andriantelomanana T, Améglio T, Delzon S, Cochard H, Herbette S. Unpacking the point of no return under drought in poplar: insight from stem diameter variation. THE NEW PHYTOLOGIST 2024; 242:466-478. [PMID: 38406847 DOI: 10.1111/nph.19615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 02/02/2024] [Indexed: 02/27/2024]
Abstract
A specific, robust threshold for drought-induced tree mortality is needed to improve the prediction of forest dieback. Here, we tested the relevance of continuous measurements of stem diameter variations for identifying such a threshold, their relationship with hydraulic and cellular damage mechanisms, and the influence of growth conditions on these relationships. Poplar saplings were grown under well-watered, water-limited, or light-limited conditions and then submitted to a drought followed by rewatering. Stem diameter was continuously measured to investigate two parameters: the percentage loss of diameter (PLD) and the percentage of diameter recovery (DR) following rewatering. Water potentials, stomatal conductance, embolism, and electrolyte leakage were also measured, and light microscopy allowed investigating cell collapse induced by drought. The water release observed through loss of diameter occurred throughout the drought, regardless of growth conditions. Poplars did not recover from drought when PLD reached a threshold and this differed according to growth conditions but remained linked to cell resistance to damage and collapse. Our findings shed new light on the mechanisms of drought-induced tree mortality and indicate that PLD could be a relevant indicator of drought-induced tree mortality, regardless of the growth conditions.
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Affiliation(s)
| | - Thierry Améglio
- Université Clermont Auvergne, INRAE, PIAF, Clermont-Ferrand, 63000, France
| | - Sylvain Delzon
- Université Bordeaux, INRAE, BIOGECO, Pessac, 33615, France
| | - Hervé Cochard
- Université Clermont Auvergne, INRAE, PIAF, Clermont-Ferrand, 63000, France
| | - Stephane Herbette
- Université Clermont Auvergne, INRAE, PIAF, Clermont-Ferrand, 63000, France
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4
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Beckett HAA, Bryant C, Neeman T, Mencuccini M, Ball MC. Plasticity in branch water relations and stem hydraulic vulnerability enhances hydraulic safety in mangroves growing along a salinity gradient. PLANT, CELL & ENVIRONMENT 2024; 47:854-870. [PMID: 37975319 DOI: 10.1111/pce.14764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/05/2023] [Accepted: 10/31/2023] [Indexed: 11/19/2023]
Abstract
Coping with water stress depends on maintaining cellular function and hydraulic conductance. Yet measurements of vulnerability to drought and salinity do not often focus on capacitance in branch organs that buffer hydraulic function during water stress. The relationships between branch water relations, stem hydraulic vulnerability and stem anatomy were investigated in two co-occurring mangroves Aegiceras corniculatum and Rhizophora stylosa growing at low and high salinity. The dynamics of branch water release acted to conserve water content in the stem at the expense of the foliage during extended drying. Hydraulic redistribution from the foliage to the stem increased stem relative water content by up to 21%. The water potentials at which 12% and 50% loss of stem hydraulic conductivity occurred decreased by ~1.7 MPa in both species between low and high salinity sites. These coordinated tissue adjustments increased hydraulic safety despite declining turgor safety margins at higher salinity sites. Our results highlight the complex interplay of plasticity in organ-level water relations with hydraulic vulnerability in the maintenance of stem hydraulic function in mangroves distributed along salinity gradients. These results emphasise the importance of combining water relations and hydraulic vulnerability parameters to understand vulnerability to water stress across the whole plant.
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Affiliation(s)
- Holly A A Beckett
- Plant Science Division, Research School of Biology, Australian National University, Canberra, Australia
| | - Callum Bryant
- Plant Science Division, Research School of Biology, Australian National University, Canberra, Australia
| | - Teresa Neeman
- Biological Data Science Institute, Australian National University, Canberra, Australia
| | - Maurizio Mencuccini
- Ecological and Forestry Applications Research Centre (CREAF), Barcelona, Bellaterra, Spain
| | - Marilyn C Ball
- Plant Science Division, Research School of Biology, Australian National University, Canberra, Australia
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5
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Jupa R, Pokorná K. Bark wounding triggers gradual embolism spreading in two diffuse-porous tree species. TREE PHYSIOLOGY 2024; 44:tpad132. [PMID: 37930242 PMCID: PMC10849750 DOI: 10.1093/treephys/tpad132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
Xylem transport is essential for the growth, development and survival of vascular plants. Bark wounding may increase the risk of xylem transport failure by tension-driven embolism. However, the consequences of bark wounding for xylem transport are poorly understood. Here, we examined the impacts of the bark wounding on embolism formation, leaf water potential and gas exchange in the terminal branches of two diffuse-porous tree species (Acer platanoides L. and Prunus avium L.). The effects of bark removal were examined on field-grown mature trees exposed to increased evaporative demands on a short-term and longer-term basis (6 h vs 6 days after bark wounding). Bark removal of 30% of branch circumference had a limited effect on the xylem hydraulic conductivity when embolized vessels were typically restricted to the last annual ring near the bark wound. Over the 6-day exposure, the non-conductive xylem area had significantly increased in the xylem tissue underneath the bark wound (from 22-29% to 51-52% of the last annual ring area in the bark wound zone), pointing to gradual yet relatively limited embolism spreading to deeper xylem layers over time. In both species, the bark removal tended to result in a small but non-significant increase in the percent loss of hydraulic conductivity compared with control intact branches 6 days after bark wounding (from 6 to 8-10% in both species). The bark wounding had no significant effects on midday leaf water potential, CO2 assimilation rates, stomatal conductance and water-use efficiency of the leaves of the current-year shoot, possibly due to limited impacts on xylem transport. The results of this study demonstrate that bark wounding induces limited but gradual embolism spreading. However, the impacts of bark wounding may not significantly limit water delivery to distal organs and leaf gas exchange at the scale of several days.
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Affiliation(s)
- Radek Jupa
- Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 5, Brno CZ-62500, Czech Republic
| | - Kamila Pokorná
- Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 5, Brno CZ-62500, Czech Republic
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6
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Chu C, Momayyezi M, Stobbs JA, Soolanayakanahally RY, McElrone AJ, Knipfer T. Drought-induced fiber water release and xylem embolism susceptibility of intact balsam poplar saplings. PHYSIOLOGIA PLANTARUM 2023; 175:e14040. [PMID: 37882281 DOI: 10.1111/ppl.14040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 08/31/2023] [Accepted: 09/27/2023] [Indexed: 10/27/2023]
Abstract
Balsam poplar (Populus balsamifera L.) is a widespread tree species in North America with significant ecological and economic value. However, little is known about the susceptibility of saplings to drought-induced embolism and its link to water release from surrounding xylem fibers. Questions remain regarding localized mechanisms that contribute to the survival of saplings in vivo of this species under drought. Using X-ray micro-computed tomography on intact saplings of genotypes Gillam-5 and Carnduff-9, we found that functional vessels are embedded in a matrix of water-filled fibers under well-watered conditions in both genotypes. However, water-depleted fibers started to appear under moderate drought stress while vessels remained water-filled in both genotypes. Drought-induced xylem embolism susceptibility was comparable between genotypes, and a greater frequency of smaller diameter vessels in GIL-5 did not increase embolism resistance in this genotype. Despite having smaller vessels and a total vessel number that was comparable to CAR-9, stomatal conductance was generally higher in GIL-5 compared to CAR-9. In conclusion, our in vivo data on intact saplings indicate that differences in embolism susceptibility are negligible between GIL-5 and CAR-9, and that fiber water release should be considered as a mechanism that contributes to the maintenance of vessel functional status in saplings of balsam poplar experiencing their first drought event.
