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Jacobsen AL, Venturas MD, Hacke UG, Pratt RB. Sap flow through partially embolized xylem vessel networks. PLANT, CELL & ENVIRONMENT 2024. [PMID: 38826042 DOI: 10.1111/pce.14990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 05/16/2024] [Accepted: 05/18/2024] [Indexed: 06/04/2024]
Abstract
Sap is transported through numerous conduits in the xylem of woody plants along the path from the soil to the leaves. When all conduits are functional, vessel lumen diameter is a strong predictor of hydraulic conductivity. As vessels become embolized, sap movement becomes increasingly affected by factors operating at scales beyond individual conduits, creating resistances that result in hydraulic conductivity diverging from diameter-based estimates. These effects include pit resistances, connectivity, path length, network topology, and vessel or sector isolation. The impact of these factors varies with the level and distribution of emboli within the network, and manifest as alterations in the relationship between the number and diameter of embolized vessels with measured declines in hydraulic conductivity across vulnerability to embolism curves. Divergences between measured conductivity and diameter-based estimates reveal functional differences that arise because of species- and tissue-specific vessel network structures. Such divergences are not uniform, and xylem tissues may diverge in different ways and to differing degrees. Plants regularly operate under nonoptimal conditions and contain numerous embolized conduits. Understanding the hydraulic implications of emboli within a network and the function of partially embolized networks are critical gaps in our understanding of plants occurring within natural environments.
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Affiliation(s)
- Anna L Jacobsen
- Department of Biology, California State University, Bakersfield, California, USA
| | - Martin D Venturas
- Departamento de Sistemas y Recursos Naturales, Universidad Politécnica de Madrid, Madrid, Spain
| | - Uwe G Hacke
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
| | - Robert Brandon Pratt
- Department of Biology, California State University, Bakersfield, California, USA
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2
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Tang W, Liu X, Liang X, Liu H, Yu K, He P, McAdam S, Zhao H, Ye Q. Hydraulic vulnerability difference between branches and roots increases with environmental aridity. Oecologia 2024; 205:177-190. [PMID: 38772916 DOI: 10.1007/s00442-024-05562-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 05/01/2024] [Indexed: 05/23/2024]
Abstract
The vulnerability of plant xylem to embolism can be described as the water potential at which xylem conductivity is lost by 50% (P50). According to the traditional hypothesis of hydraulic vulnerability segmentation, the difference in vulnerability to embolism between branches and roots is positive (P50 root-branch > 0). It is not clear whether this occurs broadly across species or how segmentation might vary across aridity gradients. We compiled hydraulic and anatomical datasets from branches and roots across 104 woody species (including new measurements from 10 species) in four biomes to investigate the relationships between P50 root-branch and environmental factors associated with aridity. We found a positive P50 root-branch relationship across species, and evidence that P50 root-branch increases with aridity. Branch xylem hydraulic conductivity transitioned from more efficient (e.g., wider conduit, higher hydraulic conductivity) to safer (e.g., narrower conduit, more negative P50) in response to the increase of aridity, while root xylem hydraulic conductivity remained unchanged across aridity gradients. Our results demonstrate that the hydraulic vulnerability difference between branches and roots is more positive in species from arid regions, largely driven by modifications to branch traits.
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Affiliation(s)
- Weize Tang
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of National Forestry and Grassland Administration on Plant Conservation and Utilization in Southern China, South China Botanical Garden, Chinese Academy of Sciences, No. 723, Xingke Road, Tianhe District, Guangzhou, 510650, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaorong Liu
- Sichuan University of Arts and Science, Tashi Road 519, Dazhou, 635000, China
| | - Xingyun Liang
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of National Forestry and Grassland Administration on Plant Conservation and Utilization in Southern China, South China Botanical Garden, Chinese Academy of Sciences, No. 723, Xingke Road, Tianhe District, Guangzhou, 510650, China
| | - Hui Liu
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of National Forestry and Grassland Administration on Plant Conservation and Utilization in Southern China, South China Botanical Garden, Chinese Academy of Sciences, No. 723, Xingke Road, Tianhe District, Guangzhou, 510650, China
| | - Kailiang Yu
- High Meadows Environmental Institute, Princeton University, Princeton, NJ, USA
| | - Pengcheng He
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of National Forestry and Grassland Administration on Plant Conservation and Utilization in Southern China, South China Botanical Garden, Chinese Academy of Sciences, No. 723, Xingke Road, Tianhe District, Guangzhou, 510650, China
| | - Scott McAdam
- Purdue Center for Plant Biology, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA
| | - Han Zhao
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of National Forestry and Grassland Administration on Plant Conservation and Utilization in Southern China, South China Botanical Garden, Chinese Academy of Sciences, No. 723, Xingke Road, Tianhe District, Guangzhou, 510650, China
| | - Qing Ye
- Guangdong Provincial Key Laboratory of Applied Botany and Key Laboratory of National Forestry and Grassland Administration on Plant Conservation and Utilization in Southern China, South China Botanical Garden, Chinese Academy of Sciences, No. 723, Xingke Road, Tianhe District, Guangzhou, 510650, China.
- College of Life Sciences, Gannan Normal University, Ganzhou, 341000, China.
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3
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Liu YY, Chao L, Li ZG, Ma L, Hu BQ, Zhu SD, Cao KF. Water storage capacity is inversely associated with xylem embolism resistance in tropical karst tree species. TREE PHYSIOLOGY 2024; 44:tpae017. [PMID: 38281245 DOI: 10.1093/treephys/tpae017] [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: 09/15/2023] [Accepted: 01/21/2024] [Indexed: 01/30/2024]
Abstract
Tropical karst habitats are characterized by limited and patchy soil, large rocky outcrops and porous substrates, resulting in high habitat heterogeneity and soil moisture fluctuations. Xylem hydraulic efficiency and safety can determine the drought adaptation and spatial distribution of woody plants growing in karst environments. In this study, we measured sapwood-specific hydraulic conductivity (Ks), vulnerability to embolism, wood density, saturated water content, and vessel and pit anatomical characteristics in the branch stems of 12 evergreen tree species in a tropical karst seasonal rainforest in southwestern China. We aimed to characterize the effects of structural characteristics on hydraulic efficiency and safety. Our results showed that there was no significant correlation between Ks and hydraulic safety across the tropical karst woody species. Ks was correlated with hydraulic vessel diameter (r = 0.80, P < 0.05) and vessel density (r = -0.60, P < 0.05), while the stem water potential at 50 and 88% loss of hydraulic conductivity (P50 and P88) were both significantly correlated with wood density (P < 0.05) and saturated water content (P = 0.052 and P < 0.05, respectively). High stem water storage capacity was associated with low cavitation resistance possibly because of its buffering the moisture fluctuations in karst environments. However, both Ks and P50/P88 were decoupled from the anatomical traits of pit and pit membranes. This may explain the lack of tradeoff between hydraulic safety and efficiency in tropical karst evergreen tree species. Our results suggest that diverse hydraulic trait combination may facilitate species coexistence in karst environments with high spatial heterogeneity.
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Affiliation(s)
- Yan-Yan Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, Guangxi, China
- Key Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Guangxi Key Laboratory of Earth Surface Processes and Intelligent Simulation, Nanning Normal University, Nanning 530001, China
| | - Lin Chao
- Key Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Guangxi Key Laboratory of Earth Surface Processes and Intelligent Simulation, Nanning Normal University, Nanning 530001, China
| | - Zhong-Guo Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, Guangxi, China
- Experimental Center of Tropical Forestry, Chinese Academy of Forestry, Pingxiang 532600, Guangxi, China
| | - Lin Ma
- Key Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Guangxi Key Laboratory of Earth Surface Processes and Intelligent Simulation, Nanning Normal University, Nanning 530001, China
| | - Bao-Qing Hu
- Key Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Guangxi Key Laboratory of Earth Surface Processes and Intelligent Simulation, Nanning Normal University, Nanning 530001, China
| | - Shi-Dan Zhu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, Guangxi, China
| | - Kun-Fang Cao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, Guangxi, China
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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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Chu C, Momayyezi M, Stobbs JA, Soolanayakanahally RY, McElrone AJ, Knipfer T. Drought-induced fiber water release and xylem embolism susceptibility of intact balsam poplar saplings. PHYSIOLOGIA PLANTARUM 2023; 175:e14040. [PMID: 37882281 DOI: 10.1111/ppl.14040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 08/31/2023] [Accepted: 09/27/2023] [Indexed: 10/27/2023]
Abstract
Balsam poplar (Populus balsamifera L.) is a widespread tree species in North America with significant ecological and economic value. However, little is known about the susceptibility of saplings to drought-induced embolism and its link to water release from surrounding xylem fibers. Questions remain regarding localized mechanisms that contribute to the survival of saplings in vivo of this species under drought. Using X-ray micro-computed tomography on intact saplings of genotypes Gillam-5 and Carnduff-9, we found that functional vessels are embedded in a matrix of water-filled fibers under well-watered conditions in both genotypes. However, water-depleted fibers started to appear under moderate drought stress while vessels remained water-filled in both genotypes. Drought-induced xylem embolism susceptibility was comparable between genotypes, and a greater frequency of smaller diameter vessels in GIL-5 did not increase embolism resistance in this genotype. Despite having smaller vessels and a total vessel number that was comparable to CAR-9, stomatal conductance was generally higher in GIL-5 compared to CAR-9. In conclusion, our in vivo data on intact saplings indicate that differences in embolism susceptibility are negligible between GIL-5 and CAR-9, and that fiber water release should be considered as a mechanism that contributes to the maintenance of vessel functional status in saplings of balsam poplar experiencing their first drought event.
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Affiliation(s)
- Cheyenne Chu
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mina Momayyezi
- Department of Viticulture and Enology, University of California, Davis, California, USA
| | | | | | - Andrew J McElrone
- Department of Viticulture and Enology, University of California, Davis, California, USA
- USDA-ARS, Crops Pathology and Genetics Research Unit, Davis, California, USA
| | - Thorsten Knipfer
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
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Yin XH, Hao GY, Sterck F. Ring- and diffuse-porous tree species from a cold temperate forest diverge in stem hydraulic traits, leaf photosynthetic traits, growth rate and altitudinal distribution. TREE PHYSIOLOGY 2023; 43:722-736. [PMID: 36715627 DOI: 10.1093/treephys/tpad008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 01/06/2023] [Accepted: 01/20/2023] [Indexed: 05/13/2023]
Abstract
In cold and humid temperate forests, low temperature, late frost and frequent freeze-thaw cycles are the main factors limiting tree growth and survival. Ring- and diffuse-porous tree species differing in xylem anatomy coexist in these forests, but their divergent adaptations to these factors have been poorly explored. To fill this knowledge gap, we compared four ring-porous and four diffuse-porous tree species from the same temperate forest in Northeast China by quantifying their leaf and stem functional traits, their stem growth rates using tree ring analysis and their resistance to cold represented by upper altitude species distribution borders from survey data. We found that the ring-porous trees were characterized by traits related to more rapid water transport, carbon gain and stem growth rates than those of the diffuse-porous species. Compared with the diffuse-porous species, the ring-porous species had a significantly higher shoot hydraulic conductance (Ks-shoot, 0.52 vs 1.03 kg m-1 s-1 MPa-1), leaf photosynthetic rate (An, 11.28 vs 15.83 μmol m-2 s-1), relative basal area increment (BAIr, 2.28 vs 0.72 cm year-1) and stem biomass increment (M, 0.34 vs 0.09 kg year-1 m-1). However, the observed upper elevational distribution limit of the diffuse-porous species was higher than that of the ring-porous species and was associated with higher values of conservative traits, such as longer leaf life span (R2 = 0.52). Correspondingly, BAIr and M showed significant positive correlations with acquisitive traits such as Ks-shoot (R2 = 0.77) and leaf photosynthetic rate (R2 = 0.73) across the eight species, with the ring-porous species occurring at the fast-acquisitive side of the spectrum and the diffuse-porous species located on the opposite side. The observed contrasts in functional traits between the two species groups improved our understanding of their differences in terms of growth strategies and adaptive capabilities in the cold, humid temperate forests.
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Affiliation(s)
- Xiao-Han Yin
- Key Laboratory of Terrestrial Ecosystem Carbon Neutrality, Shengyang, Liaoning 110016, China
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shengyang, Liaoning 110016, China
- Forest Ecology and Forest Management Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands
| | - Guang-You Hao
- Key Laboratory of Terrestrial Ecosystem Carbon Neutrality, Shengyang, Liaoning 110016, China
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shengyang, Liaoning 110016, China
| | - Frank Sterck
- Forest Ecology and Forest Management Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands
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7
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Isasa E, Link RM, Jansen S, Tezeh FR, Kaack L, Sarmento Cabral J, Schuldt B. Addressing controversies in the xylem embolism resistance-vessel diameter relationship. THE NEW PHYTOLOGIST 2023; 238:283-296. [PMID: 36636783 DOI: 10.1111/nph.18731] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 12/06/2022] [Indexed: 06/17/2023]
Abstract
Although xylem embolism is a key process during drought-induced tree mortality, its relationship to wood anatomy remains debated. While the functional link between bordered pits and embolism resistance is known, there is no direct, mechanistic explanation for the traditional assumption that wider vessels are more vulnerable than narrow ones. We used data from 20 temperate broad-leaved tree species to study the inter- and intraspecific relationship of water potential at 50% loss of conductivity (P50 ) with hydraulically weighted vessel diameter (Dh ) and tested its link to pit membrane thickness (TPM ) and specific conductivity (Ks ) on species level. Embolism-resistant species had thick pit membranes and narrow vessels. While Dh was weakly associated with TPM , the P50 -Dh relationship remained highly significant after accounting for TPM . The interspecific pattern between P50 and Dh was mirrored by a link between P50 and Ks , but there was no evidence for an intraspecific relationship. Our results provide robust evidence for an interspecific P50 -Dh relationship across our species. As a potential cause for the inconsistencies in published P50 -Dh relationships, our analysis suggests differences in the range of trait values covered, and the level of data aggregation (species, tree or sample level) studied.
