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West AG, Atkins K, van Blerk JJ, Skelton RP. Assessing vulnerability to embolism and hydraulic safety margins in reed-like Restionaceae. PLANT BIOLOGY (STUTTGART, GERMANY) 2024; 26:633-646. [PMID: 38588329 DOI: 10.1111/plb.13644] [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: 11/30/2023] [Accepted: 03/12/2024] [Indexed: 04/10/2024]
Abstract
The African Restionaceae (Poales), the dominant graminoid layer in the megadiverse Cape Floristic Region of South Africa, are distributed across a wide range of moisture availability, yet currently there is very little known about the underlying hydraulics of this group. We tested two methods for measuring culm vulnerability to embolism, the optical and pneumatic methods, in three species of Cannomois ranging in habitat from semi-riparian (Cannomois virgata) to dryland (Cannomois parviflora and C. congesta). Estimates of culm xylem vulnerability were coupled with measures of turgor loss point (ΨTLP) and minimum field water potential (ΨMD) to assess hydraulic safety margins. The optical and pneumatic methods produced similar estimates of P50, but differed for P12 and P88. All three species were quite vulnerable to embolism, with P50 of -1.9 MPa (C. virgata), -2.3 MPa (C. congesta), and -2.4 MPa (C. parviflora). Estimates of P50, ΨTLP and ΨMD aligned with habitat moisture stress, with highest values found in the semi-riparian C. virgata. Consistent differences in P50, ΨMD and ΨTLP between species resulted in consistent hydraulic safety margins across species of 0.96 ± 0.1 MPa between ΨMD and P50, with onset of embolism occurring 0.43 ± 0.04 MPa after ΨTLP for all three species. Our study demonstrates that restio occupancy of dry environments involves more than the evolution of highly resistant xylem, suggesting that other aspects of water relations are key to understanding trait-environment relationships in this group.
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Affiliation(s)
- A G West
- Department of Biological Sciences, University of Cape Town, Rondebosch, South Africa
| | - K Atkins
- Department of Biological Sciences, University of Cape Town, Rondebosch, South Africa
| | - J J van Blerk
- Department of Biological Sciences, University of Cape Town, Rondebosch, South Africa
| | - R P Skelton
- Fynbos Node, South African Environmental Observation Network, Newlands, South Africa
- Department of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
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2
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Haverroth EJ, Rimer IM, Oliveira LA, de Lima LGA, Cesarino I, Martins SCV, McAdam SAM, Cardoso AA. Gradients in embolism resistance within stems driven by secondary growth in herbs. PLANT, CELL & ENVIRONMENT 2024. [PMID: 38644584 DOI: 10.1111/pce.14921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 03/22/2024] [Accepted: 04/08/2024] [Indexed: 04/23/2024]
Abstract
The stems of some herbaceous species can undergo basal secondary growth, leading to a continuum in the degree of woodiness along the stem. Whether the formation of secondary growth in the stem base results in differences in embolism resistance between the base and the upper portions of stems is unknown. We assessed the embolism resistance of leaves and the basal and upper portions of stems simultaneously within the same individuals of two divergent herbaceous species that undergo secondary growth in the mature stem bases. The species were Solanum lycopersicum (tomato) and Senecio minimus (fireweed). Basal stem in mature plants of both species displayed advanced secondary growth and greater resistance to embolism than the upper stem. This also resulted in significant vulnerability segmentation between the basal stem and the leaves in both species. Greater embolism resistance in the woodier stem base was found alongside decreases in the pith-to-xylem ratio, increases in the proportion of secondary xylem, and increases in lignin content. We show that there can be considerable variation in embolism resistance across the stem in herbs and that this variation is linked to the degree of secondary growth present. A gradient in embolism resistance across the stem in herbaceous plants could be an adaptation to ensure reproduction or basal resprouting during episodes of drought late in the lifecycle.
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Affiliation(s)
- Eduardo J Haverroth
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina, USA
| | - Ian M Rimer
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Leonardo A Oliveira
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina, USA
| | - Leydson G A de Lima
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
- Synthetic and Systems Biology Center, InovaUSP, Avenida Professor Lucio Martins Rodrigues, São Paulo, Brazil
| | - Igor Cesarino
- Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, São Paulo, Brazil
- Synthetic and Systems Biology Center, InovaUSP, Avenida Professor Lucio Martins Rodrigues, São Paulo, Brazil
| | - Samuel C V Martins
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Brazil
| | - Scott A M McAdam
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Amanda A Cardoso
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina, USA
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3
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Grossman JJ, Coe HB, Fey O, Fraser N, Salaam M, Semper C, Williamson CG. Temperate woody species across the angiosperm phylogeny acquire tolerance to water deficit stress during the growing season. THE NEW PHYTOLOGIST 2024. [PMID: 38511237 DOI: 10.1111/nph.19692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 03/03/2024] [Indexed: 03/22/2024]
Abstract
Understanding the capacity of temperate trees to acclimate to limited soil water has become essential in the face of increasing drought risk due to climate change. We documented seasonal - or phenological - patterns in acclimation to water deficit stress in stems and leaves of tree species spanning the angiosperm phylogeny. Over 3 yr of field observations carried out in two US arboreta, we measured stem vulnerability to embolism (36 individuals of 7 Species) and turgor loss point (119 individuals of 27 species) over the growing season. We also conducted a growth chamber experiment on 20 individuals of one species to assess the mechanistic relationship between soil water restriction and acclimation. In three-quarters of species measured, plants became less vulnerable to embolism and/or loss of turgor over the growing season. We were able to stimulate this acclimatory effect by withholding water in the growth chamber experiment. Temperate angiosperms are capable of acclimation to soil water deficit stress, showing maximum vulnerability to soil water deficits following budbreak and becoming more resilient to damage over the course of the growing season or in response to simulated drought. The species-specific tempo and extent of this acclimatory potential constitutes preadaptive climate change resilience.
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Affiliation(s)
- Jake J Grossman
- Biology Department & Environmental Studies Department, St. Olaf College, 1520 St Olaf Ave, Northfield, MN, 55057, USA
| | - Henry B Coe
- Environmental Permitting and Planning Group, Hazen and Sawyer 498 Seventh Ave #11, New York, NY, 10018, USA
| | - Olivia Fey
- Biology Department, Swarthmore College, 500 College Ave, Swarthmore, PA, 19081, USA
| | - Natalie Fraser
- Biology Department, Swarthmore College, 500 College Ave, Swarthmore, PA, 19081, USA
| | - Musa Salaam
- Wilmer Eye Institute, Bayview Medical Center, Johns Hopkins University, 4940 Eastern Ave, Baltimore, MD, 21224, USA
| | - Chelsea Semper
- Department of Forest Resources, University of Minnesota, 115 Green Hall, 1530 Cleveland Ave N, St. Paul, MN, 55108, USA
| | - Ceci G Williamson
- Biology Department, Swarthmore College, 500 College Ave, Swarthmore, PA, 19081, USA
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4
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Mercado-Reyes JA, Pereira TS, Manandhar A, Rimer IM, McAdam SAM. Extreme drought can deactivate ABA biosynthesis in embolism-resistant species. PLANT, CELL & ENVIRONMENT 2024; 47:497-510. [PMID: 37905689 DOI: 10.1111/pce.14754] [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: 03/25/2022] [Revised: 08/24/2023] [Accepted: 10/18/2023] [Indexed: 11/02/2023]
Abstract
The phytohormone abscisic acid (ABA) is synthesised by plants during drought to close stomata and regulate desiccation tolerance pathways. Conifers and some angiosperms with embolism-resistant xylem show a peaking-type (p-type) response in ABA levels, in which ABA levels increase early in drought then decrease as drought progresses, declining to pre-stressed levels. The mechanism behind this dynamic remains unknown. Here, we sought to characterise the mechanism driving p-type ABA dynamics in the conifer Callitris rhomboidea and the highly drought-resistant angiosperm Umbellularia californica. We measured leaf water potentials (Ψl ), stomatal conductance, ABA, conjugates and phaseic acid (PA) levels in potted plants during a prolonged but non-fatal drought. Both species displayed a p-type ABA dynamic during prolonged drought. In branches collected before and after the peak in endogenous ABA levels in planta, that were rehydrated overnight and then bench dried, ABA biosynthesis was deactivated beyond leaf turgor loss point. Considerable conversion of ABA to conjugates was found to occur during drought, but not catabolism to PA. The mechanism driving the decline in ABA levels in p-type species may be conserved across embolism-resistant seed plants and is mediated by sustained conjugation of ABA and the deactivation of ABA accumulation as Ψl becomes more negative than turgor loss.
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Affiliation(s)
- Joel A Mercado-Reyes
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Talitha Soares Pereira
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Anju Manandhar
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Ian M Rimer
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Scott A M McAdam
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
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5
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Roth-Nebelsick A, Konrad W. Modeling and Analyzing Xylem Vulnerability to Embolism as an Epidemic Process. Methods Mol Biol 2024; 2722:17-34. [PMID: 37897597 DOI: 10.1007/978-1-0716-3477-6_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/30/2023]
Abstract
Xylem vulnerability to embolism can be quantified by "vulnerability curves" (VC) that are obtained by subjecting wood samples to increasingly negative water potential and monitoring the progressive loss of hydraulic conductivity. VC are typically sigmoidal, and various approaches are used to fit the experimentally obtained VC data for extracting benchmark data of vulnerability to embolism. In addition to such empirical methods, mechanistic approaches to calculate embolism propagation are epidemic modeling and network theory. Both describe the transmission of "objects" (in this case, the transmission of gas) between interconnected elements. In network theory, a population of interconnected elements is described by graphs in which objects are represented by vertices or nodes and connections between these objections as edges linking the vertices. A graph showing a population of interconnected xylem conduits represents an "individual" wood sample that allows spatial tracking of embolism propagation. In contrast, in epidemic modeling, the transmission dynamics for a population that is subdivided into infection-relevant groups is calculated by an equation system. For this, embolized conduits are considered to be "infected," and the "infection" is the transmission of gas from embolized conduits to their still water-filled neighbors. Both approaches allow for a mechanistic simulation of embolism propagation.
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Affiliation(s)
| | - Wilfried Konrad
- Department of Geosciences, University of Tübingen, Tübingen, Germany.
- Institute of Botany, Technical University of Dresden, Dresden, Germany.
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Zhang XM, Xia Y, Li JT, Shi XQ, Liu LX, Tang M, Tang J, Sun W, Wen ZR, Yi Y. Assessing inter-intraspecific variability of leaf vulnerability to embolism for 10 alpine Rhododendron species growing in Southwestern China. PHYSIOLOGIA PLANTARUM 2024; 176:e14211. [PMID: 38351399 DOI: 10.1111/ppl.14211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 01/18/2024] [Accepted: 01/28/2024] [Indexed: 02/16/2024]
Abstract
Alpine Rhododendron species are prominent constituents and renowned ornamental plants in alpine ecosystems. Consequently, evaluating the genetic variation in embolism resistance within the genus Rhododendron and predicting their adaptability to future climate change is important. Nevertheless, the assessment of embolism resistance in Rhododendron species remains limited. This investigation aimed to examine leaf vulnerability to embolism across ten alpine Rhododendron species, which are frequently employed as ornamental species in Rhododendron forests in Southwest China. The study analyzed the correlation between embolism resistance and various morphological traits, while also conducting water control experiments to evaluate the relationship between embolism resistance and drought resistance. The outcomes indicated pronounced variations in leaf vulnerability to embolism among species, as reflected by the water potential at 50% of embolized pixels (P50 ). Furthermore, the leaf P50 exhibited a significant positive correlation with vessel diameter (D) (R2 = 0.44, P = 0.03) and vessel wall span (b) (R2 = 0.64, P = 0.005), while displaying a significant negative correlation with vessel reinforcement ((t/b)2 ) (R2 = 0.67, P = 0.004). These findings underscore the reliability of selecting species based on embolism vulnerability to preserve the diversity of alpine ecosystems and foster resilience to climate change.