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Affiliation(s)
- Cheyenne Chu
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mina Momayyezi
- Department of Viticulture and Enology, University of California, Davis, California, USA
| | | | | | - Andrew J McElrone
- Department of Viticulture and Enology, University of California, Davis, California, USA
- USDA-ARS, Crops Pathology and Genetics Research Unit, Davis, California, USA
| | - Thorsten Knipfer
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
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7
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O’Keefe K, Smith DD, McCulloh KA. Linking stem rehydration kinetics to hydraulic traits using a novel method and mechanistic model. ANNALS OF BOTANY 2023; 131:1121-1131. [PMID: 37232478 PMCID: PMC10457032 DOI: 10.1093/aob/mcad066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 05/22/2023] [Indexed: 05/27/2023]
Abstract
BACKGROUND Despite the recognized importance of hydraulic capacitance as a mechanism used by plants to maintain hydraulic functioning during high transpiration, characterizing the dynamics of capacitance remains a challenge. METHODS We used a novel 'two-balance method' to investigate relationships between stem rehydration kinetics and other hydraulic traits in multiple tree species, and we developed a model to explore stem rehydration kinetics further. KEY RESULTS We found that: (1) rehydration time constants and the amount of water uptake occurring during rehydration differed significantly across species; (2) time constants did not change with declining water potential (Ψ), while water uptake increased at lower Ψ in some species; (3) longer time constants were associated with lower wood density, higher capacitance and less negative stem pressures causing 50 % loss of hydraulic conductivity (P50); (4) greater water uptake occurred in stems with lower wood density and less negative P50 values; and (5) the model could estimate the total hydraulic resistance of the rehydration path, which cannot be measured directly. CONCLUSIONS Overall, the two-balance method can be used to examine rehydration dynamics quickly and thoroughly in detached woody stems. This method has the potential to improve our understanding of how capacitance functions across tree species, which is an often-overlooked component of whole-plant hydraulics.
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Affiliation(s)
- Kimberly O’Keefe
- Department of Botany, University of Wisconsin-Madison, Madison, WI 53706, USA
- Division of Biological Sciences, St. Edward’s University, Austin, TX 78704, USA
| | - Duncan D Smith
- Department of Botany, University of Wisconsin-Madison, Madison, WI 53706, USA
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8
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Martínez-Vilalta J, Poyatos R. Connecting the dots: concurrent assessment of water flows and pools to better understand plant responses to drought. TREE PHYSIOLOGY 2023; 43:1285-1289. [PMID: 37341378 DOI: 10.1093/treephys/tpad076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 06/08/2023] [Accepted: 06/15/2023] [Indexed: 06/22/2023]
Affiliation(s)
- Jordi Martínez-Vilalta
- CREAF, E08193 Bellaterra (Cerdanyola del Vallès), Catalonia, Spain
- Universitat Autònoma de Barcelona, E08193 Bellaterra (Cerdanyola del Vallès), Catalonia, Spain
| | - Rafael Poyatos
- CREAF, E08193 Bellaterra (Cerdanyola del Vallès), Catalonia, Spain
- Universitat Autònoma de Barcelona, E08193 Bellaterra (Cerdanyola del Vallès), Catalonia, Spain
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9
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Martín-Gómez P, Rodríguez-Robles U, Ogée J, Wingate L, Sancho-Knapik D, Peguero-Pina J, Dos Santos Silva JV, Gil-Pelegrín E, Pemán J, Ferrio JP. Contrasting stem water uptake and storage dynamics of water-saver and water-spender species during drought and recovery. TREE PHYSIOLOGY 2023; 43:1290-1306. [PMID: 36930058 DOI: 10.1093/treephys/tpad032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 03/01/2023] [Accepted: 03/07/2023] [Indexed: 06/18/2023]
Abstract
Drought is projected to occur more frequently and intensely in the coming decades, and the extent to which it will affect forest functioning will depend on species-specific responses to water stress. Aiming to understand the hydraulic traits and water dynamics behind water-saver and water-spender strategies in response to drought and recovery, we conducted a pot experiment with two species with contrasting physiological strategies, Scots pine (Pinus sylvestris L.) and Portuguese oak (Quercus faginea L.). We applied two cycles of soil drying and recovery and irrigated with isotopically different water to track fast changes in soil and stem water pools, while continuously measuring physiological status and xylem water content from twigs. Our results provide evidence for a tight link between the leaf-level response and the water uptake and storage patterns in the stem. The water-saver strategy of pines prevented stem dehydration by rapidly closing stomata which limited their water uptake during the early stages of drought and recovery. Conversely, oaks showed a less conservative strategy, maintaining transpiration and physiological activity under dry soil conditions, and consequently becoming more dehydrated at the stem level. We interpreted this dehydration as the release of water from elastic storage tissues as no major loss of hydraulic conductance occurred for this species. After soil rewetting, pines recovered pre-drought leaf water potential rapidly, but it took longer to replace the water from conductive tissues (slower labeling speed). In contrast, water-spender oaks were able to quickly replace xylem water during recovery (fast labeling speed), but it took longer to refill stem storage tissues, and hence to recover pre-drought leaf water potential. These different patterns in sap flow rates, speed and duration of the labeling reflected a combination of water-use and storage traits, linked to the leaf-level strategies in response to drought and recovery.
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Affiliation(s)
- Paula Martín-Gómez
- Joint Research Unit CTFC - AGROTECNIO - CERCA, Ctra de Sant Llorenç de Morunys, km 2, E-25280 Solsona, Lleida, Spain
| | - Ulises Rodríguez-Robles
- Departamento de Ecología y Recursos Naturales, Centro Universitario de la Costa Sur, Universidad de Guadalajara, Av. Independencia Nacional 151, Autlán de Navarro, 48900 Jalisco, México
| | - Jérôme Ogée
- Atmosphere Plant Soil Interactions Research Unit (UMR ISPA), Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), 71 Av. Edouard Bourlaux, F-33140 Villenave d'Ornon, France
| | - Lisa Wingate
- Atmosphere Plant Soil Interactions Research Unit (UMR ISPA), Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), 71 Av. Edouard Bourlaux, F-33140 Villenave d'Ornon, France
| | - Domingo Sancho-Knapik
- Departamento de Sistemas Agrícolas, Forestales y Medio Ambiente, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda. Montañana 930, E-50059 Zaragoza, Spain
| | - José Peguero-Pina
- Departamento de Sistemas Agrícolas, Forestales y Medio Ambiente, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda. Montañana 930, E-50059 Zaragoza, Spain
| | - José Victor Dos Santos Silva
- Departamento de Sistemas Agrícolas, Forestales y Medio Ambiente, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda. Montañana 930, E-50059 Zaragoza, Spain
| | - Eustaquio Gil-Pelegrín
- Departamento de Sistemas Agrícolas, Forestales y Medio Ambiente, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda. Montañana 930, E-50059 Zaragoza, Spain
| | - Jesús Pemán
- Department of Crop and Forest Sciences, Universitat de Lleida (UdL), Av. Alcalde Rovira Roure 191, 25198 Lleida, Spain
| | - Juan Pedro Ferrio
- Departamento de Sistemas Agrícolas, Forestales y Medio Ambiente, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda. Montañana 930, E-50059 Zaragoza, Spain
- Aragon Agency for Research and Development (ARAID), E-50018 Zaragoza, Spain
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10
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Ievinsh G. Water Content of Plant Tissues: So Simple That Almost Forgotten? PLANTS (BASEL, SWITZERLAND) 2023; 12:plants12061238. [PMID: 36986926 PMCID: PMC10058729 DOI: 10.3390/plants12061238] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 03/06/2023] [Accepted: 03/06/2023] [Indexed: 06/12/2023]
Abstract
The aim of the present review was to reconsider basic information about various functional aspects related to plant water content and provide evidence that the usefulness of measuring absolute water content in plant sciences is undervalued. First, general questions about water status in plants as well as methods for determining water content and their associated problems were discussed. After a brief overview of the structural organization of water in plant tissues, attention was paid to the water content of different parts of plants. Looking at the influence of environmental factors on plant water status, the differences caused by air humidity, mineral supply, biotic effects, salinity, and specific life forms (clonal and succulent plants) were analyzed. Finally, it was concluded that the expression of absolute water content on a dry biomass basis makes easily noticeable functional sense, but the physiological meaning and ecological significance of the drastic differences in plant water content need to be further elucidated.