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Affiliation(s)
- Emilie Isasa
- Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Institute of Biological Sciences, University of Würzburg, Julius-von-Sachs-Platz 3, 97082, Würzburg, Germany
| | - Roman Mathias Link
- Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Institute of Biological Sciences, University of Würzburg, Julius-von-Sachs-Platz 3, 97082, Würzburg, Germany
- Chair of Forest Botany, Institute of Forest Botany and Forest Zoology, Technical University of Dresden, Pienner Str. 7, 01737, Tharandt, Germany
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Fon Robinson Tezeh
- Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Institute of Biological Sciences, University of Würzburg, Julius-von-Sachs-Platz 3, 97082, Würzburg, Germany
| | - Lucian Kaack
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Juliano Sarmento Cabral
- Ecosystem Modeling Group, Center for Computational and Theoretical Biology, University of Würzburg, Klara-Oppenheimer-Weg 32, 97074, Würzburg, Germany
- Biodiversity Modelling and Environmental Change, School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Bernhard Schuldt
- Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Institute of Biological Sciences, University of Würzburg, Julius-von-Sachs-Platz 3, 97082, Würzburg, Germany
- Chair of Forest Botany, Institute of Forest Botany and Forest Zoology, Technical University of Dresden, Pienner Str. 7, 01737, Tharandt, Germany
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8
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Zhang C, Khan A, Duan CY, Cao Y, Wu DD, Hao GY. Xylem hydraulics strongly influence the niche differentiation of tree species along the slope of a river valley in a water-limited area. PLANT, CELL & ENVIRONMENT 2023; 46:106-118. [PMID: 36253806 DOI: 10.1111/pce.14467] [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: 08/22/2022] [Revised: 10/03/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
Xylem hydraulic characteristics govern plant water transport, affecting both drought resistance and photosynthetic gas exchange. Therefore, they play critical roles in determining the adaptation of different species to environments with various water regimes. Here, we tested the hypothesis that variation in xylem traits associated with a trade-off between hydraulic efficiency and safety against drought-induced embolism contributes to niche differentiation of tree species along a sharp water availability gradient on the slope of a unique river valley located in a semi-humid area. We found that tree species showed clear niche differentiation with decreasing water availability from the bottom towards the top of the valley. Tree species occupying different positions, in terms of vertical distribution distance from the bottom of the valley, showed a strong trade-off between xylem water transport efficiency and safety, as evidenced by variations in xylem structural traits at both the tissue and pit levels. This optimized their xylem hydraulics in their respective water regimes. Thus, the trade-off between hydraulic efficiency and safety contributes to clear niche differentiation and, thereby, to the coexistence of tree species in the valley with heterogeneous water availability.
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Affiliation(s)
- Chi Zhang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
- Daqinggou Ecological Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Attaullah Khan
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
- Daqinggou Ecological Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
| | - Chun-Yang Duan
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
- Daqinggou Ecological Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yu Cao
- Institute of Sand Land Control and Utilization, Liaoning Province, Fuxin, China
| | - De-Dong Wu
- Institute of Sand Land Control and Utilization, Liaoning Province, Fuxin, China
| | - Guang-You Hao
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
- Daqinggou Ecological Research Station, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
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9
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Lens F, Gleason SM, Bortolami G, Brodersen C, Delzon S, Jansen S. Functional xylem characteristics associated with drought-induced embolism in angiosperms. THE NEW PHYTOLOGIST 2022; 236:2019-2036. [PMID: 36039697 DOI: 10.1111/nph.18447] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 08/03/2022] [Indexed: 06/15/2023]
Abstract
Hydraulic failure resulting from drought-induced embolism in the xylem of plants is a key determinant of reduced productivity and mortality. Methods to assess this vulnerability are difficult to achieve at scale, leading to alternative metrics and correlations with more easily measured traits. These efforts have led to the longstanding and pervasive assumed mechanistic link between vessel diameter and vulnerability in angiosperms. However, there are at least two problems with this assumption that requires critical re-evaluation: (1) our current understanding of drought-induced embolism does not provide a mechanistic explanation why increased vessel width should lead to greater vulnerability, and (2) the most recent advancements in nanoscale embolism processes suggest that vessel diameter is not a direct driver. Here, we review data from physiological and comparative wood anatomy studies, highlighting the potential anatomical and physicochemical drivers of embolism formation and spread. We then put forward key knowledge gaps, emphasising what is known, unknown and speculation. A meaningful evaluation of the diameter-vulnerability link will require a better mechanistic understanding of the biophysical processes at the nanoscale level that determine embolism formation and spread, which will in turn lead to more accurate predictions of how water transport in plants is affected by drought.
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Affiliation(s)
- Frederic Lens
- Naturalis Biodiversity Center, PO Box 9517, 2300 RA, Leiden, the Netherlands
- Leiden University, Institute of Biology Leiden, Plant Sciences, Sylviusweg 72, 2333 BE, Leiden, the Netherlands
| | - Sean M Gleason
- Water Management and Systems Research Unit, United States Department of Agriculture, Agricultural Research Service, Fort Collins, CO, 80526, USA
| | - Giovanni Bortolami
- Naturalis Biodiversity Center, PO Box 9517, 2300 RA, Leiden, the Netherlands
| | - Craig Brodersen
- School of the Environment, Yale University, New Haven, CT, 06511, USA
| | - Sylvain Delzon
- University of Bordeaux, INRAE, BIOGECO, 33615, Pessac, France
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, D-89081, Ulm, Germany
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10
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Weithmann G, Paligi SS, Schuldt B, Leuschner C. Branch xylem vascular adjustments in European beech in response to decreasing water availability across a precipitation gradient. TREE PHYSIOLOGY 2022; 42:2224-2238. [PMID: 35861677 DOI: 10.1093/treephys/tpac080] [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: 05/11/2021] [Accepted: 07/02/2022] [Indexed: 06/15/2023]
Abstract
Crucial for the climate adaptation of trees is a xylem anatomical structure capable of adjusting to changing water regimes. Although species comparisons across climate zones have demonstrated anatomical change in response to altered water availability and tree height, less is known about the adaptability of tree vascular systems to increasing water deficits at the intraspecific level. Information on the between-population and within-population variability of xylem traits helps assessing a species' ability to cope with climate change. We investigated the variability of wood anatomical and related hydraulic traits in terminal branches of European beech (Fagus sylvatica L.) trees across a precipitation gradient (520-890 mm year-1) and examined the influence of climatic water balance (CWB), soil water capacity (AWC), neighborhood competition (CI), tree height and branch age on these traits. Furthermore, the relationship between xylem anatomical traits and embolism resistance (P50) was tested. Within-population trait variation was larger than between-population variation. Vessel diameter, lumen-to-sapwood area ratio and potential conductivity of terminal branches decreased with decreasing CWB, but these traits were not affected by AWC, whereas vessel density increased with an AWC decrease. In contrast, none of the studied anatomical traits were influenced by variation in tree height (21-34 m) or CI. Branch age was highly variable (2-22 years) despite equal diameter and position in the flow path, suggesting different growth trajectories in the past. Vessel diameter decreased, and vessel density increased, with increasing branch age, reflecting negative annual radial growth trends. Although vessel diameter was not related to P50, vessel grouping index and lumen-to-sapwood area ratio showed a weak, though highly significant, positive relationship to P50. We conclude that the xylem anatomy of terminal tree-top branches in European beech is modified in response to increasing climatic aridity and/or decreasing soil water availability, independent of a tree height effect.
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Affiliation(s)
- Greta Weithmann
- Plant Ecology, Albrecht von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073 Goettingen, Germany
| | - Sharath Shyamappa Paligi
- Plant Ecology, Albrecht von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073 Goettingen, Germany
| | - Bernhard Schuldt
- Plant Ecology, Albrecht von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073 Goettingen, Germany
- Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Institute of Biological Sciences, University of Würzburg, Julius-von-Sachs-Platz, 97082 Würzburg, Germany
| | - Christoph Leuschner
- Plant Ecology, Albrecht von Haller Institute for Plant Sciences, University of Goettingen, Untere Karspüle 2, 37073 Goettingen, Germany
- Centre for Biodiversity and Sustainable Land Use (CBL), University of Goettingen, 37075 Goettingen, Germany
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11
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Johnson DM, Katul G, Domec J. Catastrophic hydraulic failure and tipping points in plants. PLANT, CELL & ENVIRONMENT 2022; 45:2231-2266. [PMID: 35394656 PMCID: PMC9544843 DOI: 10.1111/pce.14327] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 03/14/2022] [Accepted: 03/20/2022] [Indexed: 06/12/2023]
Abstract
Water inside plants forms a continuous chain from water in soils to the water evaporating from leaf surfaces. Failures in this chain result in reduced transpiration and photosynthesis and are caused by soil drying and/or cavitation-induced xylem embolism. Xylem embolism and plant hydraulic failure share several analogies to 'catastrophe theory' in dynamical systems. These catastrophes are often represented in the physiological and ecological literature as tipping points when control variables exogenous (e.g., soil water potential) or endogenous (e.g., leaf water potential) to the plant are allowed to vary on time scales much longer than time scales associated with cavitation events. Here, plant hydraulics viewed from the perspective of catastrophes at multiple spatial scales is considered with attention to bubble expansion within a xylem conduit, organ-scale vulnerability to embolism, and whole-plant biomass as a proxy for transpiration and hydraulic function. The hydraulic safety-efficiency tradeoff, hydraulic segmentation and maximum plant transpiration are examined using this framework. Underlying mechanisms for hydraulic failure at fine scales such as pit membranes and cell-wall mechanics, intermediate scales such as xylem network properties and at larger scales such as soil-tree hydraulic pathways are discussed. Understudied areas in plant hydraulics are also flagged where progress is urgently needed.
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Affiliation(s)
- Daniel M. Johnson
- Warnell School of Forestry and Natural ResourcesUniversity of GeorgiaAthensGeorgiaUSA
| | - Gabriel Katul
- Department of Civil and Environmental EngineeringDuke UniversityDurhamNorth CarolinaUSA
- Nicholas School of the EnvironmentDuke UniversityDurhamNorth CarolinaUSA
| | - Jean‐Christophe Domec
- Nicholas School of the EnvironmentDuke UniversityDurhamNorth CarolinaUSA
- Department of ForestryBordeaux Sciences Agro, UMR INRAE‐ISPA 1391GradignanFrance
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12
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Hietz P, Rungwattana K, Scheffknecht S, George JP. Effects of Provenance, Growing Site, and Growth on Quercus robur Wood Anatomy and Density in a 12-Year-Old Provenance Trial. FRONTIERS IN PLANT SCIENCE 2022; 13:795941. [PMID: 35574121 PMCID: PMC9100569 DOI: 10.3389/fpls.2022.795941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 03/22/2022] [Indexed: 06/15/2023]
Abstract
Vessels are responsible for an efficient and safe water transport in angiosperm xylem. Whereas large vessels efficiently conduct the bulk of water, small vessels might be important under drought stress or after winter when large vessels are embolized. Wood anatomy can adjust to the environment by plastic adaptation, but is also modified by genetic selection, which can be driven by climate or other factors. To distinguish between plastic and genetic components on wood anatomy, we used a Quercus robur trial where trees from ten Central European provenances were planted in three locations in Austria along a rainfall gradient. Because wood anatomy also adjusts to tree size and in ring-porous species, the vessel size depends on the amount of latewood and thereby ring width, we included tree size and ring width in the analysis. We found that the trees' provenance had a significant effect on average vessel area (VA), theoretical specific hydraulic conductivity (Ks), and the vessel fraction (VF), but correlations with annual rainfall of provenances were at best weak. The trial site had a strong effect on growth (ring width, RW), which increased from the driest to the wettest site and wood density (WD), which increased from wet to dry sites. Significant site x provenance interactions were seen only for WD. Surprisingly, the drier site had higher VA, higher VF, and higher Ks. This, however, is mainly a result of greater RW and thus a greater proportion of latewood in the wetter forest. The average size of vessels > 70 μm diameter increased with rainfall. We argue that Ks, which is measured per cross-sectional area, is not an ideal parameter to compare the capacity of ring-porous trees to supply leaves with water. Small vessels (<70 μm) on average contributed only 1.4% to Ks, and we found no evidence that their number or size was adaptive to aridity. RW and tree size had strong effect on all vessel parameters, likely via the greater proportion of latewood in wide rings. This should be accounted for when searching for wood anatomical adaptations to the environment.