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Affiliation(s)
- Xi-Min Zhang
- Key Laboratory of Plant Physiology and Development Regulation, Guizhou Normal University, Guiyang, China
- Key Laboratory of Environment Friendly Management on Alpine Rhododendron Diseases and Pests of Institutions of Higher Learning in Guizhou Province, Guizhou Normal University, Guiyang, China
- School of Life Sciences, Guizhou Normal University, Guiyang, China
| | - Ying Xia
- Key Laboratory of State Forestry Administration on Biodiversity Conservation in Karst Area of Southwest, Guizhou Normal University, Guiyang, China
- School of Life Sciences, Guizhou Normal University, Guiyang, China
| | - Jie-Ting Li
- Key Laboratory of Plant Physiology and Development Regulation, Guizhou Normal University, Guiyang, China
- School of Life Sciences, Guizhou Normal University, Guiyang, China
| | - Xiao-Qian Shi
- Key Laboratory of Plant Physiology and Development Regulation, Guizhou Normal University, Guiyang, China
- School of Life Sciences, Guizhou Normal University, Guiyang, China
| | - Lun-Xian Liu
- Key Laboratory of Plant Physiology and Development Regulation, Guizhou Normal University, Guiyang, China
- School of Life Sciences, Guizhou Normal University, Guiyang, China
| | - Ming Tang
- Key Laboratory of State Forestry Administration on Biodiversity Conservation in Karst Area of Southwest, Guizhou Normal University, Guiyang, China
- School of Life Sciences, Guizhou Normal University, Guiyang, China
| | - Jing Tang
- Key Laboratory of Plant Physiology and Development Regulation, Guizhou Normal University, Guiyang, China
- School of Life Sciences, Guizhou Normal University, Guiyang, China
| | - Wei Sun
- Key Laboratory of Plant Physiology and Development Regulation, Guizhou Normal University, Guiyang, China
- School of Life Sciences, Guizhou Normal University, Guiyang, China
| | - Zhi-Rui Wen
- Key Laboratory of Plant Physiology and Development Regulation, Guizhou Normal University, Guiyang, China
- Key Laboratory of State Forestry Administration on Biodiversity Conservation in Karst Area of Southwest, Guizhou Normal University, Guiyang, China
| | - Yin Yi
- Key Laboratory of Plant Physiology and Development Regulation, Guizhou Normal University, Guiyang, China
- Key Laboratory of State Forestry Administration on Biodiversity Conservation in Karst Area of Southwest, Guizhou Normal University, Guiyang, China
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7
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West AG, Bloy ST, Skelton RP, Midgley JJ. Hydraulic segmentation explains differences in loss of branch conductance caused by fire. TREE PHYSIOLOGY 2023; 43:2121-2130. [PMID: 37672220 PMCID: PMC10714316 DOI: 10.1093/treephys/tpad108] [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: 11/11/2022] [Revised: 08/28/2023] [Accepted: 09/03/2023] [Indexed: 09/07/2023]
Abstract
The hydraulic death hypothesis suggests that fires kill trees by damaging the plant's hydraulic continuum in addition to stem cambium. A corollary to this hypothesis is that plants that survive fires possess 'pyrohydraulic' traits that prevent heat-induced embolism formation in the xylem and aid post-fire survival. We examine whether hydraulic segmentation within stem xylem may act as such a trait. To do so, we measured the percentage loss of conductance (PLC) and vulnerability to embolism axially along segments of branches exposed to heat plumes in two differing species, fire-tolerant Eucalyptus cladocalyx F. Muell and fire-sensitive Kiggelaria africana L., testing model predictions that fire-tolerant species would exhibit higher degrees of hydraulic segmentation (greater PLC in the distal parts of the branch than the basal) than fire-intolerant species (similar PLC between segments). Following exposure to a heat plume, K. africana suffered between 73 and 84% loss of conductance in all branch segments, whereas E. cladocalyx had 73% loss of conductance in whole branches, including the distal tips, falling to 29% in the most basal part of the branch. There was no evidence for differences in resistance segmentation between the species, and there was limited evidence for differences in distal vulnerability to embolism across the branches. Hydraulic segmentation in E. cladocalyx may enable it to resprout effectively post-fire with a functional hydraulic system. The lack of hydraulic segmentation in K. africana reveals the need to understand possible trade-offs associated with hydraulic segmentation in long-lived woody species with respect to drought and fire.
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Affiliation(s)
- Adam G West
- Department of Biological Sciences, University Avenue, University of Cape Town, 7701, Cape Town, South Africa
| | - Shonese T Bloy
- Department of Biological Sciences, University Avenue, University of Cape Town, 7701, Cape Town, South Africa
| | - Robert P Skelton
- SAEON Fynbos Node, Centre for Biodiversity Conservation, Kirstenbosch Gardens, 7708, Cape Town, South Africa
- Animal, Plant and Environmental Sciences, University of the Witwatersrand, 1 Jan Smuts Ave, Braamfontein, 2001, Johannesburg, South Africa
| | - Jeremy J Midgley
- Department of Biological Sciences, University Avenue, University of Cape Town, 7701, Cape Town, South Africa
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8
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Paligi SS, Link RM, Isasa E, Bittencourt P, Cabral JS, Jansen S, Oliveira RS, Pereira L, Schuldt B. Assessing the agreement between the pneumatic and the flow-centrifuge method for estimating xylem safety in temperate diffuse-porous tree species. PLANT BIOLOGY (STUTTGART, GERMANY) 2023; 25:1171-1185. [PMID: 37703535 DOI: 10.1111/plb.13573] [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: 03/16/2023] [Accepted: 07/06/2023] [Indexed: 09/15/2023]
Abstract
The increasing frequency of global change-type droughts has created a need for fast, accurate and widely applicable techniques for estimating xylem embolism resistance to improve forecasts of future forest changes. We used data from 12 diffuse-porous temperate tree species covering a wide range of xylem safety to compare the pneumatic and flow-centrifuge method, two rapid methods used for constructing xylem vulnerability curves. We evaluated the agreement between parameters estimated with both methods and the sensitivity of pneumatic measurements to the duration of air discharge (AD) measurements. There was close agreement between xylem water potentials at 50% air discharged (PAD), estimated with the Pneumatron, and 50% loss of hydraulic conductivity (PLC), estimated with the flow-centrifuge method (mean signed deviation: 0.12 MPa, Pearson correlation: 0.96 after 15 s of gas extraction). However, the relationship between the estimated slopes was more variable, resulting in lower agreement in the xylem water potential at 12% and 88% PAD/PLC. The agreement between the two methods was not affected by species-specific vessel length distributions. All pneumatic parameters were sensitive to AD time. Overall agreement was highest at relatively short AD times, with an optimum at 16 s. Our results highlight the value of the Pneumatron as an easy and reliable tool to estimate 50% embolism thresholds for a wide range of diffuse-porous temperate angiosperms. Further, our study provides a set of useful metrics for methodological comparisons of vulnerability curves in terms of systematic and random deviations, as well as overall agreement.
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Affiliation(s)
- S S Paligi
- Chair of Ecophysiology and Vegetation Ecology, Julius-von-Sachs Institute of Biological Sciences, University of Würzburg, Würzburg, Germany
| | - R M Link
- Chair of Ecophysiology and Vegetation Ecology, Julius-von-Sachs Institute of Biological Sciences, University of Würzburg, Würzburg, Germany
- Chair of Forest Botany, Institute of Forest Botany and Forest Zoology, Technische Universität Dresden, Tharandt, Germany
| | - E Isasa
- Chair of Ecophysiology and Vegetation Ecology, Julius-von-Sachs Institute of Biological Sciences, University of Würzburg, Würzburg, Germany
| | - P Bittencourt
- College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - J S Cabral
- Ecosystem Modeling Group, Center for Computational and Theoretical Biology, University of Würzburg, Würzburg, Germany
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, UK
| | - S Jansen
- Institute of Botany, Ulm University, Ulm, Germany
| | - R S Oliveira
- Department of Plant Biology, Instituto de Biologia, University of Campinas, Campinas, SP, Brazil
| | - L Pereira
- Institute of Botany, Ulm University, Ulm, Germany
| | - B Schuldt
- Chair of Ecophysiology and Vegetation Ecology, Julius-von-Sachs Institute of Biological Sciences, University of Würzburg, Würzburg, Germany
- Chair of Forest Botany, Institute of Forest Botany and Forest Zoology, Technische Universität Dresden, Tharandt, Germany
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9
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Carins-Murphy MR, Cochard H, Deans RM, Gracie AJ, Brodribb TJ. Combined heat and water stress leads to local xylem failure and tissue damage in pyrethrum flowers. PLANT PHYSIOLOGY 2023; 193:356-370. [PMID: 37325893 PMCID: PMC10469517 DOI: 10.1093/plphys/kiad349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 05/25/2023] [Accepted: 05/27/2023] [Indexed: 06/17/2023]
Abstract
Flowers are critical for angiosperm reproduction and the production of food, fiber, and pharmaceuticals, yet for unknown reasons, they appear particularly sensitive to combined heat and drought stress. A possible explanation for this may be the co-occurrence of leaky cuticles in flower petals and a vascular system that has a low capacity to supply water and is prone to failure under water stress. These characteristics may render reproductive structures more susceptible than leaves to runaway cavitation-an uncontrolled feedback cycle between rising water stress and declining water transport efficiency that can rapidly lead to lethal tissue desiccation. We provide modeling and empirical evidence to demonstrate that flower damage in the perennial crop pyrethrum (Tanacetum cinerariifolium), in the form of irreversible desiccation, corresponds with runaway cavitation in the flowering stem after a combination of heat and water stress. We show that tissue damage is linked to greater evaporative demand during high temperatures rather than direct thermal stress. High floral transpiration dramatically reduced the soil water deficit at which runaway cavitation was triggered in pyrethrum flowering stems. Identifying runaway cavitation as a mechanism leading to heat damage and reproductive losses in pyrethrum provides different avenues for process-based modeling to understand the impact of climate change on cultivated and natural plant systems. This framework allows future investigation of the relative susceptibility of diverse plant species to reproductive failure under hot and dry conditions.
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Affiliation(s)
- Madeline R Carins-Murphy
- School of Natural Sciences, Discipline of Biological Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Hervé Cochard
- INRAE, PIAF, Université Clermont-Auvergne, Clermont-Ferrand 63000, France
| | - Ross M Deans
- Department of Viticulture & Enology, University of California, Davis, California 95616, USA
| | - Alistair J Gracie
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Timothy J Brodribb
- School of Natural Sciences, Discipline of Biological Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia
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10
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Feng F, Wagner Y, Klein T, Hochberg U. Xylem resistance to cavitation increases during summer in Pinus halepensis. PLANT, CELL & ENVIRONMENT 2023; 46:1849-1859. [PMID: 36793149 DOI: 10.1111/pce.14573] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 02/08/2023] [Accepted: 02/14/2023] [Indexed: 05/04/2023]
Abstract
Cavitation resistance has often been viewed as a relatively static trait, especially for stems of forest trees. Meanwhile, other hydraulic traits, such as turgor loss point (Ψtlp ) and xylem anatomy, change during the season. In this study, we hypothesized that cavitation resistance is also dynamic, changing in coordination with Ψtlp . We began with a comparison of optical vulnerability (OV), microcomputed tomography (µCT) and cavitron methods. All three methods significantly differed in the slope of the curve,Ψ12 and Ψ88 , but not in Ψ50 (xylem pressures that cause 12%, 88%, 50% cavitation, respectively). Thus, we followed the seasonal dynamics (across 2 years) of Ψ50 in Pinus halepensis under Mediterranean climate using the OV method. We found that Ψ50 is a plastic trait with a reduction of approximately 1 MPa from the end of the wet season to the end of the dry season, in coordination with the dynamics of the midday xylem water potential (Ψmidday ) and the Ψtlp . The observed plasticity enabled the trees to maintain a stable positive hydraulic safety margin and avoid cavitation during the long dry season. Seasonal plasticity is vital for understanding the actual risk of cavitation to plants and for modeling species' ability to tolerate harsh environments.
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Affiliation(s)
- Feng Feng
- Institute of Soil, Water and Environmental Sciences, Volcani Center, Agricultural Research Organization, Rishon LeZion, Israel
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Yael Wagner
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Tamir Klein
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Uri Hochberg
- Institute of Soil, Water and Environmental Sciences, Volcani Center, Agricultural Research Organization, Rishon LeZion, Israel
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11
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Johnson KM, Brodribb TJ. Evidence for a trade-off between growth rate and xylem cavitation resistance in Callitris rhomboidea. TREE PHYSIOLOGY 2023:tpad037. [PMID: 36947141 DOI: 10.1093/treephys/tpad037] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 03/14/2023] [Indexed: 06/18/2023]
Abstract
The ideal plant water transport system is one that features high efficiency and resistance to drought-induced damage (xylem cavitation), however species rarely possess both. This may be explained by trade-offs between traits, yet thus far, no proposed trade-off has offered a universal explanation for the lack water transport systems that are both highly drought-resistant and highly efficient. Here we find evidence for a new trade-off, between growth rate and resistance to xylem cavitation, in the canopies of a drought-resistant tree species (Callitris rhomboidea). Wide variation in cavitation resistance (P50) was found in distal branch tips (< 2 mm in diameter), converging to low variation in P50 in larger diameter stems (> 2 mm). We found a significant correlation between cavitation resistance and distal branchlet internode length across branch tips in C. rhomboidea canopies. Branchlets with long internodes (8 mm or longer) were significantly more vulnerable to drought-induced xylem cavitation than shorter internodes (4 mm or shorter). This suggests that varying growth rates, leading to differences in internode length, drive differences in cavitation resistance in C. rhomboidea trees. The only distinct anatomical difference found between internodes was the pith size, with the average pith to xylem area in long internodes, 5x greater than in short internodes. Understanding whether this trade-off exists within and between species will help us to uncover what drives and limits drought resistance across the world's flora.
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12
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Tonet V, Carins-Murphy M, Deans R, Brodribb TJ. Deadly acceleration in dehydration of Eucalyptus viminalis leaves coincides with high-order vein cavitation. PLANT PHYSIOLOGY 2023; 191:1648-1661. [PMID: 36690460 PMCID: PMC10022613 DOI: 10.1093/plphys/kiad016] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 12/08/2022] [Accepted: 12/17/2022] [Indexed: 05/17/2023]
Abstract
Xylem cavitation during drought is proposed as a major driver of canopy collapse, but the mechanistic link between hydraulic failure and leaf damage in trees is still uncertain. Here, we used the tree species manna gum (Eucalyptus viminalis) to explore the connection between xylem dysfunction and lethal desiccation in leaves. Cavitation damage to leaf xylem could theoretically trigger lethal desiccation of tissues by severing water supply under scenarios such as runaway xylem cavitation, or the local failure of terminal parts of the leaf vein network. To investigate the role of xylem failure in leaf death, we compared the timing of damage to the photosynthetic machinery (Fv/Fm decline) with changes in plant hydration and xylem cavitation during imposed water stress. The water potential at which Fv/Fm was observed to decline corresponded to the water potential marking a transition from slow to very rapid tissue dehydration. Both events also occurred simultaneously with the initiation of cavitation in leaf high-order veins (HOV, veins from the third order above) and the analytically derived point of leaf runaway hydraulic failure. The close synchrony between xylem dysfunction and the photosynthetic damage strongly points to water supply disruption as the trigger for desiccation of leaves in this hardy evergreen tree. These results indicate that runaway cavitation, possibly triggered by HOV network failure, is the tipping agent determining the vulnerability of E. viminalis leaves to damage during drought and suggest that HOV cavitation and runaway hydraulic failure may play a general role in determining canopy damage in plants.