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Affiliation(s)
- Gederts Ievinsh
- Department of Plant Physiology, Faculty of Biology, University of Latvia, 1 Jelgavas Str., LV-1004 Rīga, Latvia
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11
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Verslues PE, Bailey-Serres J, Brodersen C, Buckley TN, Conti L, Christmann A, Dinneny JR, Grill E, Hayes S, Heckman RW, Hsu PK, Juenger TE, Mas P, Munnik T, Nelissen H, Sack L, Schroeder JI, Testerink C, Tyerman SD, Umezawa T, Wigge PA. Burning questions for a warming and changing world: 15 unknowns in plant abiotic stress. THE PLANT CELL 2023; 35:67-108. [PMID: 36018271 PMCID: PMC9806664 DOI: 10.1093/plcell/koac263] [Citation(s) in RCA: 47] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 08/21/2022] [Indexed: 05/08/2023]
Abstract
We present unresolved questions in plant abiotic stress biology as posed by 15 research groups with expertise spanning eco-physiology to cell and molecular biology. Common themes of these questions include the need to better understand how plants detect water availability, temperature, salinity, and rising carbon dioxide (CO2) levels; how environmental signals interface with endogenous signaling and development (e.g. circadian clock and flowering time); and how this integrated signaling controls downstream responses (e.g. stomatal regulation, proline metabolism, and growth versus defense balance). The plasma membrane comes up frequently as a site of key signaling and transport events (e.g. mechanosensing and lipid-derived signaling, aquaporins). Adaptation to water extremes and rising CO2 affects hydraulic architecture and transpiration, as well as root and shoot growth and morphology, in ways not fully understood. Environmental adaptation involves tradeoffs that limit ecological distribution and crop resilience in the face of changing and increasingly unpredictable environments. Exploration of plant diversity within and among species can help us know which of these tradeoffs represent fundamental limits and which ones can be circumvented by bringing new trait combinations together. Better defining what constitutes beneficial stress resistance in different contexts and making connections between genes and phenotypes, and between laboratory and field observations, are overarching challenges.
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Affiliation(s)
| | - Julia Bailey-Serres
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521, USA
| | - Craig Brodersen
- School of the Environment, Yale University, New Haven, Connecticut 06511, USA
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, California 95616, USA
| | - Lucio Conti
- Department of Biosciences, University of Milan, Milan 20133, Italy
| | - Alexander Christmann
- School of Life Sciences, Technical University Munich, Freising-Weihenstephan 85354, Germany
| | - José R Dinneny
- Department of Biology, Stanford University, Stanford, California 94305, USA
| | - Erwin Grill
- School of Life Sciences, Technical University Munich, Freising-Weihenstephan 85354, Germany
| | - Scott Hayes
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University and Research, Wageningen 6708 PB, The Netherlands
| | - Robert W Heckman
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712, USA
| | - Po-Kai Hsu
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, La Jolla, California 92093, USA
| | - Thomas E Juenger
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712, USA
| | - Paloma Mas
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Barcelona 08193, Spain
- Consejo Superior de Investigaciones Científicas (CSIC), Barcelona 08028, Spain
| | - Teun Munnik
- Department of Plant Cell Biology, Green Life Sciences Cluster, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam NL-1098XH, The Netherlands
| | - Hilde Nelissen
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent 9052, Belgium
- VIB Center for Plant Systems Biology, Ghent 9052, Belgium
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, Institute of the Environment and Sustainability, University of California, Los Angeles, California 90095, USA
| | - Julian I Schroeder
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, La Jolla, California 92093, USA
| | - Christa Testerink
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University and Research, Wageningen 6708 PB, The Netherlands
| | - Stephen D Tyerman
- ARC Center Excellence, Plant Energy Biology, School of Agriculture Food and Wine, University of Adelaide, Adelaide, South Australia 5064, Australia
| | - Taishi Umezawa
- Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 6708 PB, Japan
| | - Philip A Wigge
- Leibniz-Institut für Gemüse- und Zierpflanzenbau, Großbeeren 14979, Germany
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam 14476, Germany
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12
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Casagrande Biasuz E, Kalcsits LA. Apple rootstocks affect functional leaf traits with consequential effects on carbon isotope composition and vegetative vigour. AOB PLANTS 2022; 14:plac020. [PMID: 35937547 PMCID: PMC9346634 DOI: 10.1093/aobpla/plac020] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 05/04/2022] [Indexed: 05/27/2023]
Abstract
Composite trees combine optimal traits from both the rootstock and the scion. Dwarfing rootstocks are commonly used to reduce shoot vigour and improve fruit quality and productivity. Although growth habits of different rootstocks have been clearly described, the underlying physiological traits affecting scion vigour are not well understood. Plant water status and stem water potential are strongly influenced by water supply and demand through the soil-plant-atmosphere continuum. In the scion, stomata regulate water loss and are essential to prevent hydraulic failure. Stomatal conductance influences leaf carbon isotope composition. Combined, the effects of reduced stomatal conductance and, consequently, carbon fixation may affect tree growth. These differences could also correspond to differences in scion vigour controlled by rootstock genotype. Here, vegetative growth, gas exchange, stem water potential and leaf δ13C were compared to determine how rootstocks affect scion water relations and whether these differences correspond to shoot vigour. There was a range in vigour among rootstocks by almost 2-fold. Net leaf carbon assimilation rates were lower in rootstocks with lower vigour. Rootstock vigour was closely associated with leaf gas exchange and stem water potential in the scion and was reflected in leaf δ13C signatures. Dwarfing was strongly affected by changes to plant water status induced by rootstock genotype and these changes are distinguishable when measuring leaf and stem δ13C composition. These observations indicate that scion water relations and leaf carbon isotope discrimination were affected by rootstock genotype. These results have implications for better understanding dwarfing mechanisms in apple rootstocks and the relationship with water-use traits.
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Affiliation(s)
- Erica Casagrande Biasuz
- Department of Horticulture, Washington State University, 1100 North Western Avenue, Wenatchee, WA 98801, USA
- WSU Tree Fruit Research and Extension Center, 1100 North Western Avenue, Wenatchee, WA 98801, USA
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13
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Li X, Xi B, Wu X, Choat B, Feng J, Jiang M, Tissue D. Unlocking Drought-Induced Tree Mortality: Physiological Mechanisms to Modeling. FRONTIERS IN PLANT SCIENCE 2022; 13:835921. [PMID: 35444681 PMCID: PMC9015645 DOI: 10.3389/fpls.2022.835921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 03/04/2022] [Indexed: 06/14/2023]
Abstract
Drought-related tree mortality has become a major concern worldwide due to its pronounced negative impacts on the functioning and sustainability of forest ecosystems. However, our ability to identify the species that are most vulnerable to drought, and to pinpoint the spatial and temporal patterns of mortality events, is still limited. Model is useful tools to capture the dynamics of vegetation at spatiotemporal scales, yet contemporary land surface models (LSMs) are often incapable of predicting the response of vegetation to environmental perturbations with sufficient accuracy, especially under stressful conditions such as drought. Significant progress has been made regarding the physiological mechanisms underpinning plant drought response in the past decade, and plant hydraulic dysfunction has emerged as a key determinant for tree death due to water shortage. The identification of pivotal physiological events and relevant plant traits may facilitate forecasting tree mortality through a mechanistic approach, with improved precision. In this review, we (1) summarize current understanding of physiological mechanisms leading to tree death, (2) describe the functionality of key hydraulic traits that are involved in the process of hydraulic dysfunction, and (3) outline their roles in improving the representation of hydraulic function in LSMs. We urge potential future research on detailed hydraulic processes under drought, pinpointing corresponding functional traits, as well as understanding traits variation across and within species, for a better representation of drought-induced tree mortality in models.