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Affiliation(s)
- Peter Hietz
- Department of Integrative Biology and Biodiversity Research, Institute of Botany, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Kanin Rungwattana
- Department of Integrative Biology and Biodiversity Research, Institute of Botany, University of Natural Resources and Life Sciences, Vienna, Austria
- Department of Botany, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Susanne Scheffknecht
- Department of Integrative Biology and Biodiversity Research, Institute of Botany, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Jan-Peter George
- Department of Forest Genetics, Federal Research and Training Centre for Forests, Natural Hazards and Landscape, Vienna, Austria
- Faculty of Science and Technology, University of Tartu, Tartu, Estonia
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13
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Fontes CG, Pinto‐Ledezma J, Jacobsen AL, Pratt RB, Cavender‐Bares J. Adaptive variation among oaks in wood anatomical properties is shaped by climate of origin and shows limited plasticity across environments. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13964] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Clarissa G. Fontes
- Department of Ecology, Evolution and Behavior University of Minnesota Saint Paul MN USA
| | - Jesús Pinto‐Ledezma
- Department of Ecology, Evolution and Behavior University of Minnesota Saint Paul MN USA
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14
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Suissa JS, Friedman WE. From cells to stems: the effects of primary vascular construction on drought-induced embolism in fern rhizomes. THE NEW PHYTOLOGIST 2021; 232:2238-2253. [PMID: 34273190 DOI: 10.1111/nph.17629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
While a considerable amount of data exists on the link between xylem construction and hydraulic function, few studies have focused on resistance to drought-induced embolism of primary vasculature in herbaceous plants. Ferns rely entirely on primary xylem and display a remarkable diversity of vascular construction in their rhizomes, making them an ideal group in which to examine hydraulic structure-function relationships. New optical methods allowed us to measure vulnerability to embolism in rhizomes, which are notoriously difficult to work with. We investigated five fern species based on their diverse xylem traits at the cellular, histological, and architectural levels. To link below- and above-ground hydraulics, we then measured leaf-stem vulnerability segmentation. Overall, rhizome vulnerability to embolism was correlated most strongly with cellular but not histological or architectural traits. Interestingly, at P6-12 , species with increased architectural dissection were actually more vulnerable to embolism, suggesting different hydraulic dynamics at low compared to high percent embolism. Importantly, leaves fully embolize before stems reach P88 , suggesting strong vulnerability segmentation. This is the first study to explore the functional implications of primary vascular construction in fern rhizomes and leaf-stem vulnerability segmentation. Strong segmentation suggests that leaves protect perennial rhizomes against severe drought stress and hydraulically induced mortality.
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Affiliation(s)
- Jacob S Suissa
- The Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- The Arnold Arboretum of Harvard University, Boston, MA, 02131, USA
| | - William E Friedman
- The Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02138, USA
- The Arnold Arboretum of Harvard University, Boston, MA, 02131, USA
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15
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Lemaire C, Quilichini Y, Brunel-Michac N, Santini J, Berti L, Cartailler J, Conchon P, Badel É, Herbette S. Plasticity of the xylem vulnerability to embolism in Populus tremula x alba relies on pit quantity properties rather than on pit structure. TREE PHYSIOLOGY 2021; 41:1384-1399. [PMID: 33554260 DOI: 10.1093/treephys/tpab018] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 01/22/2021] [Indexed: 06/12/2023]
Abstract
Knowledge on variations of drought resistance traits are needed to predict the potential of trees to acclimate to coming severe drought events. Xylem vulnerability to embolism is a key parameter related to such droughts, and its phenotypic variability relies mainly on environmental plasticity. We investigated the structural determinants controlling the plasticity of vulnerability to embolism, focusing on the key elements involved in the air bubble entry in vessels, especially the intervessel pits. Poplar saplings (Populus tremula x alba (Aiton) Sm., 1804) grown in contrasted water availability or light exposure exhibited differences in the vulnerability to embolism (P50) in a range of 0.76 MPa. We then characterized the structural changes in features related to pit quantity and pit structure, from the pit ultrastructure to the organization of xylem vessels, using different microscopy techniques (transmission electron microscopy, scanning electron microscopy, light microscopy). A multispectral combination of X-ray microtomography and light microscopy analysis allowed measuring the vulnerability of each single vessel and testing some of the relationships between structural traits and vulnerability to embolism inside the xylem. The pit ultrastructure did not change, whereas the vessel dimensions increased with the vulnerability to embolism and the grouping index and fraction of intervessel cell wall both decreased with the vulnerability to embolism. These findings hold when comparing between trees or between the vessels inside the xylem of an individual tree. These results evidenced that plasticity of vulnerability to embolism in hybrid poplar occurs through changes in the pit quantity properties such as pit area and vessel grouping rather than changes on the pit structure.
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Affiliation(s)
- Cédric Lemaire
- Université Clermont Auvergne, INRAE, PIAF, F-63000 Clermont-Ferrand, France
| | - Yann Quilichini
- CNRS-Università di Corsica, UMR 6134 SPE, 20250 Corti, France
| | | | - Jérémie Santini
- CNRS-Università di Corsica, UMR 6134 SPE, 20250 Corti, France
| | - Liliane Berti
- CNRS-Università di Corsica, UMR 6134 SPE, 20250 Corti, France
| | - Julien Cartailler
- Université Clermont Auvergne, INRAE, PIAF, F-63000 Clermont-Ferrand, France
| | - Pierre Conchon
- Université Clermont Auvergne, INRAE, PIAF, F-63000 Clermont-Ferrand, France
| | - Éric Badel
- Université Clermont Auvergne, INRAE, PIAF, F-63000 Clermont-Ferrand, France
| | - Stéphane Herbette
- Université Clermont Auvergne, INRAE, PIAF, F-63000 Clermont-Ferrand, France
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16
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Fanton AC, Brodersen C. Hydraulic consequences of enzymatic breakdown of grapevine pit membranes. PLANT PHYSIOLOGY 2021; 186:1919-1931. [PMID: 33905519 PMCID: PMC8331172 DOI: 10.1093/plphys/kiab191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 04/01/2021] [Indexed: 06/12/2023]
Abstract
Xylella fastidiosa (Xf) is the xylem-dwelling bacterial agent associated with Pierce's disease (PD), which leads to significant declines in productivity in agriculturally important species like grapevine (Vitis vinifera). Xf spreads through the xylem network by digesting the pit membranes (PMs) between adjacent vessels, thereby potentially changing the hydraulic properties of the stem. However, the effects of Xf on water transport vary depending on the plant host and the infection stage, presenting diverse outcomes. Here, we investigated the effects of polygalacturonase, an enzyme known to be secreted by Xf when it produces biofilm on the PM surface, on stem hydraulic conductivity, and PM integrity. Experiments were performed on six grapevine genotypes with varying levels of PD resistance, with the expectation that PM resistance to degradation by polygalacturonase may play a role in PD resistance. Our objective was to study a single component of this pathosystem in isolation to better understand the mechanisms behind reported changes in hydraulics, thereby excluding the biological response of the plant to the presence of Xf in the vascular system. PM damage only occurred in stems perfused with polygalacturonase. Although the damaged PM area was small (2%-9% of the total pit aperture area), membrane digestion led to significant changes in the median air-seeding thresholds, and most importantly, shifted frequency distribution. Finally, enzyme perfusion also resulted in a universal reduction in stem hydraulic conductivity, suggesting the development of tyloses may not be the only contributing factor to reduced hydraulic conductivity in infected grapevine.
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Affiliation(s)
- Ana Clara Fanton
- School of the Environment, Yale University, New Haven, Connecticut 06511, USA
| | - Craig Brodersen
- School of the Environment, Yale University, New Haven, Connecticut 06511, USA
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17
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Jupa R, Krabičková D, Plichta R, Mayr S, Gloser V. Do angiosperm tree species adjust intervessel lateral contact in response to soil drought? PHYSIOLOGIA PLANTARUM 2021; 172:2048-2058. [PMID: 33876443 DOI: 10.1111/ppl.13435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 04/15/2021] [Indexed: 06/12/2023]
Abstract
During soil drought (i.e. limited soil water availability to plants), woody species may adjust the structure of their vessel network to improve their resistance against future soil drought stress. Impacts of soil drought on intervessel lateral contact remain poorly understood despite of its significance to xylem transport efficiency and safety. Here, we analysed drought-induced modifications in xylem structures of temperate angiosperm trees with a focus on intervessel lateral contact. Anatomical analyses were performed both in stems of seedlings cultivated under different substrate water availability and annual rings of mature individuals developed during years of low and high soil drought intensities. In response to limited water availability, a decrease in vessel diameter (up to -20%) and simultaneous increase in vessel density (up to +60%) were observed both in seedlings and mature trees. Conversely, there were only small and inconsistent drought-induced changes in intervessel contact frequency and intervessel contact fraction (typically up to ±15%) observed across species, indicating that intervessel lateral contact is a conservative trait. The small adjustments in intervessel lateral contacts were primarily driven by changes in the contact frequencies between neighbouring vessels (i.e. vessel grouping) rather than by changes in proportions of shared cell walls. Our results demonstrate that angiosperm tree species, despite remarkable adjustments in vessel dimensions and densities upon soil drought, exhibit surprisingly invariant intervessel lateral contact architecture.
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Affiliation(s)
- Radek Jupa
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
- Department of Forest Botany, Dendrology and Geobiocenology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Brno, Czech Republic
| | - Dita Krabičková
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Roman Plichta
- Department of Forest Botany, Dendrology and Geobiocenology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Brno, Czech Republic
| | - Stefan Mayr
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Vít Gloser
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
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18
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Mrad A, Johnson DM, Love DM, Domec JC. The roles of conduit redundancy and connectivity in xylem hydraulic functions. THE NEW PHYTOLOGIST 2021; 231:996-1007. [PMID: 33908055 DOI: 10.1111/nph.17429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 04/20/2021] [Indexed: 06/12/2023]
Abstract
Wood anatomical traits shape a xylem segment's hydraulic efficiency and resistance to embolism spread due to declining water potential. It has been known for decades that variations in conduit connectivity play a role in altering xylem hydraulics. However, evaluating the precise effect of conduit connectivity has been elusive. The objective here is to establish an analytical linkage between conduit connectivity and grouping and tissue-scale hydraulics. It is hypothesized that an increase in conduit connectivity brings improved resistance to embolism spread due to increased hydraulic pathway redundancy. However, an increase in conduit connectivity could also reduce resistance due to increased speed of embolism spread with respect to pressure. We elaborate on this trade-off using graph theory, percolation theory and computational modeling of xylem. The results are validated using anatomical measurements of Acer branch xylem. Considering only species with vessels, increases in connectivity improve resistance to embolism spread without negatively affecting hydraulic conductivity. The often measured grouping index fails to capture the totality of the effect of conduit connectivity on xylem hydraulics. Variations in xylem network characteristics, such as conduit connectivity, might explain why hypothesized trends among woody species, such as the 'safety-efficiency' trade-off hypothesis, are weaker than expected.
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Affiliation(s)
- Assaad Mrad
- Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA
- Department of Civil and Environmental Engineering, University of California, Irvine, CA, 92697, USA
- Department of Engineering, Wake Forest University, Winston-Salem, NC, 27101, USA
| | - Daniel M Johnson
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA
| | - David M Love
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA
| | - Jean-Christophe Domec
- Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA
- Bordeaux Sciences Agro, UMR 1391 INRA-ISPA, Gradignan Cedex, 33175, France
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19
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Oyanoghafo OO, O’ Brien C, Choat B, Tissue D, Rymer PD. Vulnerability to xylem cavitation of Hakea species (Proteaceae) from a range of biomes and life histories predicted by climatic niche. ANNALS OF BOTANY 2021; 127:909-918. [PMID: 33606015 PMCID: PMC8225280 DOI: 10.1093/aob/mcab020] [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: 10/27/2020] [Accepted: 02/17/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND AND AIMS Extreme drought conditions across the globe are impacting biodiversity, with serious implications for the persistence of native species. However, quantitative data on physiological tolerance are not available for diverse flora to inform conservation management. We quantified physiological resistance to cavitation in the diverse Hakea genus (Proteaceae) to test predictions based on climatic origin, life history and functional traits. METHODS We sampled terminal branches of replicate plants of 16 species in a common garden. Xylem cavitation was induced in branches under varying water potentials (tension) in a centrifuge, and the tension generating 50 % loss of conductivity (stem P50) was characterized as a metric for cavitation resistance. The same branches were used to estimate plant functional traits, including wood density, specific leaf area and Huber value (sap flow area to leaf area ratio). KEY RESULTS There was significant variation in stem P50 among species, which was negatively associated with the species climate origin (rainfall and aridity). Cavitation resistance did not differ among life histories; however, a drought avoidance strategy with terete leaf form and greater Huber value may be important for species to colonize and persist in the arid biome. CONCLUSIONS This study highlights climate (rainfall and aridity), rather than life history and functional traits, as the key predictor of variation in cavitation resistance (stem P50). Rainfall for species origin was the best predictor of cavitation resistance, explaining variation in stem P50, which appears to be a major determinant of species distribution. This study also indicates that stem P50 is an adaptive trait, genetically determined, and hence reliable and robust for predicting species vulnerability to climate change. Our findings will contribute to future prediction of species vulnerability to drought and adaptive management under climate change.