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Affiliation(s)
- Vanessa Tonet
- School of Biological Sciences, University of Tasmania, Sandy Bay, Tasmania 7001, Australia
| | - Madeline Carins-Murphy
- School of Biological Sciences, University of Tasmania, Sandy Bay, Tasmania 7001, Australia
| | - Ross Deans
- ARC Centre of Excellence in Translational Photosynthesis, Division of Plant Science, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
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13
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Zheng C, Bochmann H, Liu Z, Kant J, Schrey SD, Wojciechowski T, Postma JA. Plant root plasticity during drought and recovery: What do we know and where to go? FRONTIERS IN PLANT SCIENCE 2023; 14:1084355. [PMID: 37008469 PMCID: PMC10061088 DOI: 10.3389/fpls.2023.1084355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 02/28/2023] [Indexed: 06/19/2023]
Abstract
AIMS Drought stress is one of the most limiting factors for agriculture and ecosystem productivity. Climate change exacerbates this threat by inducing increasingly intense and frequent drought events. Root plasticity during both drought and post-drought recovery is regarded as fundamental to understanding plant climate resilience and maximizing production. We mapped the different research areas and trends that focus on the role of roots in plant response to drought and rewatering and asked if important topics were overlooked. METHODS We performed a comprehensive bibliometric analysis based on journal articles indexed in the Web of Science platform from 1900-2022. We evaluated a) research areas and temporal evolution of keyword frequencies, b) temporal evolution and scientific mapping of the outputs over time, c) trends in the research topics analysis, d) marked journals and citation analysis, and e) competitive countries and dominant institutions to understand the temporal trends of root plasticity during both drought and recovery in the past 120 years. RESULTS Plant physiological factors, especially in the aboveground part (such as "photosynthesis", "gas-exchange", "abscisic-acid") in model plants Arabidopsis, crops such as wheat and maize, and trees were found to be the most popular study areas; they were also combined with other abiotic factors such as salinity, nitrogen, and climate change, while dynamic root growth and root system architecture responses received less attention. Co-occurrence network analysis showed that three clusters were classified for the keywords including 1) photosynthesis response; 2) physiological traits tolerance (e.g. abscisic acid); 3) root hydraulic transport. Thematically, themes evolved from classical agricultural and ecological research via molecular physiology to root plasticity during drought and recovery. The most productive (number of publications) and cited countries and institutions were situated on drylands in the USA, China, and Australia. In the past decades, scientists approached the topic mostly from a soil-plant hydraulic perspective and strongly focused on aboveground physiological regulation, whereas the actual belowground processes seemed to have been the elephant in the room. There is a strong need for better investigation into root and rhizosphere traits during drought and recovery using novel root phenotyping methods and mathematical modeling.
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Affiliation(s)
- Congcong Zheng
- Institute of Bio- and Geosciences – Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, Jülich, Germany
- Faculty of Agriculture, University of Bonn, Bonn, Germany
| | - Helena Bochmann
- Institute of Bio- and Geosciences – Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, Jülich, Germany
- Faculty of Agriculture, University of Bonn, Bonn, Germany
| | - Zhaogang Liu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
| | - Josefine Kant
- Institute of Bio- and Geosciences – Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Silvia D. Schrey
- Institute of Bio- and Geosciences – Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Tobias Wojciechowski
- Institute of Bio- and Geosciences – Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Johannes Auke Postma
- Institute of Bio- and Geosciences – Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, Jülich, Germany
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14
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Skelton RP, West AG, Buttner D, Dawson TE. Consistent responses to moisture stress despite diverse growth forms within mountain fynbos communities. Oecologia 2023; 201:323-339. [PMID: 36692692 PMCID: PMC9944370 DOI: 10.1007/s00442-023-05326-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Accepted: 01/17/2023] [Indexed: 01/25/2023]
Abstract
Understanding climate change impacts on the Cape Floristic Region requires improved knowledge of plant physiological responses to the environment. Studies examining physiological responses of mountain fynbos have consisted of campaign-based measurements, capturing snapshots of plant water relations and photosynthesis. We examine conclusions drawn from prior studies by tracking in situ physiological responses of three species, representing dominant growth forms (proteoid, ericoid, restioid), over 2 years using miniature continuous sap flow technology, long-term observations of leaf/culm water potential and gas exchange, and xylem vulnerability to embolism. We observed considerable inter-specific variation in the timing and extent of seasonal declines in productivity. Shallow-rooted Erica monsoniana exhibited steep within-season declines in sap flow and water potentials, and pronounced inter-annual variability in total daily sap flux (Js). Protea repens showed steady reductions in Js across both years, despite deeper roots and less negative water potentials. Cannomois congesta-a shallow-rooted restioid-was least negatively impacted. Following rehydrating rain at the end of summer, gas exchange recovery was lower in the drier year compared with the normal year, but did not differ between species. Loss of function in the drier year was partially accounted for by loss of xylem transport capacity in Erica and Cannomois, but not Protea. Hitherto unseen water use patterns, including inter-annual variability of gas exchange associated with contrasting water uptake properties, reveal that species use different mechanisms to cope with summer dry periods. Revealing physiological responses of key growth forms enhances predictions of plant function within mountain fynbos under future conditions.
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Affiliation(s)
| | - Adam G West
- Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
| | - Daniel Buttner
- Department of Botany, Nelson Mandela University, Gqeberha, South Africa
| | - Todd E Dawson
- Department of Integrative Biology, University of California, Berkeley, Berkeley, USA
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15
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Mantova M, Cochard H, Burlett R, Delzon S, King A, Rodriguez-Dominguez CM, Ahmed MA, Trueba S, Torres-Ruiz JM. On the path from xylem hydraulic failure to downstream cell death. THE NEW PHYTOLOGIST 2023; 237:793-806. [PMID: 36305207 DOI: 10.1111/nph.18578] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 10/17/2022] [Indexed: 06/16/2023]
Abstract
Xylem hydraulic failure (HF) has been identified as a ubiquitous factor in triggering drought-induced tree mortality through the damage induced by the progressive dehydration of plant living cells. However, fundamental evidence of the mechanistic link connecting xylem HF to cell death has not been identified yet. The main aim of this study was to evaluate, at the leaf level, the relationship between loss of hydraulic function due to cavitation and cell death under drought conditions and discern how this relationship varied across species with contrasting resistances to cavitation. Drought was induced by withholding water from potted seedlings, and their leaves were sampled to measure their relative water content (RWC) and cell mortality. Vulnerability curves to cavitation at the leaf level were constructed for each species. An increment in cavitation events occurrence precedes the onset of cell mortality. A variation in cells tolerance to dehydration was observed along with the resistance to cavitation. Overall, our results indicate that the onset of cellular mortality occurs at lower RWC than the one for cavitation indicating the role of cavitation in triggering cellular death. They also evidenced a critical RWC for cellular death varying across species with different cavitation resistance.
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Affiliation(s)
- Marylou Mantova
- Université Clermont Auvergne, INRAE, PIAF, 63000, Clermont-Ferrand, France
| | - Hervé Cochard
- Université Clermont Auvergne, INRAE, PIAF, 63000, Clermont-Ferrand, France
| | - Régis Burlett
- Université Bordeaux, INRAE, BIOGECO, 33615, Pessac, France
| | - Sylvain Delzon
- Université Bordeaux, INRAE, BIOGECO, 33615, Pessac, France
| | - Andrew King
- Synchrotron SOLEIL, L'Orme des Merisiers, 91190, Gif-sur-Yvette cedex, France
| | - Celia M Rodriguez-Dominguez
- Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiologia de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes, 10, 41012, Sevilla, Spain
| | - Mutez A Ahmed
- Chair of Soil Physics, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, 95440, Bayreuth, Germany
- Department of Land, Air and Water Resources, University of California Davis, Davis, CA, 95616, USA
| | | | - José M Torres-Ruiz
- Université Clermont Auvergne, INRAE, PIAF, 63000, Clermont-Ferrand, France
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16
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Avila RT, Kane CN, Batz TA, Trabi C, Damatta FM, Jansen S, McAdam SAM. The relative area of vessels in xylem correlates with stem embolism resistance within and between genera. TREE PHYSIOLOGY 2023; 43:75-87. [PMID: 36070431 DOI: 10.1093/treephys/tpac110] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/30/2022] [Indexed: 06/15/2023]
Abstract
The resistance of xylem conduits to embolism is a major factor defining drought tolerance and can set the distributional limits of species across rainfall gradients. Recent work suggests that the proximity of vessels to neighbors increases the vulnerability of a conduit. We therefore investigated whether the relative vessel area of xylem correlates with intra- and inter-generic variation in xylem embolism resistance in species pairs or triplets from the genera Acer, Cinnamomum, Ilex, Quercus and Persea, adapted to environments differing in aridity. We used the optical vulnerability method to assess embolism resistance in stems and conducted anatomical measurements on the xylem in which embolism resistance was quantified. Vessel lumen fraction (VLF) correlated with xylem embolism resistance across and within genera. A low VLF likely increases the resistance to gas movement between conduits, by diffusion or advection, whereas a high VLF enhances gas transport thorough increased conduit-to-conduit connectivity and reduced distances between conduits and therefore the likelihood of embolism propagation. We suggest that the rate of gas movement due to local pressure differences and xylem network connectivity is a central driver of embolism propagation in angiosperm vessels.
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Affiliation(s)
- Rodrigo T Avila
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36570-900, Brazil
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
| | - Cade N Kane
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
| | - Timothy A Batz
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
| | - Christophe Trabi
- Faculty of Natural Sciences, Institute of Systematic Botany and Ecology, Ulm University, Ulm, Baden-Württemberg 89081, Germany
| | - Fábio M Damatta
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36570-900, Brazil
| | - Steven Jansen
- Faculty of Natural Sciences, Institute of Systematic Botany and Ecology, Ulm University, Ulm, Baden-Württemberg 89081, Germany
| | - Scott A M McAdam
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA
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17
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Xu T, Li Z, Bao S, Su Y, Su Z, Zhi S, Zheng E. Xylem vessel type and structure influence the water transport characteristics of Panax notoginseng. PLoS One 2023; 18:e0281080. [PMID: 36877678 PMCID: PMC9987790 DOI: 10.1371/journal.pone.0281080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 01/15/2023] [Indexed: 03/07/2023] Open
Abstract
Panax notoginseng plays a very important role in medicinal and economic value. The restriction imposed by the hydraulic pathway is considered to be the main limitation on the optimal growth state of Panax notoginseng. The flow resistance and water transport efficiency of vessel were affected by vessel type and secondary thickening structure. The vessel structure parameters of Panax notoginseng were obtained by experimental anatomy, and the flow resistance characteristics were analyzed by numerical simulation. The results showed that the xylem vessels had annular thickening and pit thickening walls. The flow resistance coefficient (ξ) of the pitted thickening vessel was significantly lower than that of annular thickening vessel in four cross-sectional types. The ξ of the circular cross-sectional vessel was the largest, followed by the hexagon, pentagon cross-sectional vessel and the lowest was the quadrilateral cross-sectional vessel, and the structure coefficient (S) was just the opposite. The ξ of the vessel model was positively correlated with the annular height, pitted width and pitted height, and negatively correlated with the annular inscribed circle diameter, annular width, annular spacing, pitted inscribed circle diameter and pitted spacing. Among them, annular (pitted) height and the annular (pitted) inscribed circle diameter had a great influence on the ξ. The increasing and decreasing trend of the S and ξ were opposite in the change of annular (pitted) inscribed circle diameter, and consistent in the change of in other structural parameters, indicating that the secondary wall thickening structure limited the inner diameter of the vessel to maintain a balance between flow resistance and transport efficiency.