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Affiliation(s)
- Ximeng Li
- College of Life and Environmental Science, Minzu University of China, Beijing, China
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Benye Xi
- Ministry of Education Key Laboratory of Silviculture and Conservation, Beijing Forestry University, Beijing, China
| | - Xiuchen Wu
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, China
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Jinchao Feng
- College of Life and Environmental Science, Minzu University of China, Beijing, China
| | - Mingkai Jiang
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - David Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
- Global Centre for Land-based Innovation, Western Sydney University, Richmond, NSW, Australia
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14
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Mantova M, Herbette S, Cochard H, Torres-Ruiz JM. Hydraulic failure and tree mortality: from correlation to causation. TRENDS IN PLANT SCIENCE 2022; 27:335-345. [PMID: 34772610 DOI: 10.1016/j.tplants.2021.10.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 09/27/2021] [Accepted: 10/15/2021] [Indexed: 06/13/2023]
Abstract
Xylem hydraulic failure has been recognized as a pervasive factor in the triggering of drought-induced tree mortality. However, foundational evidence of the mechanistic link connecting hydraulic failure with living cell damage and tree death has not been identified yet, compromising our ability to predict mortality events. Meristematic cells are involved in the recovery of trees from drought, and focusing on their vitality and functionality after a drought event could provide novel information on the mechanistic link between hydraulic failure and drought-induced tree mortality. In this Opinion, we focus on the cell's critical hydration status for tree recovery from drought and how it links with the membrane integrity of the meristems.
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Affiliation(s)
- Marylou Mantova
- Université Clermont Auvergne, INRAE, PIAF, 63000 Clermont-Ferrand, France
| | - Stéphane Herbette
- Université Clermont Auvergne, INRAE, PIAF, 63000 Clermont-Ferrand, France
| | - Hervé Cochard
- Université Clermont Auvergne, INRAE, PIAF, 63000 Clermont-Ferrand, France
| | - José M Torres-Ruiz
- Université Clermont Auvergne, INRAE, PIAF, 63000 Clermont-Ferrand, France.
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15
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Weithmann G, Link RM, Banzragch BE, Würzberg L, Leuschner C, Schuldt B. Soil water availability and branch age explain variability in xylem safety of European beech in Central Europe. Oecologia 2022; 198:629-644. [PMID: 35212818 PMCID: PMC8956530 DOI: 10.1007/s00442-022-05124-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 01/24/2022] [Indexed: 12/17/2022]
Abstract
Xylem embolism resistance has been identified as a key trait with a causal relation to drought-induced tree mortality, but not much is known about its intra-specific trait variability (ITV) in dependence on environmental variation. We measured xylem safety and efficiency in 300 European beech (Fagus sylvatica L.) trees across 30 sites in Central Europe, covering a precipitation reduction from 886 to 522 mm year−1. A broad range of variables that might affect embolism resistance in mature trees, including climatic and soil water availability, competition, and branch age, were examined. The average P50 value varied by up to 1 MPa between sites. Neither climatic aridity nor structural variables had a significant influence on P50. However, P50 was less negative for trees with a higher soil water storage capacity, and positively related to branch age, while specific conductivity (Ks) was not significantly associated with either of these variables. The greatest part of the ITV for xylem safety and efficiency was attributed to random variability within populations. We conclude that the influence of site water availability on P50 and Ks is low in European beech, and that the high degree of within-population variability for P50, partly due to variation in branch age, hampers the identification of a clear environmental signal.
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Affiliation(s)
- Greta Weithmann
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany
| | - Roman M Link
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany.,Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Institute of Biological Sciences, University of Würzburg, Julius-von-Sachs-Platz, 97082, Würzburg, Germany
| | - Bat-Enerel Banzragch
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany
| | - Laura Würzberg
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany
| | - Christoph Leuschner
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany.,Centre for Biodiversity and Sustainable Land Use (CBL), University of Goettingen, 37075, Göttingen, Germany
| | - Bernhard Schuldt
- Plant Ecology, Albrecht Von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073, Göttingen, Germany. .,Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Institute of Biological Sciences, University of Würzburg, Julius-von-Sachs-Platz, 97082, Würzburg, Germany.
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16
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Sheridan RA, Nackley LL. Applying Plant Hydraulic Physiology Methods to Investigate Desiccation During Prolonged Cold Storage of Horticultural Trees. FRONTIERS IN PLANT SCIENCE 2022; 13:818769. [PMID: 35283873 PMCID: PMC8908214 DOI: 10.3389/fpls.2022.818769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 02/01/2022] [Indexed: 06/14/2023]
Abstract
Plant nursery production systems are a multi-billion-dollar, international, and horticultural industry that depends on storing and shipping live plants. The storage environment represents potentially desiccating and even fatal conditions for dormant, bareroot, and deciduous horticulture crops, like orchard trees, forestry trees, ornamental trees, and grapevines. When tree mortality is considered within a plant hydraulic framework, plants experiencing water stress are thought to ultimately die from hydraulic failure or carbon starvation. We hypothesized that the hydraulic framework can be applied to stored crops to determine if hydraulic failure or carbon starvation could be attributed to mortality. We used deciduous trees as model species because they are important horticultural crops and provide a diversity of hydraulic strategies. We selected cultivars from six genera: Acer, Amelanchier, Gleditsia, Gymnocladus, Malus, and Quercus. For each cultivar, we measured stem hydraulic conductance and vulnerability to embolism. On a weekly basis for 14 weeks (March-June), we removed trees of each cultivar from cold storage (1-2°C). Each week and for each cultivar, we measured stem water potential and water content (n = 7) and planted trees to track survival and growth (n = 10). At three times during this period, we also measured non-structural carbohydrates. Our results showed that for four cultivars (Acer, Amelanchier, Malus, and Quercus), the stem water potentials measured in trees removed from storage did not exceed stem P 50, the water potential at which 50% of stem hydraulic conductivity is lost. This suggests that the water transport system remains intact during storage. For two cultivars (Gleditsia and Gymnocladus), the water potential measured on trees out of storage exceeded stem P 50, yet planted trees from all weeks survived and grew. In the 14 weeks, there were no significant changes or directional trends in stem water potential, water content, or NSC for most cultivars, with a few exceptions. Overall, the results show that the trees did not experience detrimental water relations or carbon starvation thresholds. Our results suggest that many young deciduous trees are resilient to conditions caused by prolonged dormancy and validate the current storage methods. This experiment provides an example of how a mechanistically based understanding of physiological responses can inform cold storage regimes in nursery tree production.
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Affiliation(s)
| | - Lloyd L. Nackley
- North Willamette Research and Extension Center, Oregon State University, Corvallis, OR, United States
- Department of Horticulture, Oregon State University, Corvallis, OR, United States
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17
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Barbeta A, Burlett R, Martín-Gómez P, Fréjaville B, Devert N, Wingate L, Domec JC, Ogée J. Evidence for distinct isotopic compositions of sap and tissue water in tree stems: consequences for plant water source identification. THE NEW PHYTOLOGIST 2022; 233:1121-1132. [PMID: 34767646 DOI: 10.1111/nph.17857] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 11/04/2021] [Indexed: 06/13/2023]
Abstract
The long-standing hypothesis that the isotopic composition of plant stem water reflects that of source water is being challenged by studies reporting bulk water from woody stems with an isotopic composition that cannot be attributed to any potential water source. The mechanism behind such source-stem water isotopic offsets is still poorly understood. Using a novel technique to extract selectively sap water from xylem conduits, we show that, in cut stems and potted plants, the isotopic composition of sap water reflects that of irrigation water, demonstrating unambiguously that no isotopic fractionation occurs during root water uptake or sap water extraction. By contrast, water in nonconductive xylem tissues is always depleted in deuterium compared with sap water, irrespective of wood anatomy. Previous studies have shown that isotopic heterogeneity also exists in soils at the pore scale in which water adsorbed onto soil particles is more depleted in deuterium than unbound water. Data collected at a riparian forest indicated that sap water matches best unbound soil water from depth below -70 cm, while bulk stem and soil water differ markedly. We conclude that source-stem isotopic offsets can be explained by micrometre-scale heterogeneity in the isotope ratios of water within woody stems and soil micro-pores.