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Affiliation(s)
- Osazee O Oyanoghafo
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2751,Australia
- Department of Plant Biology and Biotechnology, Faculty of Life Sciences, University of Benin, Benin City, Nigeria
| | - Corey O’ Brien
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2751,Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2751,Australia
| | - David Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2751,Australia
| | - Paul D Rymer
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales 2751,Australia
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20
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MacMillan P, Teixeira G, Lopes CM, Monteiro A. The role of grapevine leaf morphoanatomical traits in determining capacity for coping with abiotic stresses: a review. CIÊNCIA E TÉCNICA VITIVINÍCOLA 2021. [DOI: 10.1051/ctv/ctv2021360175] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Worldwide, there are thousands of Vitis vinifera grape cultivars used for wine production, creating a large morphological, anatomical, physiological and molecular diversity that needs to be further characterised and explored, with a focus on their capacity to withstand biotic and abiotic stresses. This knowledge can then be used to select better adapted genotypes in order to help face the challenges of the expected climate changes in the near future. It will also assist grape growers in choosing the most suitable cultivar(s) for each terroir; with adaptation to drought and heat stresses being a fundamental characteristic. The leaf blade of grapevines is the most exposed organ to abiotic stresses, therefore its study regarding the tolerance to water and heat stress is becoming particularly important, mainly in Mediterranean viticulture. This review focuses on grapevine leaf morphoanatomy - leaf blade form, leaf epidermis characteristics (cuticle, indumentum, pavement cells and stomata) and anatomy of mesophyll - and their adaptation to abiotic stresses. V. vinifera xylem architecture and its adaptation capacity when the grapevine is subjected to water stress is also highlighted since grapevines have been observed to exhibit a large variability in responses to water availability. The hydraulic properties of the petiole, shoot and trunk are also reviewed. Summarising, this paper reviews recent advances related to the adaptation of grapevine leaf morphoanatomical features and hydraulic architecture to abiotic stresses, mainly water and heat stress, induced primarily by an ever-changing global climate.
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21
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Kaack L, Weber M, Isasa E, Karimi Z, Li S, Pereira L, Trabi CL, Zhang Y, Schenk HJ, Schuldt B, Schmidt V, Jansen S. Pore constrictions in intervessel pit membranes provide a mechanistic explanation for xylem embolism resistance in angiosperms. THE NEW PHYTOLOGIST 2021; 230:1829-1843. [PMID: 33595117 DOI: 10.1111/nph.17282] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 02/09/2021] [Indexed: 05/27/2023]
Abstract
Embolism spreading in angiosperm xylem occurs via mesoporous pit membranes between vessels. Here, we investigate how the size of pore constrictions in pit membranes is related to pit membrane thickness and embolism resistance. Pit membranes were modelled as multiple layers to investigate how pit membrane thickness and the number of intervessel pits per vessel determine pore constriction sizes, the probability of encountering large pores, and embolism resistance. These estimations were complemented by measurements of pit membrane thickness, embolism resistance, and number of intervessel pits per vessel in stem xylem (n = 31, 31 and 20 species, respectively). The modelled constriction sizes in pit membranes decreased with increasing membrane thickness, explaining the measured relationship between pit membrane thickness and embolism resistance. The number of pits per vessel affected constriction size and embolism resistance much less than pit membrane thickness. Moreover, a strong relationship between modelled and measured embolism resistance was observed. Pore constrictions provide a mechanistic explanation for why pit membrane thickness determines embolism resistance, which suggests that hydraulic safety can be uncoupled from hydraulic efficiency. Although embolism spreading remains puzzling and encompasses more than pore constriction sizes, angiosperms are unlikely to have leaky pit membranes, which enables tensile transport of water.
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Affiliation(s)
- Lucian Kaack
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, Ulm, D-89081, Germany
| | - Matthias Weber
- Institute of Stochastics, Ulm University, Helmholtzstraße 18, Ulm, D-89069, Germany
| | - Emilie Isasa
- Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Institute for Biological Sciences, University of Würzburg, Julius-von-Sachs-Platz 3, Würzburg, D-97082, Germany
| | - Zohreh Karimi
- Department of Biology, Faculty of Sciences, Golestan University, Shahid Beheshti St., Gorgan, 15759-49138, Iran
| | - Shan Li
- Department of Wood Anatomy and Utilization, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing, 100091, China
| | - Luciano Pereira
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, Ulm, D-89081, Germany
| | - Christophe L Trabi
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, Ulm, D-89081, Germany
| | - Ya Zhang
- College of Life Sciences, Anhui Normal University, Beijingdong Road 1, Wuhu, 241000, China
| | - H Jochen Schenk
- Department of Biological Science, California State University Fullerton, Fullerton, CA, 92834-6850, USA
| | - Bernhard Schuldt
- Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Institute for Biological Sciences, University of Würzburg, Julius-von-Sachs-Platz 3, Würzburg, D-97082, Germany
| | - Volker Schmidt
- Institute of Stochastics, Ulm University, Helmholtzstraße 18, Ulm, D-89069, Germany
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, Ulm, D-89081, Germany
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22
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Wason J, Bouda M, Lee EF, McElrone AJ, Phillips RJ, Shackel KA, Matthews MA, Brodersen C. Xylem network connectivity and embolism spread in grapevine(Vitis vinifera L.). PLANT PHYSIOLOGY 2021; 186:373-387. [PMID: 33576825 PMCID: PMC8154096 DOI: 10.1093/plphys/kiab045] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 01/17/2021] [Indexed: 05/20/2023]
Abstract
Xylem networks are vulnerable to the formation and spread of gas embolisms that reduce water transport. Embolisms spread through interconduit pits, but the three-dimensional (3D) complexity and scale of xylem networks means that the functional implications of intervessel connections are not well understood. Here, xylem networks of grapevine (Vitis vinifera L.) were reconstructed from 3D high-resolution X-ray micro-computed tomography (microCT) images. Xylem network performance was then modeled to simulate loss of hydraulic conductivity under increasingly negative xylem sap pressure simulating drought stress conditions. We also considered the sensitivity of xylem network performance to changes in key network parameters. We found that the mean pit area per intervessel connection was constant across 10 networks from three, 1.5-m stem segments, but short (0.5 cm) segments fail to capture complete network connectivity. Simulations showed that network organization imparted additional resistance to embolism spread beyond the air-seeding threshold of pit membranes. Xylem network vulnerability to embolism spread was most sensitive to variation in the number and location of vessels that were initially embolized and pit membrane vulnerability. Our results show that xylem network organization can increase stem resistance to embolism spread by 40% (0.66 MPa) and challenge the notion that a single embolism can spread rapidly throughout an entire xylem network.
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Affiliation(s)
- Jay Wason
- School of Forest Resources, University of Maine, Orono, Maine 04469
- School of the Environment, Yale University, New Haven, CT 06520
| | - Martin Bouda
- Institute of Botany, Czech Academy of Sciences, Průhonice, Czechia
| | - Eric F Lee
- Department of Engineering Sciences, Clackamas Community College, Oregon City, Oregon 97045
| | - Andrew J McElrone
- Department of Viticulture and Enology, University of California Davis, Davis, California
- Crops Pathology and Genetics Research Unit, USDA-ARS, Davis, California
| | - Ronald J Phillips
- Department of Chemical Engineering, University of California Davis, Davis, California
| | - Kenneth A Shackel
- Department of Plant Science, University of California Davis, Davis, California
| | - Mark A Matthews
- Department of Viticulture and Enology, University of California Davis, Davis, California
| | - Craig Brodersen
- School of the Environment, Yale University, New Haven, CT 06520
- Author for communication:
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Levionnois S, Jansen S, Wandji RT, Beauchêne J, Ziegler C, Coste S, Stahl C, Delzon S, Authier L, Heuret P. Linking drought-induced xylem embolism resistance to wood anatomical traits in Neotropical trees. THE NEW PHYTOLOGIST 2021; 229:1453-1466. [PMID: 32964439 DOI: 10.1111/nph.16942] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 09/04/2020] [Indexed: 05/27/2023]
Abstract
Drought-induced xylem embolism is considered to be one of the main factors driving mortality in woody plants worldwide. Although several structure-functional mechanisms have been tested to understand the anatomical determinants of embolism resistance, there is a need to study this topic by integrating anatomical data for many species. We combined optical, laser, and transmission electron microscopy to investigate vessel diameter, vessel grouping, and pit membrane ultrastructure for 26 tropical rainforest tree species across three major clades (magnoliids, rosiids, and asteriids). We then related these anatomical observations to previously published data on drought-induced embolism resistance, with phylogenetic analyses. Vessel diameter, vessel grouping, and pit membrane ultrastructure were all predictive of xylem embolism resistance, but with weak predictive power. While pit membrane thickness was a predictive trait when vestured pits were taken into account, the pit membrane diameter-to-thickness ratio suggests a strong importance of the deflection resistance of the pit membrane. However, phylogenetic analyses weakly support adaptive coevolution. Our results emphasize the functional significance of pit membranes for air-seeding in tropical rainforest trees, highlighting also the need to study their mechanical properties due to the link between embolism resistance and pit membrane diameter-to-thickness ratio. Finding support for adaptive coevolution also remains challenging.
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Affiliation(s)
- Sébastien Levionnois
- UMR EcoFoG, AgroParisTech, CIRAD, CNRS, INRAE, Université des Antilles, Université de Guyane, Kourou, 97310, France
- UMR AMAP, Université de Montpellier, CIRAD, CNRS, INRAE, IRD, Montpellier, 34000, France
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Ulm, D-89081, Germany
| | - Ruth Tchana Wandji
- UMR EcoFoG, AgroParisTech, CIRAD, CNRS, INRAE, Université des Antilles, Université de Guyane, Kourou, 97310, France
| | - Jacques Beauchêne
- UMR EcoFoG, AgroParisTech, CIRAD, CNRS, INRAE, Université des Antilles, Université de Guyane, Kourou, 97310, France
| | - Camille Ziegler
- UMR EcoFoG, AgroParisTech, CIRAD, CNRS, INRAE, Université des Antilles, Université de Guyane, Kourou, 97310, France
- AgroParisTech, UMR Silva, INRAE, Université de Lorraine, Nancy, F-54000, 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
| | - Sylvain Delzon
- UMR BIOGECO, INRAE, Université de Bordeaux, Pessac, 33615, France
| | - Louise Authier
- 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
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24
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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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25
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Albuquerque C, Scoffoni C, Brodersen CR, Buckley TN, Sack L, McElrone AJ. Coordinated decline of leaf hydraulic and stomatal conductances under drought is not linked to leaf xylem embolism for different grapevine cultivars. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:7286-7300. [PMID: 33306796 DOI: 10.1093/jxb/eraa392] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 10/27/2020] [Indexed: 06/12/2023]
Abstract
Drought decreases water transport capacity of leaves and limits gas exchange, which involves reduced leaf leaf hydraulic conductance (Kleaf) in both the xylem and outside-xylem pathways. Some literature suggests that grapevines are hyper-susceptible to drought-induced xylem embolism. We combined Kleaf and gas exchange measurements, micro-computed tomography of intact leaves, and spatially explicit modeling of the outside-xylem pathways to evaluate the role of vein embolism and Kleaf in the responses of two different grapevine cultivars to drought. Cabernet Sauvignon and Chardonnay exhibited similar vulnerabilities of Kleaf and gs to dehydration, decreasing substantially prior to leaf xylem embolism. Kleaf and gs decreased by 80% for both cultivars by Ψ leaf approximately -0.7 MPa and -1.2 MPa, respectively, while leaf xylem embolism initiated around Ψ leaf = -1.25 MPa in the midribs and little to no embolism was detected in minor veins even under severe dehydration for both cultivars. Modeling results indicated that reduced membrane permeability associated with a Casparian-like band in the leaf vein bundle sheath would explain declines in Kleaf of both cultivars. We conclude that during moderate water stress, changes in the outside-xylem pathways, rather than xylem embolism, are responsible for reduced Kleaf and gs. Understanding this mechanism could help to ensure adequate carbon capture and crop performance under drought.
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Affiliation(s)
- Caetano Albuquerque
- Department of Viticulture and Enology, University of California, Davis, 595 Hilgard Lane, Davis, CA, USA
| | - Christine Scoffoni
- Department of Biological Sciences, California State University, Los Angeles, 5151 State University Drive, Los Angeles, CA, USA
| | - Craig R Brodersen
- School of the Environment, Yale University, 195 Prospect Street, New Haven, CT, USA
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, One Shields Avenue, Davis, CA, USA
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, USA
| | - Andrew J McElrone
- Department of Viticulture and Enology, University of California, Davis, 595 Hilgard Lane, Davis, CA, USA
- USDA-Agricultural Research Service, Davis, CA, USA
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26
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Wang DR, Venturas MD, Mackay DS, Hunsaker DJ, Thorp KR, Gore MA, Pauli D. Use of hydraulic traits for modeling genotype-specific acclimation in cotton under drought. THE NEW PHYTOLOGIST 2020; 228:898-909. [PMID: 32557592 PMCID: PMC7586954 DOI: 10.1111/nph.16751] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 06/07/2020] [Indexed: 06/11/2023]
Abstract
Understanding the genetic and physiological basis of abiotic stress tolerance under field conditions is key to varietal crop improvement in the face of climate variability. Here, we investigate dynamic physiological responses to water stress in silico and their relationships to genotypic variation in hydraulic traits of cotton (Gossypium hirsutum), an economically important species for renewable textile fiber production. In conjunction with an ecophysiological process-based model, heterogeneous data (plant hydraulic traits, spatially-distributed soil texture, soil water content and canopy temperature) were used to examine hydraulic characteristics of cotton, evaluate their consequences on whole plant performance under drought, and explore potential genotype × environment effects. Cotton was found to have R-shaped hydraulic vulnerability curves (VCs), which were consistent under drought stress initiated at flowering. Stem VCs, expressed as percent loss of conductivity, differed across genotypes, whereas root VCs did not. Simulation results demonstrated how plant physiological stress can depend on the interaction between soil properties and irrigation management, which in turn affect genotypic rankings of transpiration in a time-dependent manner. Our study shows how a process-based modeling framework can be used to link genotypic variation in hydraulic traits to differential acclimating behaviors under drought.