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Affiliation(s)
- Tianyu Xu
- School of Hydraulic and Electric Power, Heilongjiang University, Harbin, China
| | - Zonglei Li
- School of Hydraulic and Electric Power, Heilongjiang University, Harbin, China
| | - Sanlin Bao
- School of Hydraulic and Electric Power, Heilongjiang University, Harbin, China
| | - Yanru Su
- School of Hydraulic and Electric Power, Heilongjiang University, Harbin, China
| | - Zhouming Su
- School of Hydraulic and Electric Power, Heilongjiang University, Harbin, China
| | - Shuteng Zhi
- School of Hydraulic and Electric Power, Heilongjiang University, Harbin, China
| | - Ennan Zheng
- School of Hydraulic and Electric Power, Heilongjiang University, Harbin, China
- * E-mail:
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18
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Brum M, Pereira L, Ribeiro RV, Jansen S, Bittencourt PRL, Oliveira RS, Saleska SR. Reconciling discrepancies in measurements of vulnerability to xylem embolism with the pneumatic method: A comment on Chen et al. (2021) 'Quantifying vulnerability to embolism in tropical trees and lianas using five methods: can discrepancies be explained by xylem structural traits?': A comment on Chen et al. (2021) 'Quantifying vulnerability to embolism in tropical trees and lianas using five methods: can discrepancies be explained by xylem structural traits?'. THE NEW PHYTOLOGIST 2023; 237:374-383. [PMID: 36537303 DOI: 10.1111/nph.18531] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 08/11/2022] [Indexed: 05/12/2023]
Affiliation(s)
- Mauro Brum
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, USA
| | - Luciano Pereira
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Rafael Vasconcelos Ribeiro
- Laboratory of Crop Physiology, Department of Plant Biology, Institute of Biology, University of Campinas (UNICAMP), PO Box 6109, 13083-970, Campinas, SP, Brazil
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Paulo R L Bittencourt
- College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4RJ, UK
| | - Rafael S Oliveira
- Department of Plant Biology, Institute of Biology, UNICAMP, PO Box 6109, 13083-970, Campinas, SP, Brazil
| | - Scott R Saleska
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, USA
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19
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Guan X, Werner J, Cao KF, Pereira L, Kaack L, McAdam SAM, Jansen S. Stem and leaf xylem of angiosperm trees experiences minimal embolism in temperate forests during two consecutive summers with moderate drought. PLANT BIOLOGY (STUTTGART, GERMANY) 2022; 24:1208-1223. [PMID: 34990084 DOI: 10.1111/plb.13384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 12/02/2021] [Indexed: 06/14/2023]
Abstract
Drought events may increase the likelihood that the plant water transport system becomes interrupted by embolism. Yet our knowledge about the temporal frequency of xylem embolism in the field is frequently lacking, as it requires detailed, long-term measurements. We measured xylem embolism resistance and midday xylem water potentials during the consecutive summers of 2019 and 2020 to estimate maximum levels of embolism in leaf and stem xylem of ten temperate angiosperm tree species. We also studied vessel and pit membrane characteristics based on light and electron microscopy to corroborate potential differences in embolism resistance between leaves and stems. Apart from A. pseudoplatanus and Q. petraea, eight species experienced minimum xylem water potentials that were close to or below those required to initiate embolism. Water potentials corresponding to ca. 12% loss of hydraulic conductivity (PLC) could occur in six species, while considerable levels of embolism around 50% PLC were limited to B. pendula and C. avellana. There was a general agreement in embolism resistance between stems and leaves, with leaves being equally or more resistant than stems. Also, xylem embolism resistance was significantly correlated to intervessel pit membrane thickness (TPM ) for stems, but not to vessel diameter and total intervessel pit membrane surface area of a vessel. Our data indicate that low amounts of embolism occur in most species during moderate summer drought, and that considerable levels of embolism are uncommon. Moreover, our experimental and TPM data show that leaf xylem is generally no more vulnerable than stem xylem.
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Affiliation(s)
- X Guan
- Institute of Systematic Botany and Ecology, Ulm University, Ulm, Germany
| | - J Werner
- Institute of Systematic Botany and Ecology, Ulm University, Ulm, Germany
| | - K-F Cao
- Plant Ecophysiology and Evolution Group, State Key Laboratory for Conservation and Utilisation of Subtropical Agro-Bioresources, Guangxi University, Nanning, Guangxi, China
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, China
| | - L Pereira
- Institute of Systematic Botany and Ecology, Ulm University, Ulm, Germany
| | - L Kaack
- Institute of Systematic Botany and Ecology, Ulm University, Ulm, Germany
| | - S A M McAdam
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
| | - S Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Ulm, Germany
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20
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Jiang (蒋国凤) GF, Li (李溯源) SY, Li (李艺蝉) YC, Roddy AB. Coordination of hydraulic thresholds across roots, stems, and leaves of two co-occurring mangrove species. PLANT PHYSIOLOGY 2022; 189:2159-2174. [PMID: 35640109 PMCID: PMC9342987 DOI: 10.1093/plphys/kiac240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 05/09/2022] [Indexed: 05/30/2023]
Abstract
Mangroves are frequently inundated with saline water and have evolved different anatomical and physiological mechanisms to filter and, in some species, excrete excess salt from the water they take up. Because salts impose osmotic stress, interspecific differences in salt tolerance and salt management strategy may influence physiological responses to drought throughout the entire plant hydraulic pathway, from roots to leaves. Here, we characterized embolism vulnerability simultaneously in leaves, stems, and roots of seedlings of two mangrove species (Avicennia marina and Bruguiera gymnorrhiza) along with turgor-loss points in roots and leaves and xylem anatomical traits. In both species, the water potentials causing 50% of total embolism were less negative in roots and leaves than they were in stems, but the water potentials causing incipient embolism (5%) were similar in roots, stems, and leaves. Stomatal closure in leaves and turgor loss in both leaves and roots occurred at water potentials only slightly less negative than the water potentials causing 5% of total embolism. Xylem anatomical traits were unrelated to vulnerability to embolism. Vulnerability segmentation may be important in limiting embolism spread into stems from more vulnerable roots and leaves. Interspecific differences in salt tolerance affected hydraulic traits from roots to leaves: the salt-secretor A. marina lost turgor at more negative water potentials and had more embolism-resistant xylem than the salt-excluder B. gymnorrhiza. Characterizing physiological thresholds of roots may help to explain recent mangrove mortality after drought and extended saltwater inundation.
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Affiliation(s)
| | - Su-Yuan Li (李溯源)
- Guangxi Key Laboratory of Forest Ecology and Conservation, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Nanning 530004, China
| | - Yi-Chan Li (李艺蝉)
- Guangxi Key Laboratory of Forest Ecology and Conservation, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Nanning 530004, China
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21
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Cardoso AA, Kane CN, Rimer IM, McAdam SAM. Seeing is believing: what visualising bubbles in the xylem has revealed about plant hydraulic function. FUNCTIONAL PLANT BIOLOGY : FPB 2022; 49:759-772. [PMID: 35718950 DOI: 10.1071/fp21326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 05/29/2022] [Indexed: 06/15/2023]
Abstract
Maintaining water transport in the xylem is critical for vascular plants to grow and survive. The drought-induced accumulation of embolism, when gas enters xylem conduits, causes declines in hydraulic conductance (K ) and is ultimately lethal. Several methods can be used to estimate the degree of embolism in xylem, from measuring K in tissues to directly visualising embolism in conduits. One method allowing a direct quantification of embolised xylem area is the optical vulnerability (OV) technique. This method has been used across different organs and has a high spatial and temporal resolution. Here, we review studies using the OV technique, discuss the main advantages and disadvantages of this method, and summarise key advances arising from its use. Vulnerability curves generated by the OV method are regularly comparable to other methods, including the centrifuge and X-ray microtomography. A major advantage of the OV technique over other methods is that it can be simultaneously used to determine in situ embolism formation in leaves, stems and roots, in species spanning the phylogeny of land plants. The OV method has been used to experimentally investigate the spreading of embolism through xylem networks, associate embolism with downstream tissue death, and observe embolism formation in the field.
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Affiliation(s)
- Amanda A Cardoso
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Cade N Kane
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
| | - Ian M Rimer
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
| | - Scott A M McAdam
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
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22
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Wagner Y, Feng F, Yakir D, Klein T, Hochberg U. In situ, direct observation of seasonal embolism dynamics in Aleppo pine trees growing on the dry edge of their distribution. THE NEW PHYTOLOGIST 2022; 235:1344-1350. [PMID: 35514143 PMCID: PMC9541785 DOI: 10.1111/nph.18208] [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: 02/15/2022] [Accepted: 04/30/2022] [Indexed: 06/14/2023]
Abstract
Xylem embolism impairs hydraulic conductivity in trees and drives drought-induced mortality. While embolism has been monitored in vivo in potted plants, and research has revealed evidence of embolism in field-grown trees, continuous in situ monitoring of cavitation in forests is lacking. Seasonal patterns of embolism were monitored in branchlets of Aleppo pine (Pinus halepensis) trees growing in a dry Mediterranean forest. Optical visualization (OV) sensors were installed on terminal branches, in addition to monthly sampling for micro computed tomography scans. We detected 208 cavitation events among four trees, which represented an embolism increase from zero to c. 12% along the dry season. Virtually all the cavitation events occurred during daytime hours, with 77% occurring between 10:00 and 17:00 h. The probability for cavitation in a given hour increased as vapor pressure deficit (VPD) increased, up to a probability of 42% for cavitation when VPD > 5 kPa. The findings uniquely reveal the instantaneous environmental conditions that lead to cavitation. The increased likelihood of cavitation events under high VPD in water-stressed pines is the first empirical support for this long hypothesized relationship. Our observations suggest that low levels of embolism are common in Aleppo pine trees at the dry edge of their distribution.
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Affiliation(s)
- Yael Wagner
- Plant & Environmental Sciences DepartmentWeizmann Institute of ScienceRehovot7610001Israel
| | - Feng Feng
- Institute of Soil, Water and Environmental SciencesVolcani CenterARORishon Lezion7505101Israel
| | - Dan Yakir
- Earth and Planetary Science DepartmentWeizmann Institute of ScienceRehovot7610001Israel
| | - Tamir Klein
- Plant & Environmental Sciences DepartmentWeizmann Institute of ScienceRehovot7610001Israel
| | - Uri Hochberg
- Institute of Soil, Water and Environmental SciencesVolcani CenterARORishon Lezion7505101Israel
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23
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Rodriguez‐Dominguez CM, Forner A, Martorell S, Choat B, Lopez R, Peters JMR, Pfautsch S, Mayr S, Carins‐Murphy MR, McAdam SAM, Richardson F, Diaz‐Espejo A, Hernandez‐Santana V, Menezes‐Silva PE, Torres‐Ruiz JM, Batz TA, Sack L. Leaf water potential measurements using the pressure chamber: Synthetic testing of assumptions towards best practices for precision and accuracy. PLANT, CELL & ENVIRONMENT 2022; 45:2037-2061. [PMID: 35394651 PMCID: PMC9322401 DOI: 10.1111/pce.14330] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/21/2022] [Accepted: 03/26/2022] [Indexed: 05/24/2023]
Abstract
Leaf water potential (ψleaf ), typically measured using the pressure chamber, is the most important metric of plant water status, providing high theoretical value and information content for multiple applications in quantifying critical physiological processes including drought responses. Pressure chamber measurements of ψleaf (ψleafPC ) are most typical, yet, the practical complexity of the technique and of the underlying theory has led to ambiguous understanding of the conditions to optimize measurements. Consequently, specific techniques and precautions diversified across the global research community, raising questions of reliability and repeatability. Here, we surveyed specific methods of ψleafPC from multiple laboratories, and synthesized experiments testing common assumptions and practices in ψleafPC for diverse species: (i) the need for equilibration of previously transpiring leaves; (ii) leaf storage before measurement; (iii) the equilibration of ψleaf for leaves on bagged branches of a range of dehydration; (iv) the equilibration of ψleaf across the lamina for bagged leaves, and the accuracy of measuring leaves with artificially 'elongated petioles'; (v) the need in ψleaf measurements for bagging leaves and high humidity within the chamber; (vi) the need to avoid liquid water on leaf surfaces; (vii) the use of 'pulse' pressurization versus gradual pressurization; and (viii) variation among experimenters in ψleafPC determination. Based on our findings we provide a best practice protocol to maximise accuracy, and provide recommendations for ongoing species-specific tests of important assumptions in future studies.
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Affiliation(s)
- Celia M. Rodriguez‐Dominguez
- Protection of the Soil, Plant, Water SystemIrrigation and Crop Ecophysiology Group, IRNAS‐CSICSevillaSpain
- Plant BiotechnologyLaboratory of Plant Molecular Ecophysiology, IRNAS‐CSICSevillaSpain
| | - Alicia Forner
- Department of Biogeography and Global Change, International Global Change Laboratory (LINCGlobal), Museo Nacional de Ciencias NaturalesConsejo Superior de Investigaciones CientíficasMadridSpain
- Department of Ecology, Centro de Investigaciones sobre Desertificación, Consejo Superior de Investigaciones Científicas (CSIC)University of València and Generalitat ValencianaValenciaSpain
| | - Sebastia Martorell
- Departament de Biologia, Research Group on Plant Biology under Mediterranean ConditionsUniversitat de les Illes BalearsPalma de MallorcaSpain
| | - Brendan Choat
- Plants, Animals and Interactions, Hawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNew South WalesAustralia
| | - Rosana Lopez
- Departamento de Sistemas y Recursos NaturalesUniversidad Politécnica de MadridMadridSpain
| | - Jennifer M. R. Peters
- Division of Environmental Science, Oak Ridge National LaboratoryClimate Change Science InstituteOak RidgeTennesseeUSA
| | - Sebastian Pfautsch
- Geography, Tourism and Urban Planning, Urban Studies, School of Social Science and PsychologyWestern Sydney UniversityPenrithNew South WalesAustralia
| | - Stefan Mayr
- Department of BotanyUniversity of InnsbruckInnsbruckAustria
| | - Madeline R. Carins‐Murphy
- Plant Sciences, Discipline of Biological Sciences, School of Natural SciencesUniversity of TasmaniaHobartAustralia
| | - Scott A. M. McAdam
- Department of Botany and Plant Pathology, Purdue Center for Plant BiologyPurdue UniversityWest LafayetteIndianaUSA
| | - Freya Richardson
- Plant Sciences, Discipline of Biological Sciences, School of Natural SciencesUniversity of TasmaniaHobartAustralia
| | - Antonio Diaz‐Espejo
- Protection of the Soil, Plant, Water SystemIrrigation and Crop Ecophysiology Group, IRNAS‐CSICSevillaSpain
- Plant BiotechnologyLaboratory of Plant Molecular Ecophysiology, IRNAS‐CSICSevillaSpain
| | - Virginia Hernandez‐Santana
- Protection of the Soil, Plant, Water SystemIrrigation and Crop Ecophysiology Group, IRNAS‐CSICSevillaSpain
- Plant BiotechnologyLaboratory of Plant Molecular Ecophysiology, IRNAS‐CSICSevillaSpain
| | - Paulo E. Menezes‐Silva
- Laboratory of Integrative Physics and Physiology of Trees in a Fluctuating EnvironmentUniversité Clermont‐Auvergne, INRAE, PIAFClermont‐FerrandFrance
| | - Jose M. Torres‐Ruiz
- Laboratory of Integrative Physics and Physiology of Trees in a Fluctuating EnvironmentUniversité Clermont‐Auvergne, INRAE, PIAFClermont‐FerrandFrance
| | - Timothy A. Batz
- Department of Botany and Plant Pathology, Purdue Center for Plant BiologyPurdue UniversityWest LafayetteIndianaUSA
| | - Lawren Sack
- Department of Ecology and Evolutionary BiologyUniversity of CaliforniaLos AngelesCaliforniaUSA
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24
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Lamacque L, Sabin F, Améglio T, Herbette S, Charrier G. Detection of acoustic events in lavender for measuring xylem vulnerability to embolism and cellular damage. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:3699-3710. [PMID: 35176148 DOI: 10.1093/jxb/erac061] [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: 08/16/2021] [Accepted: 02/15/2022] [Indexed: 06/14/2023]
Abstract
Acoustic emission analysis is promising to investigate the physiological events leading to drought-induced injury and mortality. However, their nature and source are not fully understood, making this technique difficult to use as a direct measure of the loss of xylem hydraulic conductance. Acoustic emissions were recorded during severe dehydration in lavender plants (Lavandula angustifolia) and compared with the dynamics of embolism development and cell damage. The timing and characteristics of acoustic signals from two independent recording systems were compared by principal component analysis (PCA). Changes in water potential, branch diameter, loss of hydraulic conductance, and cellular damage were also measured to quantify drought-induced damages. Two distinct phases of acoustic emissions were observed during dehydration: the first one associated with a rapid loss of diameter and a significant increase in loss of xylem conductance (90%), and the second with slower changes in diameter and a significant increase in cellular damage. Based on PCA, a developed algorithm discriminated hydraulic-related acoustic signals from other sources, proposing a reconstruction of hydraulic vulnerability curves. Cellular damage preceded by hydraulic failure seems to lead to a lack of recovery. The second acoustic phase would allow detection of plant mortality.