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Affiliation(s)
- Adrià Barbeta
- INRAE, Bordeaux Sciences Agro, ISPA, Villenave d'Ornon, 33140, France
- BEECA, Universitat de Barcelona, Barcelona, Catalonia, 08028, Spain
| | - Régis Burlett
- Université de Bordeaux, INRAE, BIOGECO, Pessac, 33615, France
| | | | | | - Nicolas Devert
- INRAE, Bordeaux Sciences Agro, ISPA, Villenave d'Ornon, 33140, France
| | - Lisa Wingate
- INRAE, Bordeaux Sciences Agro, ISPA, Villenave d'Ornon, 33140, France
| | | | - Jérôme Ogée
- INRAE, Bordeaux Sciences Agro, ISPA, Villenave d'Ornon, 33140, France
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18
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Lauriks F, Salomón RL, De Roo L, Goossens W, Leroux O, Steppe K. Limited plasticity of anatomical and hydraulic traits in aspen trees under elevated CO2 and seasonal drought. PLANT PHYSIOLOGY 2022; 188:268-284. [PMID: 34718790 PMCID: PMC8774844 DOI: 10.1093/plphys/kiab497] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 09/28/2021] [Indexed: 06/13/2023]
Abstract
The timing of abiotic stress elicitors on wood formation largely affects xylem traits that determine xylem efficiency and vulnerability. Nonetheless, seasonal variability of elevated CO2 (eCO2) effects on tree functioning under drought remains largely unknown. To address this knowledge gap, 1-year-old aspen (Populus tremula L.) trees were grown under ambient (±445 ppm) and elevated (±700 ppm) CO2 and exposed to an early (spring/summer 2019) or late (summer/autumn 2018) season drought event. Stomatal conductance and stem shrinkage were monitored in vivo as xylem water potential decreased. Additional trees were harvested for characterization of wood anatomical traits and to determine vulnerability and desorption curves via bench dehydration. The abundance of narrow vessels decreased under eCO2 only during the early season. At this time, xylem vulnerability to embolism formation and hydraulic capacitance during severe drought increased under eCO2. Contrastingly, stomatal closure was delayed during the late season, while hydraulic vulnerability and capacitance remained unaffected under eCO2. Independently of the CO2 treatment, elastic, and inelastic water pools depleted simultaneously after 50% of complete stomatal closure. Our results suggest that the effect of eCO2 on drought physiology and wood traits are small and variable during the growing season and question a sequential capacitive water release from elastic and inelastic pools as drought proceeds.
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Affiliation(s)
- Fran Lauriks
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium
| | - Roberto Luis Salomón
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium
- Grupo de Investigación Sistemas Naturales e Historia Forestal, Universidad Politécnica de Madrid, Madrid 28040, Spain
| | - Linus De Roo
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium
| | - Willem Goossens
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium
| | - Olivier Leroux
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium
- Department of Biology, Faculty of Sciences, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, 9000 Ghent, Belgium
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19
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Ganthaler A, Bär A, Dämon B, Losso A, Nardini A, Dullin C, Tromba G, von Arx G, Mayr S. Alpine dwarf shrubs show high proportions of nonfunctional xylem: Visualization and quantification of species-specific patterns. PLANT, CELL & ENVIRONMENT 2022; 45:55-68. [PMID: 34783044 DOI: 10.1111/pce.14226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 07/15/2021] [Accepted: 07/15/2021] [Indexed: 06/13/2023]
Abstract
Xylem conductive capacity is a key determinant of plant hydraulic function and intimately linked to photosynthesis and productivity, but can be impeded by temporary or permanent conduit dysfunctions. Here we show that persistent xylem dysfunctions in unstressed plants are frequent in Alpine dwarf shrubs and occur in various but species-specific cross-sectional patterns. Combined synchrotron micro-computed tomography (micro-CT) imaging, xylem staining, and flow measurements in saturated samples of six widespread Ericaceae species evidence a high proportion (19%-50%) of hydraulically nonfunctional xylem areas in the absence of drought stress, with regular distribution of dysfunctions between or within growth rings. Dysfunctions were only partly reversible and reduced the specific hydraulic conductivity to 1.38 to 3.57 ×10-4 m2 s-1 MPa-1 . Decommission of inner growth rings was clearly related to stem age and a higher vulnerability to cavitation of older rings, while the high proportion of nonfunctional conduits in each annual ring needs further investigations. The lower the xylem fraction contributing to the transport function, the higher was the hydraulic efficiency of conducting xylem areas. Improved understanding of the functional lifespan of xylem elements and the prevalence and nature of dysfunctions is critical to correctly assess structure-function relationships and whole-plant hydraulic strategies.
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Affiliation(s)
- Andrea Ganthaler
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Andreas Bär
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Birgit Dämon
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Adriano Losso
- Department of Botany, University of Innsbruck, Innsbruck, Austria
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
| | - Andrea Nardini
- Dipartimento di Scienze della Vita, Università di Trieste, Trieste, Italy
| | - Christian Dullin
- Elettra-Sincrotrone Trieste, Basovizza, Italy
- Institute for Diagnostic and Interventional Radiology, University Medical Center, Göttingen, Germany
- Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
- Diagnostic and Interventional Radiology, University Hospital, Heidelberg, Germany
| | | | - Georg von Arx
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
| | - Stefan Mayr
- Department of Botany, University of Innsbruck, Innsbruck, Austria
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20
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Williams CB, Reese Næsborg R, Ambrose AR, Baxter WL, Koch GW, Dawson TE. The dynamics of stem water storage in the tops of Earth's largest trees-Sequoiadendron giganteum. TREE PHYSIOLOGY 2021; 41:2262-2278. [PMID: 34104960 DOI: 10.1093/treephys/tpab078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 05/31/2021] [Indexed: 06/12/2023]
Abstract
Water stored in tree stems (i.e., trunks and branches) is an important contributor to transpiration that can improve photosynthetic carbon gain and reduce the probability of cavitation. However, in tall trees, the capacity to store water may decline with height because of chronically low water potentials associated with the gravitational potential gradient. We quantified the importance of elastic stem water storage in the top 5-6 m of large (4.2-5.0 m diameter at breast height, 82.1-86.3 m tall) Sequoiadendron giganteum (Lindley) J. Buchholz (giant sequoia) trees using a combination of architectural measurements and automated sensors that monitored summertime diel rhythms in sap flow, stem diameter and water potential. Stem water storage contributed 1.5-1.8% of water transpired at the tree tops, and hydraulic capacitance ranged from 2.6 to 4.1 l MPa-1 m-3. These values, which are considerably smaller than reported for shorter trees, may be associated with persistently low water potentials imposed by gravity and could indicate a trend of decreasing water storage dynamics with height in tree. Branch diameter contraction and expansion consistently and substantially lagged behind fluxes in water potential and sap flow, which occurred in sync. This lag suggests that the inner bark, which consists mostly of live secondary phloem tissue, was an important hydraulic capacitor, and that hydraulic resistance between xylem and phloem retards water transfer between these tissues. We also measured tree-base sap flux, which lagged behind that measured in trunks near the tree tops, indicating additional storage in the large trunks between these measurement positions. Whole-tree sap flow ranged from 2227 to 3752 l day-1, corroborating previous records for similar-sized giant sequoia and representing the largest yet reported for any individual tree. Despite such extraordinarily high daily water use, we estimate that water stored in tree-top stems contributes minimally to transpiration on typical summer days.