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Affiliation(s)
- Diane R. Wang
- Department of GeographyUniversity at BuffaloBuffaloNY14261USA
- Present address:
Department of AgronomyPurdue UniversityWest LafayetteIN47907USA
| | | | - D. Scott Mackay
- Department of GeographyUniversity at BuffaloBuffaloNY14261USA
| | | | - Kelly R. Thorp
- US Arid‐Land Agricultural Research CenterMaricopaAZ37860USA
| | - Michael A. Gore
- Plant Breeding and Genetics SectionSchool of Integrative Plant ScienceCornell UniversityIthacaNY14853USA
| | - Duke Pauli
- School of Plant SciencesUniversity of ArizonaTucsonAZ85721USA
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27
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Zhao H, Jiang Z, Ma J, Cai J. What causes the differences in cavitation resistance of two shrubs? Wood anatomical explanations and reliability testing of vulnerability curves. PHYSIOLOGIA PLANTARUM 2020; 169:156-168. [PMID: 31828790 DOI: 10.1111/ppl.13059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 12/09/2019] [Accepted: 12/09/2019] [Indexed: 06/10/2023]
Abstract
Relationships between xylem anatomical traits and cavitation resistance have always been a major content of plant hydraulics. To know how plants cope with drought, it is extremely important to acquire detailed knowledge about xylem anatomical traits and assess the cavitation resistance accurately. This study aims to increase our knowledge in the methods determining cavitation resistance and xylem anatomical traits. We selected a semi-ring-porous species, Hippophae rhamnoides L., and a diffuse-porous species, Corylus heterophylla F., to clarify the reasons for the difference in cavitation resistance based on detailed xylem anatomical traits and reliable vulnerability curves (VCs). Both Cavitron and bench dehydration (BD) were used to construct VCs. Xylem anatomical traits, including pit membrane ultrastructure of these two species, were determined. The VCs obtained by the two different techniques were of different types for H. rhamnoides, its Cavitron VCs might be unreliable because of open-vessel artifacts. On the basis of BD VCs, H. rhamnoides showed higher cavitation resistance than C. heterophylla, and this is attributed to its low vessel connectivity as well as non-porous and thicker pit membranes.
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Affiliation(s)
- Han Zhao
- College of Forestry, Northwest A&F University, Yangling, 712100, China
| | - Zaimin Jiang
- College of Life Sciences, Northwest A&F University, Yangling, 712100, China
| | - Jin Ma
- College of Forestry, Northwest A&F University, Yangling, 712100, China
| | - Jing Cai
- College of Forestry, Northwest A&F University, Yangling, 712100, China
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28
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Janssen TAJ, Hölttä T, Fleischer K, Naudts K, Dolman H. Wood allocation trade-offs between fiber wall, fiber lumen, and axial parenchyma drive drought resistance in neotropical trees. PLANT, CELL & ENVIRONMENT 2020; 43:965-980. [PMID: 31760666 PMCID: PMC7155043 DOI: 10.1111/pce.13687] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/14/2019] [Accepted: 11/18/2019] [Indexed: 05/25/2023]
Abstract
Functional relationships between wood density and measures of xylem hydraulic safety and efficiency are ambiguous, especially in wet tropical forests. In this meta-analysis, we move beyond wood density per se and identify relationships between xylem allocated to fibers, parenchyma, and vessels and measures of hydraulic safety and efficiency. We analyzed published data of xylem traits, hydraulic properties and measures of drought resistance from neotropical tree species retrieved from 346 sources. We found that xylem volume allocation to fiber walls increases embolism resistance, but at the expense of specific conductivity and sapwood capacitance. Xylem volume investment in fiber lumen increases capacitance, while investment in axial parenchyma is associated with higher specific conductivity. Dominant tree taxa from wet forests prioritize xylem allocation to axial parenchyma at the expense of fiber walls, resulting in a low embolism resistance for a given wood density and a high vulnerability to drought-induced mortality. We conclude that strong trade-offs between xylem allocation to fiber walls, fiber lumen, and axial parenchyma drive drought resistance in neotropical trees. Moreover, the benefits of xylem allocation to axial parenchyma in wet tropical trees might not outweigh the consequential low embolism resistance under more frequent and severe droughts in a changing climate.
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Affiliation(s)
- Thomas A. J. Janssen
- Department of Earth Sciences, Cluster Earth and ClimateVrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Teemu Hölttä
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and ForestryUniversity of HelsinkiHelsinkiFinland
| | - Katrin Fleischer
- Land Surface‐Atmosphere InteractionsTechnical University of MunichFreisingGermany
| | - Kim Naudts
- Department of Earth Sciences, Cluster Earth and ClimateVrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Han Dolman
- Department of Earth Sciences, Cluster Earth and ClimateVrije Universiteit AmsterdamAmsterdamThe Netherlands
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29
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Li S, Wang J, Yin Y, Li X, Deng L, Jiang X, Chen Z, Li Y. Investigating Effects of Bordered Pit Membrane Morphology and Properties on Plant Xylem Hydraulic Functions-A Case Study from 3D Reconstruction and Microflow Modelling of Pit Membranes in Angiosperm Xylem. PLANTS (BASEL, SWITZERLAND) 2020; 9:E231. [PMID: 32054100 PMCID: PMC7076482 DOI: 10.3390/plants9020231] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/18/2020] [Accepted: 02/08/2020] [Indexed: 01/12/2023]
Abstract
Pit membranes in between neighboring conduits of xylem play a crucial role in plant water transport. In this review, the morphological characteristics, chemical composition and mechanical properties of bordered pit membranes were summarized and linked with their functional roles in xylem hydraulics. The trade-off between xylem hydraulic efficiency and safety was closely related with morphology and properties of pit membranes, and xylem embolism resistance was also determined by the pit membrane morphology and properties. Besides, to further investigate the effects of bordered pit membranes morphology and properties on plant xylem hydraulic functions, here we modelled three-dimensional structure of bordered pit membranes by applying a deposition technique. Based on reconstructed 3D pit membrane structures, a virtual fibril network was generated to model the microflow pattern across inter-vessel pit membranes. Moreover, the mechanical behavior of intervessel pit membranes was estimated from a single microfibril's mechanical property. Pit membranes morphology varied among different angiosperm and gymnosperm species. Our modelling work suggested that larger pores of pit membranes do not necessarily contribute to major flow rate across pit membranes; instead, the obstructed degree of flow pathway across the pit membranes plays a more important role. Our work provides useful information for studying the mechanism of microfluid flow transport across pit membranes and also sheds light on investigating the response of pit membranes both at normal and stressed conditions, thus improving our understanding on functional roles of pit membranes in xylem hydraulic function. Further work could be done to study the morphological and mechanical response of bordered pit membranes under different dehydrated conditions, as well as the related microflow behavior, based on our constructed model.
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Affiliation(s)
- Shan Li
- Department of Wood Anatomy and Utilization, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China; (S.L.); (J.W.); (Y.Y.); (L.D.); (X.J.)
- Wood Collections (WOODPEDIA), Chinese Academy of Forestry, Beijing 100091, China
| | - Jie Wang
- Department of Wood Anatomy and Utilization, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China; (S.L.); (J.W.); (Y.Y.); (L.D.); (X.J.)
- Wood Collections (WOODPEDIA), Chinese Academy of Forestry, Beijing 100091, China
| | - Yafang Yin
- Department of Wood Anatomy and Utilization, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China; (S.L.); (J.W.); (Y.Y.); (L.D.); (X.J.)
- Wood Collections (WOODPEDIA), Chinese Academy of Forestry, Beijing 100091, China
| | - Xin Li
- College of Forestry, Beijing Forestry University, Beijing 100083, China;
| | - Liping Deng
- Department of Wood Anatomy and Utilization, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China; (S.L.); (J.W.); (Y.Y.); (L.D.); (X.J.)
- International Center for Bamboo and Rattan, Beijing 100102, China
| | - Xiaomei Jiang
- Department of Wood Anatomy and Utilization, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China; (S.L.); (J.W.); (Y.Y.); (L.D.); (X.J.)
- Wood Collections (WOODPEDIA), Chinese Academy of Forestry, Beijing 100091, China
| | - Zhicheng Chen
- Institute of New Forestry Technology, Chinese Academy of Forestry, Beijing 100083, China;
| | - Yujun Li
- School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710072, China
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30
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Bernard C, Compagnoni A, Salguero‐Gómez R. Testing Finch's hypothesis: The role of organismal modularity on the escape from actuarial senescence. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13486] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Aldo Compagnoni
- Martin Luther University Halle‐Wittenberg German Centre for Integrative Biodiversity Research Leipzig Germany
| | - Roberto Salguero‐Gómez
- Department of Zoology University of Oxford Oxford UK
- Centre for Biodiversity and Conservation Science University of Queensland St. Lucia QLD Australia
- Evolutionary Demography laboratory Max Plank Institute for Demographic Research Rostock Germany
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31
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Zhang Y, Carmesin C, Kaack L, Klepsch MM, Kotowska M, Matei T, Schenk HJ, Weber M, Walther P, Schmidt V, Jansen S. High porosity with tiny pore constrictions and unbending pathways characterize the 3D structure of intervessel pit membranes in angiosperm xylem. PLANT, CELL & ENVIRONMENT 2020; 43:116-130. [PMID: 31595539 DOI: 10.1111/pce.13654] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 09/10/2019] [Accepted: 09/10/2019] [Indexed: 05/29/2023]
Abstract
Pit membranes between xylem vessels play a major role in angiosperm water transport. Yet, their three-dimensional (3D) structure as fibrous porous media remains unknown, largely due to technical challenges and sample preparation artefacts. Here, we applied a modelling approach based on thickness measurements of fresh and fully shrunken pit membranes of seven species. Pore constrictions were also investigated visually by perfusing fresh material with colloidal gold particles of known sizes. Based on a shrinkage model, fresh pit membranes showed tiny pore constrictions of ca. 20 nm, but a very high porosity (i.e. pore volume fraction) of on average 0.81. Perfusion experiments showed similar pore constrictions in fresh samples, well below 50 nm based on transmission electron microscopy. Drying caused a 50% shrinkage of pit membranes, resulting in much smaller pore constrictions. These findings suggest that pit membranes represent a mesoporous medium, with the pore space characterized by multiple constrictions. Constrictions are much smaller than previously assumed, but the pore volume is large and highly interconnected. Pores do not form highly tortuous, bent, or zigzagging pathways. These insights provide a novel view on pit membranes, which is essential to develop a mechanistic, 3D understanding of air-seeding through this porous medium.
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Affiliation(s)
- Ya Zhang
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
- College of Life Sciences, Anhui Normal University, Beijingdong Road 1, 241000, Wuhu, Anhui, China
| | - Cora Carmesin
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Lucian Kaack
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Matthias M Klepsch
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Martyna Kotowska
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
- Albrecht-von-Haller Institute for Plant Sciences, University of Göttingen, Untere Karspüle 2, 37073, Göttingen, Germany
| | - Tabea Matei
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - H Jochen Schenk
- Department of Biological Science, California State University Fullerton, 800 N. State College Blvd, CA, 92831-3599, Fullerton, USA
| | - Matthias Weber
- Institute of Stochastics, Ulm University, Helmholtzstraße 18, 89069, Ulm, Germany
| | - Paul Walther
- Central Facility for Electron Microscopy, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Volker Schmidt
- Institute of Stochastics, Ulm University, Helmholtzstraße 18, 89069, Ulm, Germany
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
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32
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López R, Nolf M, Duursma RA, Badel E, Flavel RJ, Cochard H, Choat B. Mitigating the open vessel artefact in centrifuge-based measurement of embolism resistance. TREE PHYSIOLOGY 2019; 39:143-155. [PMID: 30085232 DOI: 10.1093/treephys/tpy083] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/03/2018] [Indexed: 06/08/2023]
Abstract
Centrifuge-based techniques to assess xylem vulnerability to embolism are increasingly being used, although we are yet to reach a consensus on the nature and extent of artefactual embolism observed in some angiosperm species. In particular, there is disagreement over whether these artefacts influence both the spin (Cavitron) and static versions of the centrifuge technique equally. We tested two methods for inducing embolism: bench dehydration and centrifugation. We used three methods to measure the resulting loss of conductivity: gravimetric flow measured in bench-dehydrated and centrifuged samples (static centrifuge), in situ flow measured under tension during spinning in the centrifuge (Cavitron) and direct imaging using X-ray computed microtomography (microCT) observations in stems of two species of Hakea that differ in vessel length. Both centrifuge techniques were prone to artefactual embolism in samples with maximum vessel length longer than, or similar to, the centrifuge rotor diameter. Observations with microCT indicated that this artefactual embolism occurred in the outermost portions of samples. The artefact was largely eliminated if flow was measured in an excised central part of the segment in the static centrifuge or starting measurements with the Cavitron at pressures lower than the threshold of embolism formation in open vessels. The simulations of loss of conductivity in centrifuged samples with a new model, CAVITOPEN, confirmed that the impact of open vessels on the vulnerability to embolism curve was higher when vessels were long, samples short and when embolism is formed in open vessels at less negative pressures. This model also offers a robust and quantitative tool to test and correct for artefactual embolism at low xylem tensions.