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Affiliation(s)
- Lia Lamacque
- Université Clermont Auvergne, INRAE, PIAF, F-63000 Clermont-Ferrand, France
- Institut Technique Interprofessionnel Plantes à Parfum, Médicinal, Aromatiques et Industrielles, 26740 Montboucher-sur-Jabron, France
- CNRS Aix-Marseille University, France
| | - Florian Sabin
- Université Clermont Auvergne, INRAE, PIAF, F-63000 Clermont-Ferrand, France
| | - Thierry Améglio
- Université Clermont Auvergne, INRAE, PIAF, F-63000 Clermont-Ferrand, France
| | - Stéphane Herbette
- Université Clermont Auvergne, INRAE, PIAF, F-63000 Clermont-Ferrand, France
| | - Guillaume Charrier
- Université Clermont Auvergne, INRAE, PIAF, F-63000 Clermont-Ferrand, France
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25
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Song J, Trueba S, Yin XH, Cao KF, Brodribb TJ, Hao GY. Hydraulic vulnerability segmentation in compound-leaved trees: Evidence from an embolism visualization technique. PLANT PHYSIOLOGY 2022; 189:204-214. [PMID: 35099552 PMCID: PMC9070814 DOI: 10.1093/plphys/kiac034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/27/2021] [Indexed: 05/11/2023]
Abstract
The hydraulic vulnerability segmentation (HVS) hypothesis implies the existence of differences in embolism resistance between plant organs along the xylem pathway and has been suggested as an adaptation allowing the differential preservation of more resource-rich tissues during drought stress. Compound leaves in trees are considered a low-cost means of increasing leaf area and may thus be expected to show evidence of strong HVS, given the tendency of compound-leaved tree species to shed their leaf units during drought. However, the existence and role of HVS in compound-leaved tree species during drought remain uncertain. We used an optical visualization technique to estimate embolism occurrence in stems, petioles, and leaflets of shoots in two compound-leaved tree species, Manchurian ash (Fraxinus mandshurica) and Manchurian walnut (Juglans mandshurica). We found higher (less negative) water potentials corresponding to 50% loss of conductivity (P50) in leaflets and petioles than in stems in both species. Overall, we observed a consistent pattern of stem > petiole > leaflet in terms of xylem resistance to embolism and hydraulic safety margins (i.e. the difference between mid-day water potential and P50). The coordinated variation in embolism vulnerability between organs suggests that during drought conditions, trees benefit from early embolism and subsequent shedding of more expendable organs such as leaflets and petioles, as this provides a degree of protection to the integrity of the hydraulic system of the more carbon costly stems. Our results highlight the importance of HVS as an adaptive mechanism of compound-leaved trees to withstand drought stress.
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Affiliation(s)
- Jia Song
- CAS Key Laboratory of Forest Ecology and Management & Key Laboratory of Terrestrial Ecosystem Carbon Neutrality Liaoning Province, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning, China
- School of Environmental and Geographical Science, Shanghai Normal University, Shanghai 200234, China
- Yangtze River Delta National Observatory of Wetland Ecosystem, Shanghai Normal University, Shanghai 200234, China
| | - Santiago Trueba
- University of Bordeaux, INRAE, BIOGECO, 33615 Pessac, France
| | - Xiao-Han Yin
- CAS Key Laboratory of Forest Ecology and Management & Key Laboratory of Terrestrial Ecosystem Carbon Neutrality Liaoning Province, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning, China
| | - Kun-Fang Cao
- Plant Ecophysiology and Evolution Group, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, and College of Forestry, Guangxi University, Nanning, Guangxi 530004, China
| | - Timothy J Brodribb
- Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia
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26
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Gauthey A, Backes D, Balland J, Alam I, Maher DT, Cernusak LA, Duke NC, Medlyn BE, Tissue DT, Choat B. The Role of Hydraulic Failure in a Massive Mangrove Die-Off Event. FRONTIERS IN PLANT SCIENCE 2022; 13:822136. [PMID: 35574083 PMCID: PMC9094047 DOI: 10.3389/fpls.2022.822136] [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: 11/25/2021] [Accepted: 03/25/2022] [Indexed: 06/15/2023]
Abstract
Between late 2015 and early 2016, more than 7,000 ha of mangrove forest died along the coastline of the Gulf of Carpentaria, in northern Australia. This massive die-off was preceded by a strong 2015/2016 El Niño event, resulting in lower precipitation, a drop in sea level and higher than average temperatures in northern Australia. In this study, we investigated the role of hydraulic failure in the mortality and recovery of the dominant species, Avicennia marina, 2 years after the mortality event. We measured predawn water potential (Ψpd) and percent loss of stem hydraulic conductivity (PLC) in surviving individuals across a gradient of impact. We also assessed the vulnerability to drought-induced embolism (Ψ50) for the species. Areas with severe canopy dieback had higher native PLC (39%) than minimally impacted areas (6%), suggesting that hydraulic recovery was ongoing. The high resistance of A. marina to water-stress-induced embolism (Ψ50 = -9.6 MPa), indicates that severe water stress (Ψpd < -10 MPa) would have been required to cause mortality in this species. Our data indicate that the natural gradient of water-stress enhanced the impact of El Niño, leading to hydraulic failure and mortality in A. marina growing on severely impacted (SI) zones. It is likely that lowered sea levels and less frequent inundation by seawater, combined with lower inputs of fresh water, high evaporative demand and high temperatures, led to the development of hyper-salinity and extreme water stress during the 2015/16 summer.
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Affiliation(s)
- Alice Gauthey
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
- Plant Ecology Research Laboratory PERL, Ecole Polytechnique Fédérale de Lausanne EPFL, Lausanne, Switzerland
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
| | - Diana Backes
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Jeff Balland
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Iftakharul Alam
- College of Science and Engineering, James Cook University, Cairns, QLD, Australia
| | - Damien T. Maher
- Faculty of Science and Engineering, Southern Cross University, Lismore, NSW, Australia
| | - Lucas A. Cernusak
- College of Science and Engineering, James Cook University, Cairns, QLD, Australia
| | - Norman C. Duke
- TropWATER Centre, James Cook University, Townsville, QLD, Australia
| | - Belinda E. Medlyn
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - David T. Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
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27
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Britton TG, Brodribb TJ, Richards SA, Ridley C, Hovenden MJ. Canopy damage during a natural drought depends on species identity, physiology and stand composition. THE NEW PHYTOLOGIST 2022; 233:2058-2070. [PMID: 34850394 DOI: 10.1111/nph.17888] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 11/21/2021] [Indexed: 06/13/2023]
Abstract
Vulnerability to xylem cavitation is a strong predictor of drought-induced damage in forest communities. However, biotic features of the community itself can influence water availability at the individual tree-level, thereby modifying patterns of drought damage. Using an experimental forest in Tasmania, Australia, we determined the vulnerability to cavitation (leaf P50 ) of four tree species and assessed the drought-induced canopy damage of 2944 6-yr-old trees after an extreme natural drought episode. We examined how individual damage was related to their size and the density and species identity of neighbouring trees. The two co-occurring dominant tree species, Eucalyptus delegatensis and Eucalyptus regnans, were the most vulnerable to drought-induced xylem cavitation and both species suffered significantly greater damage than neighbouring, subdominant species Pomaderris apetala and Acacia dealbata. While the two eucalypts had similar leaf P50 values, E. delegatensis suffered significantly greater damage, which was strongly related to the density of neighbouring P. apetala. Damage in E. regnans was less impacted by neighbouring plants and smaller trees of both eucalypts sustained significantly more damage than larger trees. Our findings demonstrate that natural drought damage is influenced by individual plant physiology as well as the composition, physiology and density of the surrounding stand.
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Affiliation(s)
- Travis G Britton
- Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tas., 7001, Australia
- ARC Training Centre for Forest Value, University of Tasmania, Hobart, Tas., 7001, Australia
| | - Timothy J Brodribb
- Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tas., 7001, Australia
| | - Shane A Richards
- School of Natural Sciences, University of Tasmania, Hobart, Tas., 7001, Australia
| | - Chantelle Ridley
- Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tas., 7001, Australia
| | - Mark J Hovenden
- Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tas., 7001, Australia
- ARC Training Centre for Forest Value, University of Tasmania, Hobart, Tas., 7001, Australia
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28
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Nie ZF, Liao ZQ, Yao GQ, Tian XQ, Bi MH, Teixeira da Silva JA, Gao TP, Fang XW. Divergent stem hydraulic strategies of Caragana korshinskii resprouts following a disturbance. TREE PHYSIOLOGY 2022; 42:325-336. [PMID: 34387352 DOI: 10.1093/treephys/tpab108] [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: 05/06/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
Resprouting plants are distributed in many vegetation communities worldwide. With increasing resprout age post-severe-disturbance, new stems grow rapidly at their early age, and decrease in their growth with gradually decreasing water status thereafter. However, there is little knowledge about how stem hydraulic strategies and anatomical traits vary post-disturbance. In this study, the stem water potential (Ψstem), maximum stem hydraulic conductivity (Kstem-max), water potential at 50% loss of hydraulic conductivity (Kstem P50) and anatomical traits of Caragana korshinkii resprouts were measured during a 1- to 13-year post-disturbance period. We found that the Kstem-max decreased with resprout age from 1-year-old resprouts (84.2 mol m-1 s-1 MPa-1) to 13-year-old resprouts (54.2 mol m-1 s-1 MPa-1) as a result of decreases in the aperture fraction (Fap) and the sum of aperture area on per unit intervessel wall area (Aap). The Kstem P50 of the resprouts decreased from 1-year-old resprouts (-1.8 MPa) to 13-year-old resprouts (-2.9 MPa) as a result of increases in vessel implosion resistance (t/b)2, wood density (WD), vessel grouping index (GI) and decreases in Fap and Aap. These shifts in hydraulic structure and function resulted in an age-based divergence in hydraulic strategies i.e., a change from an acquisitive strategy to a conservative strategy, with increasing resprout age post-disturbance.
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Affiliation(s)
- Zheng-Fei Nie
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Zhong-Qiang Liao
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Guang-Qian Yao
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Xue-Qian Tian
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Min-Hui Bi
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | | | - Tian-Peng Gao
- School of Biological and Environmental Engineering, Xi'an University, Xi'an 710065, China
| | - Xiang-Wen Fang
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
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OpenWeedLocator (OWL): an open-source, low-cost device for fallow weed detection. Sci Rep 2022; 12:170. [PMID: 34996963 PMCID: PMC8741824 DOI: 10.1038/s41598-021-03858-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Accepted: 12/03/2021] [Indexed: 11/08/2022] Open
Abstract
The use of a fallow phase is an important tool for maximizing crop yield potential in moisture limited agricultural environments, with a focus on removing weeds to optimize fallow efficiency. Repeated whole field herbicide treatments to control low-density weed populations is expensive and wasteful. Site-specific herbicide applications to low-density fallow weed populations is currently facilitated by proprietary, sensor-based spray booms. The use of image analysis for fallow weed detection is an opportunity to develop a system with potential for in-crop weed recognition. Here we present OpenWeedLocator (OWL), an open-source, low-cost and image-based device for fallow weed detection that improves accessibility to this technology for the weed control community. A comprehensive GitHub repository was developed, promoting community engagement with site-specific weed control methods. Validation of OWL as a low-cost tool was achieved using four, existing colour-based algorithms over seven fallow fields in New South Wales, Australia. The four algorithms were similarly effective in detecting weeds with average precision of 79% and recall of 52%. In individual transects up to 92% precision and 74% recall indicate the performance potential of OWL in fallow fields. OWL represents an opportunity to redefine the approach to weed detection by enabling community-driven technology development in agriculture.