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Affiliation(s)
- Cameron B Williams
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- Channel Islands National Park, Ventura, CA 93001, USA
- Santa Barbara Botanic Garden, Santa Barbara, CA 93105, USA
| | - Rikke Reese Næsborg
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- Santa Barbara Botanic Garden, Santa Barbara, CA 93105, USA
| | - Anthony R Ambrose
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- The Marmot Society, South Lake Tahoe, CA 96150, USA
| | - Wendy L Baxter
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- The Marmot Society, South Lake Tahoe, CA 96150, USA
| | - George W Koch
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Todd E Dawson
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
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21
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Gessler A. Water transport in trees-the importance of radial and circumferential transport. TREE PHYSIOLOGY 2021; 41:2245-2247. [PMID: 34617110 DOI: 10.1093/treephys/tpab131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/01/2021] [Accepted: 09/27/2021] [Indexed: 06/13/2023]
Affiliation(s)
- Arthur Gessler
- Institute of Terrestrial Ecosystems (ITES), Department of Environmental Systems Science, ETH Zurich, Universitaetstrasse 16, 8092 Zurich, Switzerland
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22
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Baer AB, Fickle JC, Medina J, Robles C, Pratt RB, Jacobsen AL. Xylem biomechanics, water storage, and density within roots and shoots of an angiosperm tree species. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:7984-7997. [PMID: 34410349 DOI: 10.1093/jxb/erab384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 08/17/2021] [Indexed: 06/13/2023]
Abstract
Xylem is a complex tissue that forms the bulk of tree bodies and has several functions, including to conduct water, store water and nutrients, and biomechanically support the plant body. We examined how xylem functional traits varied at different positions within 9-year-old Populus balsamifera subsp. trichocarpa. Whole trees were excavated, and xylem samples were collected at 1-m increments along the main root-to-shoot axis of six trees, from root tip to shoot tip. We examined biomechanical and water-storage traits of the xylem, including using a non-invasive imaging technique to examine water content within long, intact branches (high-resolution computed tomography; microCT). Xylem density, strength, and stiffness were greater in shoots than roots. Along the main root-to-shoot axis, xylem strength and stiffness were greatest at shoot tips, and the tissue became linearly weaker and less stiff down the plant and through the root. Roots had greater water storage with lower biomechanical support, and shoots had biomechanically stronger and stiffer xylem with lower water storage. These findings support trade-offs among xylem functions between roots and shoots. Understanding how xylem functions differ throughout tree bodies is important in understanding whole-tree functioning and how terrestrial plants endure numerous environmental challenges over decades of growth.
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Affiliation(s)
- Alex B Baer
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
| | - Jaycie C Fickle
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
| | - Jackeline Medina
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
| | - Catherine Robles
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
| | - R Brandon Pratt
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
| | - Anna L Jacobsen
- Department of Biology, California State University, Bakersfield, CA, 93311, USA
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23
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Treydte K, Lehmann MM, Wyczesany T, Pfautsch S. Radial and axial water movement in adult trees recorded by stable isotope tracing. TREE PHYSIOLOGY 2021; 41:2248-2261. [PMID: 34100071 DOI: 10.1093/treephys/tpab080] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 05/31/2021] [Indexed: 06/12/2023]
Abstract
The capacity of trees to release water from storage compartments into the transpiration stream can mitigate damage to hydraulic functioning. However, the location of these 'transient' water sources and also the pathways of water movement other than vertical through tree stems still remain poorly understood. We conducted an experiment on two tree species in a common garden in eastern Australia that naturally grow in regions of high (Eucalyptus tereticornis, 'Red Gum') and low (Eucalyptus sideroxylon, 'Ironbark') annual precipitation rates. Deuterium-enriched water (1350% label strength) was directly introduced into the transpiration stream of three trees per species for four consecutive days. Subsequently, the trees were felled, woody tissue samples were collected from different heights and azimuthal positions of the stems, and stable isotope ratios were determined on the water extracted from all samples. The presence/absence of the tracer along the radial and vertical stem axes in combination with xylem hydraulic properties inferred from sapflow, leaf and stem water potentials, wood moisture contents and anatomical sapwood characteristics elucidated species-specific patterns of short-term stem water storage and movement. The distribution of water isotopes at natural abundance among woody tissues indicated systematic differences with highest values of sapwood water and lower values in inner bark and heartwood. Presence of tracer in water of the inner bark highlighted the importance of this tissue as capacitor. Although injected at the northern side of stems, tracer was also discovered at the southern side, providing empirical evidence for circumferential flow in sapwood, particularly of Ironbark. Greater vertical water transport in Red Gum compared with more radial and circumferential water transport in Ironbark were associated with species-specific sapwood anatomy. Our study highlights the value of combining information from stable isotope tracers and wood anatomy to investigate patterns of water transport and storage of tall trees in situ.
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Affiliation(s)
- Kerstin Treydte
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow, and Landscape Research WSL, 8903 Birmensdorf, Switzerland
| | - Marco M Lehmann
- Research Unit Forest Dynamics, Swiss Federal Institute for Forest, Snow, and Landscape Research WSL, 8903 Birmensdorf, Switzerland
| | - Tomasz Wyczesany
- Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, NSW 2007, Australia
| | - Sebastian Pfautsch
- Hawkesbury Institute for the Environment, University of Western Sydney, Locked Bag 1797, Penrith, NSW 2751, Australia
- Urban Studies, School of Social Sciences, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
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Słupianek A, Dolzblasz A, Sokołowska K. Xylem Parenchyma-Role and Relevance in Wood Functioning in Trees. PLANTS (BASEL, SWITZERLAND) 2021; 10:1247. [PMID: 34205276 PMCID: PMC8235782 DOI: 10.3390/plants10061247] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/11/2021] [Accepted: 06/16/2021] [Indexed: 12/11/2022]
Abstract
Woody plants are characterised by a highly complex vascular system, wherein the secondary xylem (wood) is responsible for the axial transport of water and various substances. Previous studies have focused on the dead conductive elements in this heterogeneous tissue. However, the living xylem parenchyma cells, which constitute a significant functional fraction of the wood tissue, have been strongly neglected in studies on tree biology. Although there has recently been increased research interest in xylem parenchyma cells, the mechanisms that operate in these cells are poorly understood. Therefore, the present review focuses on selected roles of xylem parenchyma and its relevance in wood functioning. In addition, to elucidate the importance of xylem parenchyma, we have compiled evidence supporting the hypothesis on the significance of parenchyma cells in tree functioning and identified the key unaddressed questions in the field.
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Affiliation(s)
- Aleksandra Słupianek
- Department of Plant Developmental Biology, Faculty of Biological Sciences, University of Wrocław, Kanonia 6/8, 50-328 Wrocław, Poland; (A.D.); (K.S.)