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Affiliation(s)
- Rosana López
- Université Clermont Auvergne, INRA, PIAF, 5, chemin de Beaulieu, Clermont-Ferrand, France
- Sistemas y Recursos Naturales, Universidad Politécnica de Madrid, C/ José Antonio Novais 10, Madrid, Spain
| | - Markus Nolf
- Hawkesbury Institute for the Environment, Western Sydney University, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW, Australia
| | - Remko A Duursma
- Hawkesbury Institute for the Environment, Western Sydney University, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW, Australia
| | - Eric Badel
- Université Clermont Auvergne, INRA, PIAF, 5, chemin de Beaulieu, Clermont-Ferrand, France
| | - Richard J Flavel
- School of Environmental and Rural Science, University of New England, Elm Avenue, 2351 Armidale, NSW, Australia
| | - Hervé Cochard
- Université Clermont Auvergne, INRA, PIAF, 5, chemin de Beaulieu, Clermont-Ferrand, France
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW, Australia
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Mrad A, Domec JC, Huang CW, Lens F, Katul G. A network model links wood anatomy to xylem tissue hydraulic behaviour and vulnerability to cavitation. PLANT, CELL & ENVIRONMENT 2018; 41:2718-2730. [PMID: 30071137 DOI: 10.1111/pce.13415] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 07/13/2018] [Accepted: 07/25/2018] [Indexed: 05/06/2023]
Abstract
Plant xylem response to drought is routinely represented by a vulnerability curve (VC). Despite the significance of VCs, the connection between anatomy and tissue-level hydraulic response to drought remains a subject of inquiry. We present a numerical model of water flow in flowering plant xylem that combines current knowledge on diffuse-porous anatomy and embolism spread to explore this connection. The model produces xylem networks and uses different parameterizations of intervessel connection vulnerability to embolism spread: the Young-Laplace equation and pit membrane stretching. Its purpose is upscaling processes occurring on the microscopic length scales, such as embolism propagation through pit membranes, to obtain tissue-scale hydraulics. The terminal branch VC of Acer glabrum was successfully reproduced relying only on real observations of xylem tissue anatomy. A sensitivity analysis shows that hydraulic performance and VC shape and location along the water tension axis are heavily dependent on anatomy. The main result is that the linkage between pit-scale and vessel-scale anatomical characters, along with xylem network topology, affects VCs significantly. This work underscores the importance of stepping up research related to the three-dimensional network structure of xylem tissues. The proposed model's versatility makes it an important tool to explore similar future questions.
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Affiliation(s)
- Assaad Mrad
- Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA
| | - Jean-Christophe Domec
- Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA
- Bordeaux Sciences Agro, UMR 1391 INRA-ISPA, 33175, Gradignan Cedex, France
| | - Cheng-Wei Huang
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131-0001
| | - Frederic Lens
- Naturalis Biodiversity Center, Leiden University, P.O. Box 9517, 2300 RA Leiden, The Netherlands
| | - Gabriel Katul
- Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA
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Li F, McCulloh KA, Sun S, Bao W. Linking leaf hydraulic properties, photosynthetic rates, and leaf lifespan in xerophytic species: a test of global hypotheses. AMERICAN JOURNAL OF BOTANY 2018; 105:1858-1868. [PMID: 30449045 DOI: 10.1002/ajb2.1185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 08/20/2018] [Indexed: 06/09/2023]
Abstract
PREMISE OF THE STUDY Leaf venation and its hierarchal traits are crucial to the hydraulic and mechanical properties of leaves, reflecting plant life-history strategies. However, there is an extremely limited understanding of how variation in leaf hydraulics affects the leaf economic spectrum (LES) or whether venation correlates more strongly with hydraulic conductance or biomechanical support among hierarchal orders. METHODS We examined correlations of leaf hydraulics, indicated by vein density, conduit diameter, and stomatal density with light-saturated photosynthetic rates, leaf lifespan (LLS), and leaf morpho-anatomical traits of 39 xerophytic species grown in a common garden. KEY RESULTS We found positive relationships between light-saturated, area-based photosynthetic rates, and vein densities, regardless of vein orders. Densities of leaf veins had positive correlations with stomatal density. We also found positive relationships between LLS and vein densities. Leaf area was negatively correlated with the density of major veins but not with minor veins. Most anatomical traits were not related to vein densities. CONCLUSIONS We developed a network diagram of the correlations among leaf hydraulics and leaf economics, which suggests functional trade-offs between hydraulic costs and lifetime carbon gain. Leaf hydraulics efficiency and carbon assimilation were coupled across species. Vein construction costs directly coordinated with the LLS. Our findings indicate that hierarchal orders of leaf veins did not differ in the strength of their correlations between hydraulic conductance and biomechanical support. These findings clarify how leaf hydraulics contributes to the LES and provide new insight into life-history strategies of these xerophytic species.
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Affiliation(s)
- Fanglan Li
- Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China, 610041
| | | | - Sujing Sun
- Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China, 610041
| | - Weikai Bao
- Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China, 610041
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Knipfer T, Barrios-Masias FH, Cuneo IF, Bouda M, Albuquerque CP, Brodersen CR, Kluepfel DA, McElrone AJ. Variations in xylem embolism susceptibility under drought between intact saplings of three walnut species. TREE PHYSIOLOGY 2018; 38:1180-1192. [PMID: 29850910 DOI: 10.1093/treephys/tpy049] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 05/16/2018] [Indexed: 06/08/2023]
Abstract
A germplasm collection containing varied Juglans genotypes holds potential to improve drought resistance of plant materials for commercial production. We used X-ray computed microtomography to evaluate stem xylem embolism susceptibility/repair in relation to vessel anatomical features (size, arrangement, connectivity and pit characteristics) in 2-year-old saplings of three Juglans species. In vivo analysis revealed interspecific variations in embolism susceptibility among Juglans microcarpa, J. hindsii (both native to arid habitats) and J. ailantifolia (native to mesic habitats). Stem xylem of J. microcarpa was more resistant to drought-induced embolism as compared with J. hindsii and J. ailantifolia (differences in embolism susceptibility among older and current year xylem were not detected in any species). Variations in most vessel anatomical traits were negligible among the three species; however, we detected substantial interspecific differences in intervessel pit characteristics. As compared with J. hindsii and J. ailantifolia, low embolism susceptibility in J. microcarpa was associated with smaller pit size in larger diameter vessels, a smaller area of the shared vessel wall occupied by pits, lower pit frequency and no changes in pit characteristics as vessel diameters increased. Changes in amount of embolized vessels following 40 days of re-watering were minor in intact saplings of all three species highlighting that an embolism repair mechanism did not contribute to drought recovery. In conclusion, our data indicate that interspecific variations in drought-induced embolism susceptibility are associated with species-specific pit characteristics, and these traits may provide a future target for breeding efforts aimed at selecting walnut germplasm with improved drought resistance.
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Affiliation(s)
- Thorsten Knipfer
- Department of Viticulture & Enology, University of California, Davis, CA, USA
| | | | - Italo F Cuneo
- Department of Viticulture & Enology, University of California, Davis, CA, USA
| | - Martin Bouda
- School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA
| | | | - Craig R Brodersen
- School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA
| | - Daniel A Kluepfel
- USDA-ARS, Crops Pathology and Genetics Research Unit, Davis, CA, USA
| | - Andrew J McElrone
- Department of Viticulture & Enology, University of California, Davis, CA, USA
- USDA-ARS, Crops Pathology and Genetics Research Unit, Davis, CA, USA
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36
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Allario T, Tixier A, Awad H, Lemaire C, Brunel N, Badel E, Barigah TS, Julien JL, Peyret P, Mellerowicz EJ, Cochard H, Herbette S. PtxtPME1 and homogalacturonans influence xylem hydraulic properties in poplar. PHYSIOLOGIA PLANTARUM 2018; 163:502-515. [PMID: 29412468 DOI: 10.1111/ppl.12702] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 01/15/2018] [Accepted: 01/31/2018] [Indexed: 06/08/2023]
Abstract
While the xylem hydraulic properties, such as vulnerability to cavitation (VC), are of paramount importance in drought resistance, their genetic determinants remain unexplored. There is evidence that pectins and their methylation pattern are involved, but the detail of their involvement and the corresponding genes need to be clarified. We analyzed the hydraulic properties of the 35S::PME1 transgenic aspen that ectopically under- or over-express a xylem-abundant pectin methyl esterase, PtxtPME1. We also produced and analyzed 4CL1::PGII transgenic poplars expressing a fungal polygalacturonase, AnPGII, under the control of the Ptxa4CL1 promoter that is active in the developing xylem after xylem cell expansion. Both the 35S::PME1 under- and over-expressing aspen lines developed xylem with lower-specific hydraulic conductivity and lower VC, while the 4CL1::PGII plants developed xylem with a higher VC. These xylem hydraulic changes were associated with modifications in xylem structure or in intervessel pit structure that can result in changes in mechanical behavior of the pit membrane. This study shows that homogalacturonans and their methylation pattern influence xylem hydraulic properties, through its effect on xylem cell expansion and on intervessel pit properties and it show a role for PtxtPME1 in the xylem hydraulic properties.
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Affiliation(s)
- Thierry Allario
- UCA, INRA, PIAF, 63000, Clermont-Ferrand, France
- UCA, EA 4678 CIDAM, 63000, Clermont-Ferrand, France
| | - Aude Tixier
- UCA, INRA, PIAF, 63000, Clermont-Ferrand, France
| | - Hosam Awad
- Agriculture and Botany Department, Faculty of Agriculture, Menoufia University, Shebin El-Kom, Egypt
| | | | | | - Eric Badel
- UCA, INRA, PIAF, 63000, Clermont-Ferrand, France
| | | | | | | | - Ewa J Mellerowicz
- Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 901 83, Umeå, Sweden
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Link RM, Schuldt B, Choat B, Jansen S, Cobb AR. Maximum-likelihood estimation of xylem vessel length distributions. J Theor Biol 2018; 455:329-341. [PMID: 30063923 DOI: 10.1016/j.jtbi.2018.07.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 07/26/2018] [Accepted: 07/27/2018] [Indexed: 10/28/2022]
Abstract
Vessel length is an important functional trait for plant hydraulics, because it determines the ratio of flow resistances posed by lumen and pit membranes and hence controls xylem hydraulic efficiency. The most commonly applied methods to estimate vessel lengths are based on the injection of silicon or paint into cut-off stem segments. The number of stained vessels in a series of cross-sections in increasing distance from the injection point is then counted. The resulting infusion profiles are used to estimate the vessel length distribution using one of several statistical algorithms. However, the basis of these algorithms has not been systematically analysed using probability theory. We derive a general mathematical expression for the expected shape of the infusion profile for a given vessel length distribution, provide analytic solutions for five candidate distributions (exponential, Erlang(2), gamma, Weibull, and log-normal), and present maximum likelihood estimators for the parameters of these distributions including implementations in R based on two potential sampling schemes (counting all injected vessels or counting the injected and empty vessels in a random subset of each cross-section). We then explore the performance of these estimators relative to other methods with Monte Carlo experiments. Our analysis demonstrates that most published methods estimate the conditional length distribution of vessels that cross an injection point, which is a size-biased version of the overall length distribution in the stem. We show the mathematical relationship between these distributions and provide methods to estimate either of them. According to our simulation experiments, vessel length distribution was best described by the more flexible models, especially the Weibull distribution. In simulations, the estimators were able to recover the parameters of the vessel length distribution if its functional form was known, achieving an overlap of 90% or more between the true and predicted length distribution when counting no more than 500 injected vessels in 10 cross-sections. This sample size nowadays can easily be reached with the help of automated image analysis.
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Affiliation(s)
- Roman M Link
- Plant Ecology, Albrecht von Haller Institute of Plant Sciences, University of Göttingen, Göttingen 37073, Germany; University of Würzburg, Julius-von-Sachs-Institute of Biological Sciences, Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Platz 3, Würzburg 97082, Germany.
| | - Bernhard Schuldt
- Plant Ecology, Albrecht von Haller Institute of Plant Sciences, University of Göttingen, Göttingen 37073, Germany; University of Würzburg, Julius-von-Sachs-Institute of Biological Sciences, Ecophysiology and Vegetation Ecology, Julius-von-Sachs-Platz 3, Würzburg 97082, Germany.
| | - Brendan Choat
- Hawkesbury Institute for the Environment, University of Western Sydney, Richmond, New South Wales, Australia.
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Ulm 89081, Germany.
| | - Alexander R Cobb
- Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
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Yin XH, Sterck F, Hao GY. Divergent hydraulic strategies to cope with freezing in co-occurring temperate tree species with special reference to root and stem pressure generation. THE NEW PHYTOLOGIST 2018; 219:530-541. [PMID: 29682759 DOI: 10.1111/nph.15170] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/18/2018] [Indexed: 05/23/2023]
Abstract
Some temperate tree species mitigate the negative impacts of frost-induced xylem cavitation by restoring impaired hydraulic function via positive pressures, and may therefore be more resistant to frost fatigue (the phenomenon that post-freezing xylem becomes more susceptible to hydraulic dysfunction) than nonpressure-generating species. We test this hypothesis and investigate underlying anatomical/physiological mechanisms. Using a common garden experiment, we studied key hydraulic traits and detailed xylem anatomical characteristics of 18 sympatric tree species. These species belong to three functional groups, that is, one generating both root and stem pressures (RSP), one generating only root pressure (RP), and one unable to generate such pressures (NP). The three functional groups diverged substantially in hydraulic efficiency, resistance to drought-induced cavitation, and frost fatigue resistance. Most notably, RSP and RP were more resistant to frost fatigue than NP, but this was at the cost of reduced hydraulic conductivity for RSP and reduced resistance to drought-induced cavitation for RP. Our results show that, in environments with strong frost stress: these groups diverge in hydraulic functioning following multiple trade-offs between hydraulic efficiency, resistance to drought and resistance to frost fatigue; and how differences in anatomical characteristics drive such divergence across species.