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30
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Harrison Day BL, Carins-Murphy MR, Brodribb TJ. Reproductive water supply is prioritized during drought in tomato. PLANT, CELL & ENVIRONMENT 2022; 45:69-79. [PMID: 34705293 DOI: 10.1111/pce.14206] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 10/09/2021] [Accepted: 10/10/2021] [Indexed: 06/13/2023]
Abstract
Reproductive success largely defines the fitness of plant species. Understanding how heat and drought affect plant reproduction is thus key to predicting future plant fitness under rising global temperatures. Recent work suggests reproductive tissues are highly vulnerable to water stress in perennial plants where reproductive sacrifice could preserve plant survival. However, most crop species are annuals where such a strategy would theoretically reduce fitness. We examined the reproductive strategy of tomato (Solanum lycopersicum var. Rheinlands Ruhm) to determine whether water supply to fruits is prioritized above vegetative tissues during drought. Using optical methods, we mapped xylem cavitation and tissue shrinkage in vegetative and reproductive organs during dehydration to determine the priority of water flow under acute water stress. Stems and peduncles of tomato showed significantly greater xylem cavitation resistance than leaves. This maintenance of intact water supply enabled tomato fruit to continue to expand during acute water stress, utilizing xylem water made available by tissue collapse and early cavitation of leaves. Here, tomato plants prioritize water supply to reproductive tissues, maintaining fruit development under drought conditions. These results emphasize the critical role of water transport in shaping life history and suggest a broad relevance of hydraulic prioritization in plant ecology.
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Affiliation(s)
| | | | - Timothy J Brodribb
- School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia
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31
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Johnson KM, Lucani C, Brodribb TJ. In vivo monitoring of drought-induced embolism in Callitris rhomboidea trees reveals wide variation in branchlet vulnerability and high resistance to tissue death. THE NEW PHYTOLOGIST 2022; 233:207-218. [PMID: 34625973 DOI: 10.1111/nph.17786] [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: 07/01/2021] [Accepted: 10/01/2021] [Indexed: 06/13/2023]
Abstract
Damage to the plant water transport system through xylem cavitation is known to be a driver of plant death in drought conditions. However, a lack of techniques to continuously monitor xylem embolism in whole plants in vivo has hampered our ability to investigate both how this damage propagates and the possible mechanistic link between xylem damage and tissue death. Using optical and fluorescence sensors, we monitored drought-induced xylem embolism accumulation and photosynthetic damage in vivo throughout the canopy of a drought-resistant conifer, Callitris rhomboidea, during drought treatments of c. 1 month duration. We show that drought-induced damage to the xylem can be monitored in vivo in whole trees during extended periods of water stress. Under these conditions, vulnerability of the xylem to cavitation varied widely among branchlets, with photosynthetic damage only recorded once > 90% of the xylem was cavitated. The variation in branchlet vulnerability has important implications for understanding how trees like C. rhomboidea survive drought, and the high resistance of branchlets to tissue damage points to runaway cavitation as a likely driver of tissue death in C. rhomboidea branch tips.
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Affiliation(s)
- Kate M Johnson
- Discipline of Biological Sciences, School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS, 7001, Australia
| | - Christopher Lucani
- Discipline of Biological Sciences, School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS, 7001, Australia
| | - Timothy J Brodribb
- Discipline of Biological Sciences, School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS, 7001, Australia
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32
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Avila RT, Cardoso AA, Batz TA, Kane CN, DaMatta FM, McAdam SAM. Limited plasticity in embolism resistance in response to light in leaves and stems in species with considerable vulnerability segmentation. PHYSIOLOGIA PLANTARUM 2021; 172:2142-2152. [PMID: 33942915 DOI: 10.1111/ppl.13450] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 04/23/2021] [Accepted: 04/30/2021] [Indexed: 06/12/2023]
Abstract
Xylem resistance to embolism is a key metric determining plant survival during drought. Yet, we have a limited understanding of the degree of plasticity in vulnerability to embolism. Here, we tested whether light availability influences embolism resistance in leaves and stems. The optical vulnerability method was used to assess stem and leaf resistance to embolism in Phellodendron amurense and Ilex verticillata acclimated to sun and shade microenvironments within the same canopy. In both species, we found considerable segmentation in xylem resistance to embolism between leaves and stems, but only minor acclimation in response to light availability. With the addition of a third species, Betula pubescens, which shows no vulnerability segmentation, we sought to investigate xylem anatomical traits that might correlate with strong vulnerability segmentation. We found a correlation between the area fraction of vessels in the xylem and embolism resistance across species and tissue types. Our results suggest that minimal acclimation of embolism resistance occurs in response to light environment in the same individual and that the degree of vulnerability segmentation between leaves and stems might be determined by the vessel lumen fraction of the xylem.
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Affiliation(s)
- Rodrigo T Avila
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Brazil
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Amanda A Cardoso
- Instituto de Ciências da Natureza, Universidade Federal de Alfenas, Alfenas, Brazil
| | - Timothy A Batz
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Cade N Kane
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Fábio M DaMatta
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Brazil
| | - Scott A M McAdam
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
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33
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Zhang FP, Zhang JL, Brodribb TJ, Hu H. Cavitation resistance of peduncle, petiole and stem is correlated with bordered pit dimensions in Magnolia grandiflora. PLANT DIVERSITY 2021; 43:324-330. [PMID: 34485775 PMCID: PMC8390921 DOI: 10.1016/j.pld.2020.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 11/04/2020] [Accepted: 11/05/2020] [Indexed: 05/05/2023]
Abstract
Variation in resistance of xylem to embolism among flowers, leaves, and stems strongly influences the survival and reproduction of plants. However, little is known about the vulnerability to xylem embolism under drought stress and their relationships to the anatomical traits of pits among reproductive and vegetative organs. In this study, we investigated the variation in xylem vulnerability to embolism in peduncles, petioles, and stems in a woody plant, Magnolia grandiflora. We analyzed the relationships between water potentials that induced 50% embolism (P50) in peduncles, petioles, and stems and the conduit pit traits hypothesized to influence cavitation resistance. We found that peduncles were more vulnerable to cavitation than petioles and stems, supporting the hypothesis of hydraulic vulnerability segmentation that leaves and stems are prioritized over flowers during drought stress. Moreover, P50 was significantly correlated with variation in the dimensions of inter-vessel pit apertures among peduncles, petioles and stems. These findings highlight that measuring xylem vulnerability to embolism in reproductive organs is essential for understanding the effect of drought on plant reproductive success and mortality under drought stress.
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Affiliation(s)
- Feng-Ping Zhang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, Yunnan, China
- College of Traditional Chinese Medicine, Yunnan Key Laboratory of Dai and Yi Medicines, Yunnan University of Chinese Medicine, Kunming, 650500, Yunnan, China
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences, Yunnan Key Laboratory for Wild Plant Resources, Kunming 650201, Yunnan, China
| | - Jiao-Lin Zhang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, Yunnan, China
- Corresponding author.
| | - Timothy J. Brodribb
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
| | - Hong Hu
- Key Laboratory of Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences, Yunnan Key Laboratory for Wild Plant Resources, Kunming 650201, Yunnan, China
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Zhang FP, Huang JL, Fu XW, Huang W, Zhang SB. Peduncle vulnerability to embolism is related to conduit dimensions of the critically endangered slipper orchids in Southwest China. Glob Ecol Conserv 2021. [DOI: 10.1016/j.gecco.2021.e01654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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35
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Tomasella M, Casolo V, Natale S, Petruzzellis F, Kofler W, Beikircher B, Mayr S, Nardini A. Shade-induced reduction of stem nonstructural carbohydrates increases xylem vulnerability to embolism and impedes hydraulic recovery in Populus nigra. THE NEW PHYTOLOGIST 2021; 231:108-121. [PMID: 33811346 PMCID: PMC9290559 DOI: 10.1111/nph.17384] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 03/28/2021] [Indexed: 05/08/2023]
Abstract
Nonstructural carbohydrates (NSCs) have been suggested to affect xylem transport under fluctuating water availability, but conclusive evidence is still lacking. We tested the effect of shade-induced NSC depletion on xylem vulnerability to embolism and hydraulic recovery on Populus nigra saplings. Vulnerability was assessed in light-exposed (L) and shaded (S) plants with the hydraulic method, and in vivo with the optical method and X-ray micro-computed tomography. Plants were stressed to 80% loss of hydraulic conductance (PLC) and re-irrigated to check for possible recovery. We measured PLC, bark and wood NSC content, as well as xylem sap pH, surface tension (γsap ) and sugar concentration, before, during and after drought. Shading induced depletion of stem NSC (mainly starch) reserves. All methods converged in indicating higher xylem vulnerability in S than in L plants. This difference was not explained by xylem vessel and pit anatomy or by γsap . Shading impeded sap acidification and sugar accumulation during drought in S plants and prevented hydraulic recovery, which was observed in L plants. Our results highlight the importance of stem NSCs to sustain xylem hydraulic functioning during drought and suggest that light and/or adequate stem NSC thresholds are required to trigger xylem sap chemical changes involved in embolism recovery.
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Affiliation(s)
- Martina Tomasella
- Dipartimento di Scienze della VitaUniversità di TriesteVia L. Giorgieri 10Trieste34127Italy
| | - Valentino Casolo
- Dipartimento di Scienze AgroalimentariAmbientali e AnimaliUniversità di UdineVia delle Scienze 91Udine33100Italy
| | - Sara Natale
- Dipartimento di Scienze della VitaUniversità di TriesteVia L. Giorgieri 10Trieste34127Italy
| | - Francesco Petruzzellis
- Dipartimento di Scienze della VitaUniversità di TriesteVia L. Giorgieri 10Trieste34127Italy
| | - Werner Kofler
- Department of BotanyUniversity of InnsbruckSternwartestraße 15Innsbruck6020Austria
| | - Barbara Beikircher
- Department of BotanyUniversity of InnsbruckSternwartestraße 15Innsbruck6020Austria
| | - Stefan Mayr
- Department of BotanyUniversity of InnsbruckSternwartestraße 15Innsbruck6020Austria
| | - Andrea Nardini
- Dipartimento di Scienze della VitaUniversità di TriesteVia L. Giorgieri 10Trieste34127Italy
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36
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Degraeve S, De Baerdemaeker NJF, Ameye M, Leroux O, Haesaert GJW, Steppe K. Acoustic Vulnerability, Hydraulic Capacitance, and Xylem Anatomy Determine Drought Response of Small Grain Cereals. FRONTIERS IN PLANT SCIENCE 2021; 12:599824. [PMID: 34113357 PMCID: PMC8186553 DOI: 10.3389/fpls.2021.599824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 04/12/2021] [Indexed: 06/01/2023]
Abstract
Selection of high-yielding traits in cereal plants led to a continuous increase in productivity. However, less effort was made to select on adaptive traits, favorable in adverse and harsh environments. Under current climate change conditions and the knowledge that cereals are staple foods for people worldwide, it is highly important to shift focus to the selection of traits related to drought tolerance, and to evaluate new tools for efficient selection. Here, we explore the possibility to use vulnerability to drought-induced xylem embolism of wheat cultivars Excalibur and Hartog (Triticum aestivum L.), rye cultivar Duiker Max (Secale cereale L.), and triticale cultivars Dublet and US2014 (x Triticosecale Wittmack) as a proxy for their drought tolerance. Multiple techniques were combined to underpin this hypothesis. During bench-top dehydration experiments, acoustic emissions (AEs) produced by formation of air emboli were detected, and hydraulic capacitances quantified. By only looking at the AE50 values, one would classify wheat cultivar Excalibur as most tolerant and triticale cultivar Dublet as most vulnerable to drought-induced xylem embolism, though Dublet had significantly higher hydraulic capacitances, which are essential in terms of internal water storage to temporarily buffer or delay water shortage. In addition, xylem anatomical traits revealed that both cultivars have a contrasting trade-off between hydraulic safety and efficiency. This paper emphasizes the importance of including a cultivar's hydraulic capacitance when evaluating its drought response and vulnerability to drought-induced xylem embolism, instead of relying on the AE50 as the one parameter.
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Affiliation(s)
- Szanne Degraeve
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
- Laboratory of Applied Mycology and Phenomics, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Niels J. F. De Baerdemaeker
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Maarten Ameye
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
- Laboratory of Applied Mycology and Phenomics, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Olivier Leroux
- Department of Biology, Faculty of Sciences, Ghent University, Ghent, Belgium
| | | | - Kathy Steppe
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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37
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Nolan RH, Gauthey A, Losso A, Medlyn BE, Smith R, Chhajed SS, Fuller K, Song M, Li X, Beaumont LJ, Boer MM, Wright IJ, Choat B. Hydraulic failure and tree size linked with canopy die-back in eucalypt forest during extreme drought. THE NEW PHYTOLOGIST 2021; 230:1354-1365. [PMID: 33629360 DOI: 10.1111/nph.17298] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 02/17/2021] [Indexed: 06/12/2023]
Abstract
Eastern Australia was subject to its hottest and driest year on record in 2019. This extreme drought resulted in massive canopy die-back in eucalypt forests. The role of hydraulic failure and tree size on canopy die-back in three eucalypt tree species during this drought was examined. We measured pre-dawn and midday leaf water potential (Ψleaf ), per cent loss of stem hydraulic conductivity and quantified hydraulic vulnerability to drought-induced xylem embolism. Tree size and tree health was also surveyed. Trees with most, or all, of their foliage dead exhibited high rates of native embolism (78-100%). This is in contrast to trees with partial canopy die-back (30-70% canopy die-back: 72-78% native embolism), or relatively healthy trees (little evidence of canopy die-back: 25-31% native embolism). Midday Ψleaf was significantly more negative in trees exhibiting partial canopy die-back (-2.7 to -6.3 MPa), compared with relatively healthy trees (-2.1 to -4.5 MPa). In two of the species the majority of individuals showing complete canopy die-back were in the small size classes. Our results indicate that hydraulic failure is strongly associated with canopy die-back during drought in eucalypt forests. Our study provides valuable field data to help constrain models predicting mortality risk.