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25
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Ziemińska K, Rosa E, Gleason SM, Holbrook NM. Wood day capacitance is related to water content, wood density, and anatomy across 30 temperate tree species. PLANT, CELL & ENVIRONMENT 2020; 43:3048-3067. [PMID: 32935340 DOI: 10.1111/pce.13891] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 09/05/2020] [Accepted: 09/07/2020] [Indexed: 06/11/2023]
Abstract
Water released from wood during transpiration (capacitance) can meaningfully affect daily water use and drought response. To provide context for better understanding of capacitance mechanisms, we investigated links between capacitance and wood anatomy. On twigs of 30 temperate angiosperm tree species, we measured day capacitance (between predawn and midday), water content, wood density, and anatomical traits, that is, vessel dimensions, tissue fractions, and vessel-tissue contact fractions (fraction of vessel circumference in contact with other tissues). Across all species, wood density (WD) and predawn lumen volumetric water content (VWCL-pd ) together were the strongest predictors of day capacitance (r2adj = .44). Vessel-tissue contact fractions explained an additional ~10% of the variation in day capacitance. Regression models were not improved by including tissue lumen fractions. Among diffuse-porous species, VWCL-pd and vessel-ray contact fraction together were the best predictors of day capacitance, whereas among semi/ring-porous species, VWCL-pd , WD and vessel-fibre contact fraction were the best predictors. At predawn, wood was less than fully saturated for all species (lumen relative water content = 0.52 ± 0.17). Our findings imply that day capacitance depends on the amount of stored water, tissue connectivity and the bulk wood properties arising from WD (e.g., elasticity), rather than the fraction of any particular tissue.
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Affiliation(s)
- Kasia Ziemińska
- Arnold Arboretum of Harvard University, Boston, Massachusetts, USA
- Department of Plant Ecology and Evolution, Uppsala University, Uppsala, Sweden
| | - Emily Rosa
- Department of Biology, Sonoma State University, Rohnert Park, California, USA
| | - Sean M Gleason
- United States Department of Agriculture - Agricultural Research Service, Water Management and Systems Research Unit, Fort Collins, Colorado, USA
| | - N Michele Holbrook
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
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Knipfer T, Bambach N, Hernandez MI, Bartlett MK, Sinclair G, Duong F, Kluepfel DA, McElrone AJ. Predicting Stomatal Closure and Turgor Loss in Woody Plants Using Predawn and Midday Water Potential. PLANT PHYSIOLOGY 2020; 184:881-894. [PMID: 32764130 PMCID: PMC7536669 DOI: 10.1104/pp.20.00500] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/21/2020] [Indexed: 05/03/2023]
Abstract
Knowledge about physiological stress thresholds provides crucial information about plant performance and survival under drought. In this study, we report on the triphasic nature of the relationship between plant water potential (Ψ) at predawn and midday and describe a method that predicts Ψ at stomatal closure and turgor loss exclusively from this water potential curve (WP curve). The method is based on a piecewise linear regression model that was developed to predict the boundaries (termed Θ1 and Θ2) separating the three phases of the curve and corresponding slope values. The method was tested for three economically important woody species. For all species, midday Ψ was much more negative than predawn Ψ during phase I (mild drought), reductions in midday Ψ were minor while predawn Ψ continued to decline during phase II (moderate drought), and midday and predawn Ψ reached similar values during phase III (severe drought). Corresponding measurement of leaf gas exchange indicated that boundary Θ1 between phases I and II coincided with Ψ at stomatal closure. Data from pressure-volume curves demonstrated that boundary Θ2 between phases II and III predicted Ψ at leaf turgor loss. The WP curve method described here is an advanced application of the Scholander-type pressure chamber to categorize plant dehydration under drought into three distinct phases and to predict Ψ thresholds of stomatal closure and turgor loss.
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Affiliation(s)
- Thorsten Knipfer
- Department of Viticulture and Enology, University of California, Davis, California 95616
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Nicolas Bambach
- Department of Viticulture and Enology, University of California, Davis, California 95616
| | - M Isabel Hernandez
- Department of Viticulture and Enology, University of California, Davis, California 95616
| | - Megan K Bartlett
- Department of Viticulture and Enology, University of California, Davis, California 95616
| | - Gabriela Sinclair
- Department of Viticulture and Enology, University of California, Davis, California 95616
| | - Fiona Duong
- Department of Viticulture and Enology, University of California, Davis, California 95616
| | - Daniel A Kluepfel
- United States Department of Agriculture-Agricultural Research Service, Crops Pathology and Genetics Research Unit, Davis, California 95616
| | - Andrew J McElrone
- Department of Viticulture and Enology, University of California, Davis, California 95616
- United States Department of Agriculture-Agricultural Research Service, Crops Pathology and Genetics Research Unit, Davis, California 95616
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Skelton R. Stem Diameter Fluctuations Provide a New Window into Plant Water Status and Function. PLANT PHYSIOLOGY 2020; 183:1414-1415. [PMID: 32747488 PMCID: PMC7401123 DOI: 10.1104/pp.20.00897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Affiliation(s)
- Robert Skelton
- South African Environmental Observation Network, Claremont 7735, South Africa
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28
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Yazaki K, Levia DF, Takenouchi A, Watanabe M, Kabeya D, Miki NH, Taneda H, Ogasa MY, Oguro M, Saiki S, Tobita H, Fukuda K. Imperforate tracheary elements and vessels alleviate xylem tension under severe dehydration: insights from water release curves for excised twigs of three tree species. AMERICAN JOURNAL OF BOTANY 2020; 107:1122-1135. [PMID: 32779767 PMCID: PMC7496847 DOI: 10.1002/ajb2.1518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 05/20/2020] [Indexed: 06/11/2023]
Abstract
PREMISE Water stored in the xylem of woody plants is important for supporting the transpiration stream under prolonged drought, yet the source of stored water within the xylem during drought remains unclear. Insights into xylem water utilization during drought will uncover the adaptation strategies of the test species to stress. METHODS To fill the existing knowledge gap, we excised twigs of Abies firma (Japanese fir, conifer), Cercidiphyllum japonicum (katsura tree, diffuse-porous) and Quercus serrata (konara oak, ring-porous) to quantify interspecific variation of water transfer in xylem corresponding with increasing cumulative water release (CWR) using micro x-ray computed tomography and cryo-SEM. RESULTS For all species studied, the main components of water storage within the operating range of water potential were not living cells but cavitation release and capillaries. Abies firma maintained water in the earlywood-like cells, for possible maintenance of the transpiration stream. Cercidiphyllum japonicum maintained water in its vessels over 200 kg m-3 of CWR, while Q. serrata lost most of its water in vessels with increasing CWR up to 100 kg m-3 . Cercidiphyllum japonicum exhibited a higher water storage capacity than Q. serrata. Under high CWR, narrow conduits stored xylem water in C. japonicum and imperforate tracheary elements in Q. serrata. CONCLUSIONS Among the species examined, increasing CWR appears to indicate differential utilization of stored water in relation to variation of xylem structure, thereby providing insight into the interspecific responses of tree species to drought.