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Affiliation(s)
- Xiao-Han Yin
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Frank Sterck
- Forest Ecology and Forest Management Group, Wageningen University, PO Box 47, 6700 AA, Wageningen, the Netherlands
| | - Guang-You Hao
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
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Sevanto S, Ryan M, Dickman LT, Derome D, Patera A, Defraeye T, Pangle RE, Hudson PJ, Pockman WT. Is desiccation tolerance and avoidance reflected in xylem and phloem anatomy of two coexisting arid-zone coniferous trees? PLANT, CELL & ENVIRONMENT 2018; 41:1551-1564. [PMID: 29569276 DOI: 10.1111/pce.13198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 02/28/2018] [Accepted: 03/06/2018] [Indexed: 06/08/2023]
Abstract
Plants close their stomata during drought to avoid excessive water loss, but species differ in respect to the drought severity at which stomata close. The stomatal closure point is related to xylem anatomy and vulnerability to embolism, but it also has implications for phloem transport and possibly phloem anatomy to allow sugar transport at low water potentials. Desiccation-tolerant plants that close their stomata at severe drought should have smaller xylem conduits and/or fewer and smaller interconduit pits to reduce vulnerability to embolism but more phloem tissue and larger phloem conduits compared with plants that avoid desiccation. These anatomical differences could be expected to increase in response to long-term reduction in precipitation. To test these hypotheses, we used tridimensional synchroton X-ray microtomograph and light microscope imaging of combined xylem and phloem tissues of 2 coniferous species: one-seed juniper (Juniperus monosperma) and piñon pine (Pinus edulis) subjected to precipitation manipulation treatments. These species show different xylem vulnerability to embolism, contrasting desiccation tolerance, and stomatal closure points. Our results support the hypothesis that desiccation tolerant plants require higher phloem transport capacity than desiccation avoiding plants, but this can be gained through various anatomical adaptations in addition to changing conduit or tissue size.
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Affiliation(s)
- Sanna Sevanto
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Bikini Atoll Road MS J535, Los Alamos, NM, 87545, USA
| | - Max Ryan
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Bikini Atoll Road MS J535, Los Alamos, NM, 87545, USA
| | - L Turin Dickman
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Bikini Atoll Road MS J535, Los Alamos, NM, 87545, USA
| | - Dominique Derome
- Laboratory for Multiscale Studies in Building Physics, Swiss Federal Laboratories for Material Science and Technology (Empa), Ueberlandstrasse 129, 8600, Duebendorf, Switzerland
| | - Alessandra Patera
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen, Switzerland
- Centre d'Imagerie BioMedicale, Ecole Polytechnique Federale de Lausanne, 1015, Lausanne, Switzerland
| | - Thijs Defraeye
- Laboratory for Multiscale Studies in Building Physics, Swiss Federal Laboratories for Material Science and Technology (Empa), Ueberlandstrasse 129, 8600, Duebendorf, Switzerland
- Chair of Building Physics, ETH Zurich, Stefano-Franscini-Platz 5, 8093, Zurich, Switzerland
| | - Robert E Pangle
- Department of Biology, University of New Mexico, Castetter Hall 1480, Yale Boulevard NE, Albuquerque, NM, 87131, USA
| | - Patrick J Hudson
- Department of Biology, University of New Mexico, Castetter Hall 1480, Yale Boulevard NE, Albuquerque, NM, 87131, USA
| | - William T Pockman
- Department of Biology, University of New Mexico, Castetter Hall 1480, Yale Boulevard NE, Albuquerque, NM, 87131, USA
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40
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Wason JW, Anstreicher KS, Stephansky N, Huggett BA, Brodersen CR. Hydraulic safety margins and air-seeding thresholds in roots, trunks, branches and petioles of four northern hardwood trees. THE NEW PHYTOLOGIST 2018; 219:77-88. [PMID: 29663388 DOI: 10.1111/nph.15135] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/28/2018] [Indexed: 05/23/2023]
Abstract
During drought, xylem sap pressures can approach or exceed critical thresholds where gas embolisms form and propagate through the xylem network, leading to systemic hydraulic dysfunction. The vulnerability segmentation hypothesis (VSH) predicts that low-investment organs (e.g. leaf petioles) should be more vulnerable to embolism spread compared to high-investment, perennial organs (e.g. trunks, stems), as a means of mitigating embolism spread and excessive negative pressures in the perennial organs. We tested this hypothesis by measuring air-seeding thresholds using the single-vessel air-injection method and calculating hydraulic safety margins in four northern hardwood tree species of the northeastern United States, in both saplings and canopy height trees, and at five points along the soil-plant-atmosphere continuum. Acer rubrum was the most resistant to air-seeding and generally supported the VSH. However, Fagus grandifolia, Fraxinus americana and Quercus rubra showed little to no variation in air-seeding thresholds across organ types within each species. Leaf-petiole xylem operated at water potentials close to or exceeding their hydraulic safety margins in all species, whereas roots, trunks and stems of A. rubrum, F. grandifolia and Q. rubra operated within their safety margins, even during the third-driest summer in the last 100 yr.
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Affiliation(s)
- Jay W Wason
- School of Forestry & Environmental Studies, Yale University, New Haven, CT, 06511, USA
| | | | | | - Brett A Huggett
- Department of Biology, Bates College, Lewiston, ME, 04240, USA
| | - Craig R Brodersen
- School of Forestry & Environmental Studies, Yale University, New Haven, CT, 06511, USA
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De Baerdemaeker NJF, Hias N, Van den Bulcke J, Keulemans W, Steppe K. The effect of polyploidization on tree hydraulic functioning. AMERICAN JOURNAL OF BOTANY 2018; 105:161-171. [PMID: 29570227 DOI: 10.1002/ajb2.1032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 12/11/2017] [Indexed: 05/14/2023]
Abstract
PREMISE OF THE STUDY Recent research has highlighted the importance of living tissue in wood. Polyploidization can impact amounts and arrangements of living cells in wood, potentially leading to increased drought tolerance. Tetraploid variants were created from the apple cultivar Malus ×domestica 'Gala' (Gala-4x), and their vulnerability to drought-induced cavitation and their hydraulic capacitance were compared to those of their diploid predecessors (Gala-2x). Assuming a positive correlation between polyploidy and drought tolerance, we hypothesized lower vulnerability and higher capacitance for the tetraploid. METHODS Vulnerability to drought-induced cavitation and the hydraulic capacitance were quantified through acoustic emission and continuous weighing of shoots during a bench-top dehydration experiment. To underpin the hydraulic trait results, anatomical variables such as vessel area, conduit diameter, cell wall reinforcement, and ray and vessel-associated parenchyma were measured. KEY RESULTS Vulnerability to drought-induced cavitation was intrinsically equal for both ploidy variants, but Gala-4x proved to be more vulnerable than Gala-2x during the early phase of desiccation as was indicated by its significantly lower air entry value. Higher change in water content of the leafy shoot, higher amount of parenchyma, and larger vessel area and size resulted in a significantly higher hydraulic capacitance and efficiency for Gala-4x compared to Gala-2x. CONCLUSIONS Both ploidy variants were typified as highly sensitive to drought-induced cavitation, with no significant difference in their overall drought vulnerability. But, when water deficit is short and moderate, Gala-4x may delay a drought-induced decrease in performance by trading hydraulic safety for increased release of capacitively stored water from living tissue.
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Affiliation(s)
- Niels J F De Baerdemaeker
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000, Ghent, Belgium
| | - Niek Hias
- Laboratory for Fruit Breeding and Biotechnology, Division of Crop Biotechnics, Katholieke Universiteit (KU) Leuven, Willem de Croylaan 42, B-3001, Heverlee, Belgium
| | - Jan Van den Bulcke
- Laboratory of Wood Technology, Department of Environment, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000, Ghent, Belgium
| | - Wannes Keulemans
- Laboratory for Fruit Breeding and Biotechnology, Division of Crop Biotechnics, Katholieke Universiteit (KU) Leuven, Willem de Croylaan 42, B-3001, Heverlee, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000, Ghent, Belgium
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Ooeda H, Terashima I, Taneda H. Intra-specific trends of lumen and wall resistivities of vessels within the stem xylem vary among three woody plants. TREE PHYSIOLOGY 2018; 38:223-231. [PMID: 29036681 DOI: 10.1093/treephys/tpx114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Accepted: 08/21/2017] [Indexed: 06/07/2023]
Abstract
Water flow through xylem vessels encounters hydraulic resistance when passing through the vessel lumen and end wall. Comparative studies have reported that lumen and end wall resistivities co-limit water flow through stem xylem in several angiosperm woody species that have vessels of different average diameter and length. This study examined the intra-specific relationship between the lumen and end wall resistivities (Rlumen and Rwall) for vessels within the stem xylem using three deciduous angiosperm woody species found in temperate forest. Morus australis Poir. and Acer rufinerve Siebold et Zucc. are early- and late-successional species, and Vitis coignetiae Pulliat ex Planch is a woody liana. According to the Hagen-Poiseuille equation, Rlumen is proportional to the fourth power of vessel diameter (D), whereas vessel length (L) and inter-vessel pit area (Apit) determine Rwall. To estimate Rlumen and Rwall, the scaling relationships between the L and D and between Apit and D were measured. The scaling exponents between L and D were 1.47, 3.19 and 2.86 for A. rufinerve, M. australis and V. coignetiae, respectively, whereas those between Apit and D were 0.242, 2.11 and 2.68, respectively. Unlike the inter-specific relationships, the wall resistivity fraction (Rwall/(Rlumen + Rwall)) within xylem changed depending on D. In M. australis and V. coignetiae, this fraction decreased with increasing D, while in A. rufinerve, it increased with D. Vessels with a high wall resistivity fraction have high Rwall and total resistivity but are expected to have low susceptibility to xylem cavitation due to a small cumulative Apit. In contrast, vessels with a low wall resistivity fraction have low Rwall and total resistivity but high susceptibility to xylem cavitation. Because the wall resistivity fraction varies with D, the stem xylem contains vessels with different hydraulic efficiencies and safety to xylem cavitation. These features produce differences in the hydraulic properties of plants with different life forms.
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Affiliation(s)
- Hiroki Ooeda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Simplex Inc., 1-23-1, Toranomon, Minato-ku, Tokyo 105-6319, Japan
| | - Ichiro Terashima
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Haruhiko Taneda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Johnson D, Eckart P, Alsamadisi N, Noble H, Martin C, Spicer R. Polar auxin transport is implicated in vessel differentiation and spatial patterning during secondary growth in Populus. AMERICAN JOURNAL OF BOTANY 2018; 105:186-196. [PMID: 29578291 DOI: 10.1002/ajb2.1035] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 01/24/2018] [Indexed: 06/08/2023]
Abstract
PREMISE OF THE STUDY Dimensions and spatial distribution of vessels are critically important features of woody stems, allowing for adaptation to different environments through their effects on hydraulic efficiency and vulnerability to embolism. Although our understanding of vessel development is poor, basipetal transport of auxin through the cambial zone may play an important role. METHODS Stems of Populus tremula ×alba were treated with the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) in a longitudinal strip along the length of the lower stem. Vessel lumen diameter, circularity, and length; xylem growth; tension wood area; and hydraulic conductivity before and after a high pressure flush were determined on both NPA-treated and control plants. KEY RESULTS NPA-treated stems formed aberrant vessels that were short, small in diameter, highly clustered, and angular in cross section, whereas xylem formed on the untreated side of the stem contained typical vessels that were similar to those of controls. NPA-treated stems had reduced specific conductivity relative to controls, but this difference was eliminated by the high-pressure flush. The control treatment (lanolin + dimethyl sulfoxide) reduced xylem growth and increased tension wood formation, but never produced the aberrant vessel patterning seen in NPA-treated stems. CONCLUSIONS These results are consistent with a model of vessel development in which basipetal polar auxin transport through the xylem-side cambial derivatives is required for proper expansion and patterning of vessels and demonstrate that reduced auxin transport can produce stems with altered stem hydraulic properties.
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Affiliation(s)
- Dan Johnson
- Department of Botany, Connecticut College, New London, CT 06320, USA
| | - Phoebe Eckart
- Department of Botany, Connecticut College, New London, CT 06320, USA
| | - Noah Alsamadisi
- Department of Botany, Connecticut College, New London, CT 06320, USA
| | | | - Celia Martin
- Department of Biology, Connecticut College, New London, CT 06320, USA
| | - Rachel Spicer
- Department of Botany, Connecticut College, New London, CT 06320, USA
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44
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Abstract
Mathematical models of fluid flow thorough plant stems permit quantitative assessment of plant ecology using anatomy alone, allowing extinct and extant plants to be measured against one another. Through this process, a series of patterns and observations about plant ecology and evolution can be made. First, many plants evolved high rates of water transport through the evolution of a diverse suite of anatomical adaptations over the last four hundred million years. Second, adaptations to increase hydraulic supply to leaves tend to precede, in evolutionary time, adaptations to increase the safety margin of plant water transport. Third, anatomical breakthroughs in water transport function tend to occur in step with ecological breakthroughs, including the appearance of leaves during the Devonian, the evolution of high leaf areas in early seed plants during the Carboniferous, and the early radiation of flowering plants during the Cretaceous. Quantitative assessment of plant function not only opens up the plant fossil record to ecological comparison, but also provides data that can be used to model fluxes and dynamics of past ecosystems that are rooted in individual plant anatomy.