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Affiliation(s)
- Rachael H Nolan
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- Bushfire Risk Management Research Hub, Wollongong, NSW, 2522, Australia
| | - Alice Gauthey
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Adriano Losso
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- Department of Botany, University of Innsbruck, Sternwartestraße 15, Innsbruck, 6020, Austria
| | - Belinda E Medlyn
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Rhiannon Smith
- Ecosystem Management, University of New England, Armidale, NSW, 2351, Australia
| | - Shubham S Chhajed
- Department of Biological Sciences, Macquarie University, Macquarie Park, NSW, 2109, Australia
| | - Kathryn Fuller
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- Bushfire Risk Management Research Hub, Wollongong, NSW, 2522, Australia
| | - Magnolia Song
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Xine Li
- Department of Biological Sciences, Macquarie University, Macquarie Park, NSW, 2109, Australia
- Department of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, 225009, China
| | - Linda J Beaumont
- Department of Biological Sciences, Macquarie University, Macquarie Park, NSW, 2109, Australia
| | - Matthias M Boer
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
- Bushfire Risk Management Research Hub, Wollongong, NSW, 2522, Australia
| | - Ian J Wright
- Department of Biological Sciences, Macquarie University, Macquarie Park, NSW, 2109, Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
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38
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Mantova M, Menezes-Silva PE, Badel E, Cochard H, Torres-Ruiz JM. The interplay of hydraulic failure and cell vitality explains tree capacity to recover from drought. PHYSIOLOGIA PLANTARUM 2021; 172:247-257. [PMID: 33432594 DOI: 10.1111/ppl.13331] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 12/16/2020] [Accepted: 01/05/2021] [Indexed: 06/12/2023]
Abstract
Global climatic models predict an increment in the frequency and intensity of drought events, which have important consequences on forest dieback. However, the mechanisms leading to tree mortality under drought conditions and the physiological thresholds for recovery are not totally understood yet. This study aimed to identify what are the key physiological traits that determine the tree capacity to recover from drought. Individuals of a conifer (Pseudotsuga menziesii M.) and an angiosperm (Prunus lusitanica L.) species were exposed to drought and their ability to recover after rehydration monitored. Results showed that the actual thresholds used for recovery from drought based on percentage loss of conductance (PLC) (i.e., 50% for conifers, 88% for angiosperms) do not provide accurate insights about the tree capacity for surviving extreme drought events. On the contrary, differences in stem relative water content (RWCStem ) and the level of electrolytes leakage (EL) were directly related to the capacity of the trees to recover from drought. This was the case for the conifer species, P. menziesii, for which higher RWCStem and lower EL values were related to the recovery capacity. Even if results showed a similar trend for the angiosperm P. lusitanica as for the conifers, differences between the two traits were much more subtle and did not allow an accurate differentiation between trees able to recover and those that were not. RWCStem and EL could work as indicators of tree capacity to recover from drought for conifers but more studies are required to confirm this observation for angiosperms.
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Affiliation(s)
- Marylou Mantova
- Université Clermont Auvergne, INRAE, PIAF, Clermont-Ferrand, France
| | - Paulo E Menezes-Silva
- Laboratório de Fisiologia Vegetal, Instituto Federal de Educação, Ciência e Tecnologia Goiano, Goiânia, Brazil
| | - Eric Badel
- Université Clermont Auvergne, INRAE, PIAF, Clermont-Ferrand, France
| | - Hervé Cochard
- Université Clermont Auvergne, INRAE, PIAF, Clermont-Ferrand, France
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39
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Guan X, Pereira L, McAdam SAM, Cao KF, Jansen S. No gas source, no problem: Proximity to pre-existing embolism and segmentation affect embolism spreading in angiosperm xylem by gas diffusion. PLANT, CELL & ENVIRONMENT 2021; 44:1329-1345. [PMID: 33529382 DOI: 10.1111/pce.14016] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 01/16/2021] [Accepted: 01/17/2021] [Indexed: 05/12/2023]
Abstract
Embolism spreading in dehydrating angiosperm xylem is driven by gas movement between embolized and sap-filled conduits. Here we examine how the proximity to pre-existing embolism and hydraulic segmentation affect embolism propagation. Based on the optical method, we compare xylem embolism resistance between detached leaves and leaves attached to branches, and between intact leaves and leaves with cut minor veins, for six species. Embolism resistance of detached leaves was significantly lower than that of leaves attached to stems, except for two species, with all vessels ending in their petioles. Cutting of minor veins showed limited embolism spreading in minor veins near the cuts prior to major veins. Moreover, despite strong agreement in the overall embolism resistance of detached leaves between the optical and pneumatic method, minor differences were observed during early stages of embolism formation. We conclude that embolism resistance may represent a relative trait due to an open-xylem artefact, with embolism spreading possibly affected by the proximity and connectivity to pre-existing embolism as a gas source, while hydraulic segmentation prevents such artefact. Since embolism formation may not rely on a certain pressure difference threshold between functional and embolized conduits, we speculate that embolism is facilitated by pressure-driven gas diffusion across pit membranes.
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Affiliation(s)
- Xinyi Guan
- Institute of Systematic Botany and Ecology, Ulm University, Ulm, Germany
| | - Luciano Pereira
- Institute of Systematic Botany and Ecology, Ulm University, Ulm, Germany
- Laboratory of Plant Physiology "Coaracy M. Franco", Center R&D in Ecophysiology and Biophysics, Agronomic Institute (IAC), Campinas, Brazil
- Laboratory of Crop Physiology, Department of Plant Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, Brazil
| | - Scott A M McAdam
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA
| | - Kun-Fang Cao
- Plant Ecophysiology and Evolution Group, State Key Laboratory for Conservation and Utilisation of Subtropical Agro-Bioresources, Guangxi University, Nanning, China
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, China
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Ulm, Germany
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40
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Skelton RP, Anderegg LDL, Diaz J, Kling MM, Papper P, Lamarque LJ, Delzon S, Dawson TE, Ackerly DD. Evolutionary relationships between drought-related traits and climate shape large hydraulic safety margins in western North American oaks. Proc Natl Acad Sci U S A 2021; 118:e2008987118. [PMID: 33649205 PMCID: PMC7958251 DOI: 10.1073/pnas.2008987118] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Quantitative knowledge of xylem physical tolerance limits to dehydration is essential to understanding plant drought tolerance but is lacking in many long-vessel angiosperms. We examine the hypothesis that a fundamental association between sustained xylem water transport and downstream tissue function should select for xylem that avoids embolism in long-vessel trees by quantifying xylem capacity to withstand air entry of western North American oaks (Quercus spp.). Optical visualization showed that 50% of embolism occurs at water potentials below -2.7 MPa in all 19 species, and -6.6 MPa in the most resistant species. By mapping the evolution of xylem vulnerability to embolism onto a fossil-dated phylogeny of the western North American oaks, we found large differences between clades (sections) while closely related species within each clade vary little in their capacity to withstand air entry. Phylogenetic conservatism in xylem physical tolerance, together with a significant correlation between species distributions along rainfall gradients and their dehydration tolerance, suggests that closely related species occupy similar climatic niches and that species' geographic ranges may have shifted along aridity gradients in accordance with their physical tolerance. Such trends, coupled with evolutionary associations between capacity to withstand xylem embolism and other hydraulic-related traits, yield wide margins of safety against embolism in oaks from diverse habitats. Evolved responses of the vascular system to aridity support the embolism avoidance hypothesis and reveal the importance of quantifying plant capacity to withstand xylem embolism for understanding function and biogeography of some of the Northern Hemisphere's most ecologically and economically important plants.
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Affiliation(s)
- Robert P Skelton
- Department of Integrative Biology, University of California, Berkeley, CA 94720;
- Fynbos Node, South African Environmental Observation Network, Newlands 7735, Cape Town, South Africa
| | - Leander D L Anderegg
- Department of Integrative Biology, University of California, Berkeley, CA 94720
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93117
| | - Jessica Diaz
- Department of Integrative Biology, University of California, Berkeley, CA 94720
| | - Matthew M Kling
- Department of Integrative Biology, University of California, Berkeley, CA 94720
| | - Prahlad Papper
- Department of Integrative Biology, University of California, Berkeley, CA 94720
| | - Laurent J Lamarque
- Département des Sciences de l'Environnement, Université du Québec à Trois-Rivières, Trois-Rivières, QC G9A 5H7, Canada
- Université de Bordeaux, INRAE (Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement), UMR BIOGECO, 33615 Pessac, France
| | - Sylvain Delzon
- Université de Bordeaux, INRAE (Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement), UMR BIOGECO, 33615 Pessac, France
| | - Todd E Dawson
- Department of Integrative Biology, University of California, Berkeley, CA 94720
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720
| | - David D Ackerly
- Department of Integrative Biology, University of California, Berkeley, CA 94720
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720
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41
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Chen YJ, Maenpuen P, Zhang YJ, Barai K, Katabuchi M, Gao H, Kaewkamol S, Tao LB, Zhang JL. Quantifying vulnerability to embolism in tropical trees and lianas using five methods: can discrepancies be explained by xylem structural traits? THE NEW PHYTOLOGIST 2021; 229:805-819. [PMID: 32929748 DOI: 10.1111/nph.16927] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 08/18/2020] [Indexed: 05/21/2023]
Abstract
Vulnerability curves (VCs) describe the loss of hydraulic conductance against increasing xylem tension, providing valuable insights about the response of plant water transport to water stress. Techniques to construct VCs have been developed and modified continuously, but controversies continue. We compared VCs constructed using the bench-top dehydration (BD), air-injection-flow (AI), pneumatic-air-discharge (PAD), optical (OP) and X-ray-computed microtomography (MicroCT) methods for tropical trees and lianas with contrasting vessel lengths. The PAD method generated highly vulnerable VCs, the AI method intermediate VCs, whereas the BD, OP and MicroCT methods produced comparable and more resistant VCs. Vessel-length and diameter accounted for the overestimation ratio of vulnerability estimated using the AI but not the PAD method. Compared with directly measured midday embolism levels, the PAD and AI methods substantially overestimated embolism, whereas the BD, MicroCT and OP methods provided more reasonable estimations. Cut-open vessels, uncertainties in maximum air volume estimations, sample-length effects, tissue cracks and shrinkage together may impede the reliability of the PAD method. In conclusion, we validate the BD, OP and MicroCT methods for tropical plants, whereas the PAD and AI need further mechanistic testing. Therefore, applications of VCs in estimating plant responses to drought need to be cautious.
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Affiliation(s)
- Ya-Jun Chen
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
- Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
- Yuanjiang Savanna Ecosystem Research Station, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yuanjiang, Yunnan, 653300, China
| | - Phisamai Maenpuen
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yong-Jiang Zhang
- School of Biology and Ecology, University of Maine, Orono, ME, 04469, USA
| | - Kallol Barai
- School of Biology and Ecology, University of Maine, Orono, ME, 04469, USA
| | - Masatoshi Katabuchi
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
- Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
| | - Hui Gao
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Sasiwimol Kaewkamol
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lian-Bin Tao
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
| | - Jiao-Lin Zhang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
- Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla, Yunnan, 666303, China
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42
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Gauthey A, Peters JMR, Carins-Murphy MR, Rodriguez-Dominguez CM, Li X, Delzon S, King A, López R, Medlyn BE, Tissue DT, Brodribb TJ, Choat B. Visual and hydraulic techniques produce similar estimates of cavitation resistance in woody species. THE NEW PHYTOLOGIST 2020; 228:884-897. [PMID: 32542732 DOI: 10.1111/nph.16746] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 06/02/2020] [Indexed: 05/24/2023]
Abstract
Hydraulic failure of the plant vascular system is a principal cause of forest die-off under drought. Accurate quantification of this process is essential to our understanding of the physiological mechanisms underpinning plant mortality. Imaging techniques increasingly are applied to estimate xylem cavitation resistance. These techniques allow for in situ measurement of embolism formation in real time, although the benefits and trade-offs associated with different techniques have not been evaluated in detail. Here we compare two imaging methods, microcomputed tomography (microCT) and optical vulnerability (OV), to standard hydraulic methods for measurement of cavitation resistance in seven woody species representing a diversity of major phylogenetic and xylem anatomical groups. Across the seven species, there was strong agreement between cavitation resistance values (P50 ) estimated from visualization techniques (microCT and OV) and between visual techniques and hydraulic techniques. The results indicate that visual techniques provide accurate estimates of cavitation resistance and the degree to which xylem hydraulic function is impacted by embolism. Results are discussed in the context of trade-offs associated with each technique and possible causes of discrepancy between estimates of cavitation resistance provided by visual and hydraulic techniques.