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Affiliation(s)
- Kenichi Yazaki
- Department of Plant EcologyForestry and Forest Products Research Institute (FFPRI)TsukubaIbaraki305‐8687Japan
| | - Delphis F. Levia
- Departments of Geography & Spatial Sciences and Plant & Soil SciencesUniversity of DelawareNewarkDE19716USA
| | - Akiko Takenouchi
- Research Center for Structural MaterialsNational Institute of Materials Science (NIMS)TsukubaIbaraki305‐0047Japan
| | - Makoto Watanabe
- Research Center for Structural MaterialsNational Institute of Materials Science (NIMS)TsukubaIbaraki305‐0047Japan
| | - Daisuke Kabeya
- Department of Plant EcologyForestry and Forest Products Research Institute (FFPRI)TsukubaIbaraki305‐8687Japan
| | - Naoko H. Miki
- Graduate School of Environmental and Life ScienceOkayama UniversityOkayama700‐8530Japan
| | - Haruhiko Taneda
- Graduate School of ScienceThe University of TokyoTokyo113‐0033Japan
| | - Mayumi Y. Ogasa
- Kansai Research CenterForestry and Forest Products Research Institute (FFPRI)KyotoKyoto612‐0855Japan
| | - Michio Oguro
- Department of Forest VegetationForestry and Forest Products Research Institute (FFPRI)TsukubaIbaraki305‐8687Japan
| | - Shin‐Taro Saiki
- Department of Plant EcologyForestry and Forest Products Research Institute (FFPRI)TsukubaIbaraki305‐8687Japan
| | - Hiroyuki Tobita
- Department of Plant EcologyForestry and Forest Products Research Institute (FFPRI)TsukubaIbaraki305‐8687Japan
| | - Kenji Fukuda
- Graduate School of Agricultural and Life SciencesThe University of TokyoTokyo113‐8657Japan
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29
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Salomón RL, Steppe K, Ourcival JM, Villers S, Rodríguez-Calcerrada J, Schapman R, Limousin JM. Hydraulic acclimation in a Mediterranean oak subjected to permanent throughfall exclusion results in increased stem hydraulic capacitance. PLANT, CELL & ENVIRONMENT 2020; 43:1528-1544. [PMID: 32154937 DOI: 10.1111/pce.13751] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 02/28/2020] [Accepted: 03/02/2020] [Indexed: 06/10/2023]
Abstract
Stem water storage capacity and hydraulic capacitance (CS ) play a crucial role in tree survival under drought-stress. To investigate whether CS adjusts to increasing water deficit, variation in stem water content (StWC) was monitored in vivo for 2 years and related to periodical measurements of tree water potential in Mediterranean Quercus ilex trees subjected either to permanent throughfall exclusion (TE) or to control conditions. Seasonal reductions in StWC were larger in TE trees relative to control ones, resulting in greater seasonal CS (154 and 80 kg m-3 MPa-1 , respectively), but only during the first phase of the desorption curve, when predawn water potential was above -1.1 MPa. Below this point, CS decreased substantially and did not differ between treatments (<20 kg m-3 MPa-1 ). The allometric relationship between tree diameter and sapwood area, measured via electrical resistivity tomography, was not affected by TE. Our results suggest that (a) CS response to water deficit in the drought-tolerant Q. ilex might be more important to optimize carbon gain during well-hydrated periods than to prevent drought-induced embolism formation during severe drought stress, and (b) enhanced CS during early summer does not result from proportional increases in sapwood volume, but mostly from increased elastic water.
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Affiliation(s)
- Roberto L Salomón
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Jean M Ourcival
- Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), CEFE UMR 5175, CNRS, Univ Montpellier, Univ Paul Valéry Montpellier 3, EPHE, IRD, Montpellier Cedex 5, France
| | - Selwyn Villers
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | | | - Roderick Schapman
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Jean M Limousin
- Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), CEFE UMR 5175, CNRS, Univ Montpellier, Univ Paul Valéry Montpellier 3, EPHE, IRD, Montpellier Cedex 5, France
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30
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Skelton R, Diaz J. Quantifying losses of plant hydraulic function: seeing the forest, the trees and the xylem. TREE PHYSIOLOGY 2020; 40:285-289. [PMID: 31972024 DOI: 10.1093/treephys/tpz141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/11/2019] [Accepted: 12/18/2019] [Indexed: 06/10/2023]
Affiliation(s)
- Robert Skelton
- South African Environmental Observation Network, Fynbos Node, CBC Building, Rhodes Drive, Newlands, 7735, Cape Town, South Africa
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Jessica Diaz
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA, 94720, USA
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31
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Bouda M, Windt CW, McElrone AJ, Brodersen CR. In vivo pressure gradient heterogeneity increases flow contribution of small diameter vessels in grapevine. Nat Commun 2019; 10:5645. [PMID: 31822680 DOI: 10.17605/osf.io/ey2tj] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 11/19/2019] [Indexed: 05/26/2023] Open
Abstract
Leaves lose approximately 400 H2O molecules for every 1 CO2 gained during photosynthesis. Most long-distance water transport in plants, or xylem sap flow, serves to replace this water to prevent desiccation. Theory predicts that the largest vessels contribute disproportionately to overall sap flow because flow in pipe-like systems scales with the fourth power of radius. Here, we confront these theoretical flow predictions for a vessel network reconstructed from X-ray μCT imagery with in vivo flow MRI observations from the same sample of a first-year grapevine stem. Theoretical flow rate predictions based on vessel diameters are not supported. The heterogeneity of the vessel network gives rise to transverse pressure gradients that redirect flow from wide to narrow vessels, reducing the contribution of wide vessels to sap flow by 15% of the total. Our results call for an update of the current working model of the xylem to account for its heterogeneity.
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Affiliation(s)
- Martin Bouda
- School of Forestry & Environmental Studies, Yale University, 195 Prospect St., New Haven, CT, 06511, USA.
- Institute of Botany of the Czech Academy of Sciences, Zámek 1, 25243, Průhonice, Czech Republic.
| | - Carel W Windt
- IBG-2: Plant Sciences, Forschungszentrum Jülich, Leo Brandt Straße 1, 52428, Jülich, Germany
| | - Andrew J McElrone
- Department of Viticulture & Enology, University of California, 595 Hilgard Ln, Davis, CA, 95616, USA
- USDA-ARS, Crops Pathology and Genetics Research Unit, Davis, CA, USA
| | - Craig R Brodersen
- School of Forestry & Environmental Studies, Yale University, 195 Prospect St., New Haven, CT, 06511, USA
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32
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Bouda M, Windt CW, McElrone AJ, Brodersen CR. In vivo pressure gradient heterogeneity increases flow contribution of small diameter vessels in grapevine. Nat Commun 2019; 10:5645. [PMID: 31822680 PMCID: PMC6904565 DOI: 10.1038/s41467-019-13673-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 11/19/2019] [Indexed: 11/16/2022] Open
Abstract
Leaves lose approximately 400 H2O molecules for every 1 CO2 gained during photosynthesis. Most long-distance water transport in plants, or xylem sap flow, serves to replace this water to prevent desiccation. Theory predicts that the largest vessels contribute disproportionately to overall sap flow because flow in pipe-like systems scales with the fourth power of radius. Here, we confront these theoretical flow predictions for a vessel network reconstructed from X-ray μCT imagery with in vivo flow MRI observations from the same sample of a first-year grapevine stem. Theoretical flow rate predictions based on vessel diameters are not supported. The heterogeneity of the vessel network gives rise to transverse pressure gradients that redirect flow from wide to narrow vessels, reducing the contribution of wide vessels to sap flow by 15% of the total. Our results call for an update of the current working model of the xylem to account for its heterogeneity. Plants require long-distance water transport to avoid desiccation. Here, via μCT and MRI of grapevine stem, Bouda et al. show evidence of pressure gradient heterogeneity and flow redirection from wide to narrow vessels that suggests narrow vessels contribute more to xylem sap flow than previously appreciated.
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Affiliation(s)
- Martin Bouda
- School of Forestry & Environmental Studies, Yale University, 195 Prospect St., New Haven, CT, 06511, USA. .,Institute of Botany of the Czech Academy of Sciences, Zámek 1, 25243, Průhonice, Czech Republic.
| | - Carel W Windt
- IBG-2: Plant Sciences, Forschungszentrum Jülich, Leo Brandt Straße 1, 52428, Jülich, Germany
| | - Andrew J McElrone
- Department of Viticulture & Enology, University of California, 595 Hilgard Ln, Davis, CA, 95616, USA.,USDA-ARS, Crops Pathology and Genetics Research Unit, Davis, CA, USA
| | - Craig R Brodersen
- School of Forestry & Environmental Studies, Yale University, 195 Prospect St., New Haven, CT, 06511, USA
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33
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Skelton R. Of Storage and Stems: Examining the Role of Stem Water Storage in Plant Water Balance. PLANT PHYSIOLOGY 2019; 179:1433-1434. [PMID: 30940735 PMCID: PMC6446748 DOI: 10.1104/pp.19.00057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Affiliation(s)
- Robert Skelton
- Department of Integrative Biology, University of California, Berkeley, California 94707
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