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45
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Domec JC, Smith DD, McCulloh KA. A synthesis of the effects of atmospheric carbon dioxide enrichment on plant hydraulics: implications for whole-plant water use efficiency and resistance to drought. PLANT, CELL & ENVIRONMENT 2017; 40:921-937. [PMID: 27739596 DOI: 10.1111/pce.12843] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 09/18/2016] [Accepted: 09/21/2016] [Indexed: 06/06/2023]
Abstract
Here, we summarize studies on the effects of elevated [CO2 ] (CO2e ) on the structure and function of plant hydraulic architecture and explore the implications of those changes using a model. Changes in conduit diameter and hydraulic conductance due to CO2e vary among species. Ring-porous species tend towards an increase in conduit size and consequently conductivity. The effect in diffuse-porous species is much more limited. In conifers, the results are mixed, some species show minor changes in xylem structure, while other studies found increases in tracheid density and diameter. Non-woody plants generally exhibited the reverse pattern with narrower conduits and lower hydraulic conductivity under CO2e . Further, changes in drought-resistance traits suggest that non-woody plants were the most affected by CO2e , which may permit them to better resist drought-induced embolism under future conditions. Due to their complexity, acclimation in hydraulic traits in response to CO2e is difficult to interpret when relying solely on measurements. When we examined how the observed tissues-specific trends might alter plant function, our modelling results suggest that these hydraulic changes would lead to reduced conductance and more frequent drought stress in trees that develop under CO2e with a more pronounced effect in isohydric than in anisohydric species.
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Affiliation(s)
- Jean-Christophe Domec
- Bordeaux Sciences Agro, UMR 1391 INRA-ISPA, 33175, Gradignan Cedex, France
- Nicholas School of the Environment, Duke University, Box 90328, Durham, NC, 27708, USA
| | - Duncan D Smith
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Kate A McCulloh
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
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46
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Venturas MD, Sperry JS, Hacke UG. Plant xylem hydraulics: What we understand, current research, and future challenges. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2017; 59:356-389. [PMID: 28296168 DOI: 10.1111/jipb.12534] [Citation(s) in RCA: 159] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 03/09/2017] [Indexed: 05/22/2023]
Abstract
Herein we review the current state-of-the-art of plant hydraulics in the context of plant physiology, ecology, and evolution, focusing on current and future research opportunities. We explain the physics of water transport in plants and the limits of this transport system, highlighting the relationships between xylem structure and function. We describe the great variety of techniques existing for evaluating xylem resistance to cavitation. We address several methodological issues and their connection with current debates on conduit refilling and exponentially shaped vulnerability curves. We analyze the trade-offs existing between water transport safety and efficiency. We also stress how little information is available on molecular biology of cavitation and the potential role of aquaporins in conduit refilling. Finally, we draw attention to how plant hydraulic traits can be used for modeling stomatal responses to environmental variables and climate change, including drought mortality.
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Affiliation(s)
- Martin D Venturas
- Department of Biology, University of Utah, 257 S 1400E, Salt Lake City, UT, 84112, USA
| | - John S Sperry
- Department of Biology, University of Utah, 257 S 1400E, Salt Lake City, UT, 84112, USA
| | - Uwe G Hacke
- Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G 2E3, Canada
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47
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Hacke UG, Spicer R, Schreiber SG, Plavcová L. An ecophysiological and developmental perspective on variation in vessel diameter. PLANT, CELL & ENVIRONMENT 2017; 40:831-845. [PMID: 27304704 DOI: 10.1111/pce.12777] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 05/27/2016] [Accepted: 05/31/2016] [Indexed: 05/05/2023]
Abstract
Variation in xylem vessel diameter is one of the most important parameters when evaluating plant water relations. This review provides a synthesis of the ecophysiological implications of variation in lumen diameter together with a summary of our current understanding of vessel development and its endogenous regulation. We analyzed inter-specific variation of the mean hydraulic vessel diameter (Dv ) across biomes, intra-specific variation of Dv under natural and controlled conditions, and intra-plant variation. We found that the Dv measured in young branches tends to stay below 30 µm in regions experiencing winter frost, whereas it is highly variable in the tropical rainforest. Within a plant, the widest vessels are often found in the trunk and in large roots; smaller diameters have been reported for leaves and small lateral roots. Dv varies in response to environmental factors and is not only a function of plant size. Despite the wealth of data on vessel diameter variation, the regulation of diameter is poorly understood. Polar auxin transport through the vascular cambium is a key regulator linking foliar and xylem development. Limited evidence suggests that auxin transport is also a determinant of vessel diameter. The role of auxin in cell expansion and in establishing longitudinal continuity during secondary growth deserve further study.
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Affiliation(s)
- Uwe G Hacke
- University of Alberta, Department of Renewable Resources, Edmonton, AB T6G 2E3, Canada
| | - Rachel Spicer
- Connecticut College, Department of Botany, New London, CT 06320, USA
| | - Stefan G Schreiber
- University of Alberta, Department of Renewable Resources, Edmonton, AB T6G 2E3, Canada
| | - Lenka Plavcová
- University of Hradec Králové, Department of Biology, Rokitanského 62, Hradec Králové, 500 03, Czech Republic
- Charles University, Department of Experimental Plant Biology, Viničná 5, Prague, 128 44, Czech Republic
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48
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Epila J, De Baerdemaeker NJF, Vergeynst LL, Maes WH, Beeckman H, Steppe K. Capacitive water release and internal leaf water relocation delay drought-induced cavitation in African Maesopsis eminii. TREE PHYSIOLOGY 2017; 37:481-490. [PMID: 28062725 DOI: 10.1093/treephys/tpw128] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 12/04/2016] [Indexed: 06/06/2023]
Abstract
The impact of drought on the hydraulic functioning of important African tree species, like Maesopsis eminii Engl., is poorly understood. To map the hydraulic response to drought-induced cavitation, sole reliance on the water potential at which 50% loss of xylem hydraulic conductivity (ψ50) occurs might be limiting and at times misleading as the value alone does not give a comprehensive overview of strategies evoked by M. eminii to cope with drought. This article therefore uses a methodological framework to study the different aspects of drought-induced cavitation and water relations in M. eminii. Hydraulic functioning of whole-branch segments was investigated during bench-top dehydration. Cumulative acoustic emissions and continuous weight measurements were used to quantify M. eminii's vulnerability to drought-induced cavitation and hydraulic capacitance. Wood structural traits, including wood density, vessel area, diameter and wall thickness, vessel grouping index, solitary vessel index and vessel wall reinforcement, were used to underpin observed physiological responses. On average, M. eminii's ψ50 (±SE) was -1.9 ± 0.1 MPa, portraying its xylem as drought vulnerable, just as one would expect for a common tropical pioneer. However, M. eminii additionally employed an interesting desiccation delay strategy, fuelled by internal relocation of leaf water, hydraulic capacitance and the presence of parenchyma around the xylem vessels. Our findings suggest that exclusive dependence on ψ50 would have misdirected our assessments of M. eminii's drought stress vulnerability. Hydraulic capacitance linked to anatomy and leaf-water relocation behaviour was equally important to better understand M. eminii's drought survival strategies. Because our study was conducted on branches of 3-year-old greenhouse-grown M. eminii seedlings, the findings cannot be simply extrapolated to adult M. eminii trees or their mature wood, because structural and physiological plant properties change with age. The techniques and methodological framework used in this study are, however, transferable to other species regardless of age.
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Affiliation(s)
- Jackie Epila
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium
- CAVElab Computational & Applied Vegetation Ecology, Department of Applied Ecology and Environmental Biology, Ghent University, Coupure links 653, B-9000 Ghent, Belgium
| | - Niels J F De Baerdemaeker
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000Ghent, Belgium
| | - Lidewei L Vergeynst
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000Ghent, Belgium
| | - Wouter H Maes
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 Ghent, Belgium
- Remote Sensing, University of Technology Sydney (UTS), 745 Harris Str., Broadway 2007, NSW, Australia
| | - Hans Beeckman
- Laboratory for Wood Biology and Xylarium (Royal Museum for Central Africa), Leuvensesteenweg 13, B-3080 Tervuren, Belgium
| | - Kathy Steppe
- Laboratory of Plant Ecology, Department of Applied Ecology and Environmental Biology, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000Ghent, Belgium
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49
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Ooeda H, Terashima I, Taneda H. Structures of Bordered Pits Potentially Contributing to Isolation of a Refilled Vessel from Negative Xylem Pressure in Stems of Morus australis Poir.: Testing of the Pit Membrane Osmosis and Pit Valve Hypotheses. PLANT & CELL PHYSIOLOGY 2017; 58:354-364. [PMID: 28013275 DOI: 10.1093/pcp/pcw196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Accepted: 11/08/2016] [Indexed: 06/06/2023]
Abstract
Two hypotheses have been proposed to explain the mechanism preventing the refilling vessel water from being drained to the neighboring functional vessels under negative pressure. The pit membrane osmosis hypothesis proposes that the xylem parenchyma cells release polysaccharides that are impermeable to the intervessel pit membranes into the refilling vessel; this osmotically counteracts the negative pressure, thereby allowing the vessel to refill. The pit valve hypothesis proposes that gas trapped within intervessel bordered pits isolates the refilling vessel water from the surrounding functional vessels. Here, using the single-vessel method, we assessed these hypotheses in shoots of mulberry (Morus australis Poir.). First, we confirmed the occurrence of xylem refilling under negative pressure in the potted mulberry saplings. To examine the pit membrane osmosis hypothesis, we estimated the semi-permeability of pit membranes for molecules of various sizes and found that the pit membranes were not semi-permeable to polyethylene glycol of molecular mass <20,000. For the pit valve hypothesis, we formed pit valves in the intervessel pits in the short stem segments and measured the maximum liquid pressure up to which gases in bordered pits were retained. The threshold pressure ranged from 0.025 to 0.10 MPa. These values matched the theoretical value calculated from the geometry of the pit chamber (0.0692-0.101 MPa). Our results suggest that gas in the pits is retained by surface tension, even under substantial positive pressure to resolve gases in the refilling vessel, whereas the molecule size required for the pit membrane osmosis mechanism in mulberry would be unrealistically large.
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Affiliation(s)
- Hiroki Ooeda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan
- Simplex Inc., Toranomon, Minato-ku, Tokyo, Japan
| | - Ichiro Terashima
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan
| | - Haruhiko Taneda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan
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50
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Scoffoni C, Albuquerque C, Brodersen CR, Townes SV, John GP, Cochard H, Buckley TN, McElrone AJ, Sack L. Leaf vein xylem conduit diameter influences susceptibility to embolism and hydraulic decline. THE NEW PHYTOLOGIST 2017; 213:1076-1092. [PMID: 27861926 DOI: 10.1111/nph.14256] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 09/10/2016] [Indexed: 05/24/2023]
Abstract
Ecosystems worldwide are facing increasingly severe and prolonged droughts during which hydraulic failure from drought-induced embolism can lead to organ or whole plant death. Understanding the determinants of xylem failure across species is especially critical in leaves, the engines of plant growth. If the vulnerability segmentation hypothesis holds within leaves, higher order veins that are most terminal in the plant hydraulic system should be more susceptible to embolism to protect the rest of the water transport system. Increased vulnerability in the higher order veins would also be consistent with these experiencing the greatest tensions in the plant xylem network. To test this hypothesis, we combined X-ray micro-computed tomography imaging, hydraulic experiments, cross-sectional anatomy and 3D physiological modelling to investigate how embolisms spread throughout petioles and vein orders during leaf dehydration in relation to conduit dimensions. Decline of leaf xylem hydraulic conductance (Kx ) during dehydration was driven by embolism initiating in petioles and midribs across all species, and Kx vulnerability was strongly correlated with petiole and midrib conduit dimensions. Our simulations showed no significant impact of conduit collapse on Kx decline. We found xylem conduit dimensions play a major role in determining the susceptibility of the leaf water transport system during strong leaf dehydration.
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Affiliation(s)
- Christine Scoffoni
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
- Department of Biology, Utah State University, Logan, UT, 84322, USA
| | - Caetano Albuquerque
- Department of Viticulture and Enology, University of California, Davis, CA, 95616, USA
| | - Craig R Brodersen
- School of Forestry & Environmental Studies, Yale University, 195 Prospect Street, New Haven, CT, 06511, USA
| | - Shatara V Townes
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
| | - Grace P John
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
| | - Hervé Cochard
- PIAF, INRA, Univ. Clermont-Auvergne, Clermont-Ferrand, 63100, France
| | - Thomas N Buckley
- Plant Breeding Institute, Faculty of Agriculture and Environment, The University of Sydney, 12656 Newell Hwy, Narrabri, NSW, 2390, Australia
| | - Andrew J McElrone
- Department of Viticulture and Enology, University of California, Davis, CA, 95616, USA
- USDA-Agricultural Research Service, Davis, CA, 95616, USA
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA, 90095, USA
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