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Affiliation(s)
- Alice Gauthey
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
| | - Jennifer M R Peters
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
| | - Madeline R Carins-Murphy
- School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tas, 7001, Australia
| | - Celia M Rodriguez-Dominguez
- School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tas, 7001, Australia
- Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes, 10, Sevilla, 41012, Spain
| | - Ximeng Li
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
| | - Sylvain Delzon
- UMR BIOGECO, INRA, Univ Bordeaux, Talence, 33450, France
| | - Andrew King
- L'Orme de Merisiers, Synchrotron SOLEIL, 91190 Saint-Aubin-BP48, Gif-sur-Yvette Cedex, France
| | - Rosana López
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
- Departamento de Sistemas y Recursos Naturales, Universidad Politécnica de Madrid, Madrid, Spain
- PIAF, INRA, University of Clermont-Auvergne, 63100, Clermont-Ferrand, France
| | - Belinda E Medlyn
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
| | - Tim J Brodribb
- School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tas, 7001, Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
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43
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Levionnois S, Ziegler C, Jansen S, Calvet E, Coste S, Stahl C, Salmon C, Delzon S, Guichard C, Heuret P. Vulnerability and hydraulic segmentations at the stem-leaf transition: coordination across Neotropical trees. THE NEW PHYTOLOGIST 2020; 228:512-524. [PMID: 32496575 DOI: 10.1111/nph.16723] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 05/18/2020] [Indexed: 05/23/2023]
Abstract
Hydraulic segmentation at the stem-leaf transition predicts higher hydraulic resistance in leaves than in stems. Vulnerability segmentation, however, predicts lower embolism resistance in leaves. Both mechanisms should theoretically favour runaway embolism in leaves to preserve expensive organs such as stems, and should be tested for any potential coordination. We investigated the theoretical leaf-specific conductivity based on an anatomical approach to quantify the degree of hydraulic segmentation across 21 tropical rainforest tree species. Xylem resistance to embolism in stems (flow-centrifugation technique) and leaves (optical visualization method) was quantified to assess vulnerability segmentation. We found a pervasive hydraulic segmentation across species, but with a strong variability in the degree of segmentation. Despite a clear continuum in the degree of vulnerability segmentation, eight species showed a positive vulnerability segmentation (leaves less resistant to embolism than stems), whereas the remaining species studied exhibited a negative or no vulnerability segmentation. The degree of vulnerability segmentation was positively related to the degree of hydraulic segmentation, such that segmented species promote both mechanisms to hydraulically decouple leaf xylem from stem xylem. To what extent hydraulic and vulnerability segmentation determine drought resistance requires further integration of the leaf-stem transition at the whole-plant level, including both xylem and outer xylem tissue.
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Affiliation(s)
- Sébastien Levionnois
- UMR EcoFoG, AgroParisTech, CIRAD, CNRS, INRAE, Université des Antilles, Université de Guyane, Kourou, 97310, France
- AMAP , Univ Montpellier , CIRAD, CNRS, INRAE, IRD, Montpellier, 34000, France
| | - Camille Ziegler
- UMR EcoFoG, AgroParisTech, CIRAD, CNRS, INRAE, Université des Antilles, Université de Guyane, Kourou, 97310, France
- UMR SILVA, INRAE , Université de Lorraine, Nancy, 54000, France
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Ulm, D-89081, Germany
| | - Emma Calvet
- UMR EcoFoG, AgroParisTech, CIRAD, CNRS, INRAE, Université des Antilles, Université de Guyane, Kourou, 97310, France
| | - Sabrina Coste
- UMR EcoFoG, AgroParisTech, CIRAD, CNRS, INRAE, Université des Antilles, Université de Guyane, Kourou, 97310, France
| | - Clément Stahl
- UMR EcoFoG, AgroParisTech, CIRAD, CNRS, INRAE, Université des Antilles, Université de Guyane, Kourou, 97310, France
| | - Camille Salmon
- AMAP , Univ Montpellier , CIRAD, CNRS, INRAE, IRD, Montpellier, 34000, France
| | - Sylvain Delzon
- Univ. Bordeaux , INRAE, BIOGECO, Pessac, F-33615, France
| | - Charlotte Guichard
- UMR EcoFoG, AgroParisTech, CIRAD, CNRS, INRAE, Université des Antilles, Université de Guyane, Kourou, 97310, France
| | - Patrick Heuret
- UMR EcoFoG, AgroParisTech, CIRAD, CNRS, INRAE, Université des Antilles, Université de Guyane, Kourou, 97310, France
- AMAP , Univ Montpellier , CIRAD, CNRS, INRAE, IRD, Montpellier, 34000, France
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44
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Shihan A, Volaire F, Hättenschwiler S. Neighbor identity affects growth and survival of Mediterranean plants under recurrent drought. Oecologia 2020; 194:555-569. [PMID: 32880027 DOI: 10.1007/s00442-020-04739-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 08/19/2020] [Indexed: 10/23/2022]
Abstract
The increasing intensity and frequency of droughts predicted for the Mediterranean basin with ongoing climate change will impact plant communities and ecosystem functioning. This study investigated the effect of severe recurrent droughts and the role of the neighbor plant identity on the growth and survival of three abundant and co-existing species of a typical Mediterranean shrubland. Two juvenile plants, either of the same species or in all possible combinations of the two woody species Quercus coccifera and Cistus albidus and the perennial grass species Brachypodium retusum were grown together in rhizotrons under controlled watering regimes for two years. Compared to a treatment with only one drought cycle, three successive droughts reduced the relative growth rates (RGR) of shoots and roots in B. retusum, but not in woody species, and increased the mortality of the woody species, but not that of the grass. The survival of C. albidus and of B. retusum, but not of Q. coccifera, increased when the neighbor individual was a different species than when it was the same species. Our data suggest that both species composition and frequency of drought events will impact the dynamics of plant communities in Mediterranean shrublands under ongoing climate change. The abundance of dehydration sensitive woody species will likely decrease under more frequent drought events at the expense of dehydration-tolerant grass species, resulting in potentially strong changes in the functioning of these ecosystems.
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Affiliation(s)
- Ammar Shihan
- CEFE, Univ. Montpellier, CNRS, INRAE, Univ. Paul-Valéry Montpellier 3, EPHE, IRD, Montpellier, France. .,Department of Renewable Natural Resources and Environment, Faculty of Agricultural, Aleppo University, Aleppo, Syria.
| | - Florence Volaire
- CEFE, Univ. Montpellier, CNRS, INRAE, Univ. Paul-Valéry Montpellier 3, EPHE, IRD, Montpellier, France
| | - Stephan Hättenschwiler
- CEFE, Univ. Montpellier, CNRS, INRAE, Univ. Paul-Valéry Montpellier 3, EPHE, IRD, Montpellier, France
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45
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Johnson KM, Brodersen C, Carins-Murphy MR, Choat B, Brodribb TJ. Xylem Embolism Spreads by Single-Conduit Events in Three Dry Forest Angiosperm Stems. PLANT PHYSIOLOGY 2020; 184:212-222. [PMID: 32581116 PMCID: PMC7479884 DOI: 10.1104/pp.20.00464] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 06/15/2020] [Indexed: 05/02/2023]
Abstract
Xylem cavitation resulting in air embolism is a major cause of plant death during drought, yet the spread of embolism throughout the plant water transport system is poorly understood. Our study used optical visualization and x-ray microcomputed tomography imaging to capture the spread of emboli in stems of three drought-resistant angiosperm trees: drooping she-oak (Allocasuarina verticillata), black wattle (Acacia mearnsii), and blue gum (Eucalyptus globulus). These species have similar degrees of xylem network connectivity (vessel grouping) with largely solitary vessels. The high temporal resolution of the optical vulnerability technique revealed that in current year branches, >80% of the cavitation events were discrete, temporally separated events in single vessels. This suggests that in xylem networks with low connectivity, embolism spread between conduits leading to multiple conduit cavitation events is uncommon. A. mearnsii showed both the highest number of multivessel cavitation events and the highest degree of vessel connectivity, suggesting a link between vessel arrangement and embolism spread. Knowledge of embolism spread will help us to uncover the links between xylem anatomy, arrangement, and the path of water flow in the xylem in diverse species to ultimately understand the drivers of cavitation and plant vulnerability to drought.
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Affiliation(s)
- Kate M Johnson
- Discipline of Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Craig Brodersen
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511
| | - Madeline R Carins-Murphy
- Discipline of Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales 2750, Australia
| | - Timothy J Brodribb
- Discipline of Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia
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46
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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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47
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Brodribb TJ, Carriquí M, Delzon S, McAdam SAM, Holbrook NM. Advanced vascular function discovered in a widespread moss. NATURE PLANTS 2020; 6:273-279. [PMID: 32170283 DOI: 10.1038/s41477-020-0602-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 01/22/2020] [Indexed: 05/13/2023]
Abstract
The evolution of terrestrial plants capable of growing upwards into the dry atmosphere profoundly transformed the Earth. A transition from small, 'non-vascular' bryophytes to arborescent vascular plants during the Devonian period is partially attributed to the evolutionary innovation of an internal vascular system capable of functioning under the substantial water tension associated with vascular water transport. Here, we show that vascular function in one of the most widespread living bryophytes (Polytrichum commune) exhibits strong functional parallels with the vascular systems of higher plants. These parallels include vascular conduits in Polytrichum that resist buckling while transporting water under tension, and leaves capable of regulating transpiration, permitting photosynthetic gas exchange without cavitation inside the vascular system. The advanced vascular function discovered in this tallest bryophyte family contrasts with the highly inefficient water use found in their leaves, emphasizing the importance of stomatal evolution enabling photosynthesis far above the soil surface.
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Affiliation(s)
- T J Brodribb
- School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia.
| | - M Carriquí
- School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia
- Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears - Instituto de Investigaciones Agroambientales y de la Economía del Agua, Palma, Spain
| | - S Delzon
- Université Bordeaux, BIOGECO, INRAE, Pessac, France
| | - S A M McAdam
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
| | - N M Holbrook
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA.
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48
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Smith‐Martin CM, Skelton RP, Johnson KM, Lucani C, Brodribb TJ. Lack of vulnerability segmentation among woody species in a diverse dry sclerophyll woodland community. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13519] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Chris M. Smith‐Martin
- Department of Ecology, Evolution and Evolutionary Biology Columbia University New York NY USA
| | - Robert Paul Skelton
- South African Environmental Observation NetworkKirstenbosch Botanical Gardens Cape Town South Africa
| | - Kate M. Johnson
- School of Biological Sciences University of Tasmania Hobart TAS Australia
| | - Christopher Lucani
- School of Biological Sciences University of Tasmania Hobart TAS Australia
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49
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Li X, Smith R, Choat B, Tissue DT. Drought resistance of cotton (Gossypium hirsutum) is promoted by early stomatal closure and leaf shedding. FUNCTIONAL PLANT BIOLOGY : FPB 2020; 47:91-98. [PMID: 31825787 DOI: 10.1071/fp19093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 09/06/2019] [Indexed: 05/11/2023]
Abstract
Water relations have been well documented in tree species, but relatively little is known about the hydraulic characteristics of crops. Here, we report on the hydraulic strategy of cotton (Gossypium hirsutum L.). Leaf gas exchange and in vivo embolism formation were monitored simultaneously on plants that were dried down in situ under controlled environment conditions, and xylem vulnerability to embolism of leaves, stems and roots was measured using intact plants. Water potential inducing 50% embolised vessels (P50) in leaves was significantly higher (less negative) than P50 of stems and roots, suggesting that leaves were the most vulnerable organ to embolism. Furthermore, the water potential generating stomatal closure (Pgs) was higher than required to generate embolism formation, and complete stomatal closure always preceded the onset of embolism with declining soil water content. Although protracted drought resulted in massive leaf shedding, stem embolism remained minimal even after ~90% leaf area was lost. Overall, cotton maintained hydraulic integrity during long-term drought stress through early stomatal closure and leaf shedding, thus exhibiting a drought avoidance strategy. Given that water potentials triggering xylem embolism are uncommon under field conditions, cotton is unlikely to experience hydraulic dysfunction except under extreme climates. Results of this study provide physiological evidence for drought resistance in cotton with regard to hydraulics, and may provide guidance in developing irrigation schedules during periods of water shortage.
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Affiliation(s)
- Ximeng Li
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - Renee Smith
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia; and Corresponding author.
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50
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Pratt RB, Castro V, Fickle JC, Jacobsen AL. Embolism resistance of different aged stems of a California oak species (Quercus douglasii): optical and microCT methods differ from the benchtop-dehydration standard. TREE PHYSIOLOGY 2020; 40:5-18. [PMID: 31553460 DOI: 10.1093/treephys/tpz092] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 07/30/2019] [Accepted: 08/15/2019] [Indexed: 06/10/2023]
Abstract
Vulnerability of xylem to embolism is an important trait related to drought resistance of plants. Methods continue to be developed and debated for measuring embolism. We tested three methods (benchtop dehydration/hydraulic, micro-computed tomography (microCT) and optical) for assessing the vulnerability to embolism of a native California oak species (Quercus douglasii Hook. & Arn.), including an analysis of three different stem ages. All three methods were found to significantly differ in their estimates, with a greater resistance to embolism as follows: microCT > optical > hydraulic. Careful testing was conducted for the hydraulic method to evaluate multiple known potential artifacts, and none was found. One-year-old stems were more resistant than older stems using microCT and optical methods, but not hydraulic methods. Divergence between the microCT and optical methods from the standard hydraulic method was consistent with predictions based on known errors when estimating theoretical losses in hydraulic function in both microCT and optical methods. When the goal of a study is to describe or predict losses in hydraulic conductivity, neither the microCT nor optical methods are reliable for accurately constructing vulnerability curves of stems; nevertheless, these methods may be useful if the goal of a study is to identify embolism events irrespective of hydraulic conductivity or hydraulic function.
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Affiliation(s)
- R Brandon Pratt
- Department of Biology, California State University, Bakersfield, 9001 Stockdale Hwy, Bakersfield, CA
| | - Viridiana Castro
- Department of Biology, California State University, Bakersfield, 9001 Stockdale Hwy, Bakersfield, CA
| | - Jaycie C Fickle
- Department of Biology, California State University, Bakersfield, 9001 Stockdale Hwy, Bakersfield, CA
| | - Anna L Jacobsen
- Department of Biology, California State University, Bakersfield, 9001 Stockdale Hwy, Bakersfield, CA
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