1
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Jacobsen AL, Venturas MD, Hacke UG, Pratt RB. Sap flow through partially embolized xylem vessel networks. PLANT, CELL & ENVIRONMENT 2024; 47:3375-3392. [PMID: 38826042 DOI: 10.1111/pce.14990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2023] [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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Pereira L, Kaack L, Guan X, Silva LDM, Miranda MT, Pires GS, Ribeiro RV, Schenk HJ, Jansen S. Angiosperms follow a convex trade-off to optimize hydraulic safety and efficiency. THE NEW PHYTOLOGIST 2023; 240:1788-1801. [PMID: 37691289 DOI: 10.1111/nph.19253] [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: 06/19/2023] [Accepted: 08/11/2023] [Indexed: 09/12/2023]
Abstract
Intervessel pits are considered to function as valves that avoid embolism spreading and optimize efficient transport of xylem sap across neighbouring vessels. Hydraulic transport between vessels would therefore follow a safety-efficiency trade-off, which is directly related to the total intervessel pit area (Ap ), inversely related to the pit membrane thickness (TPM ) and driven by a pressure difference. To test this hypothesis, we modelled the relative transport rate of gas (ka ) and water (Q) at the intervessel pit level for 23 angiosperm species and correlated these parameters with the water potential at which 50% of embolism occurs (Ψ50 ). We also measured ka for 10 species using pneumatic measurements. The pressure difference across adjacent vessels and estimated values of ka and Q were related to Ψ50 , following a convex safety-efficiency trade-off based on modelled and experimental data. Minor changes in TPM and Ap exponentially affected the pressure difference and flow, respectively. Our results provide clear evidence that a xylem safety-efficiency trade-off is not linear, but convex due to flow across intervessel pit membranes, which represent mesoporous media within microporous conduits. Moreover, the convex nature of long-distance xylem transport may contribute to an adjustable fluid balance of plants, depending on environmental conditions.
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Affiliation(s)
- Luciano Pereira
- Institute of Botany, Ulm University, 89081, Ulm, Albert-Einstein-Allee 11, Germany
| | - Lucian Kaack
- Institute of Botany, Ulm University, 89081, Ulm, Albert-Einstein-Allee 11, Germany
- Botanical Garden of Ulm University, 89081, Ulm, Hans-Krebs-Weg, Germany
| | - Xinyi Guan
- Institute of Botany, Ulm University, 89081, Ulm, Albert-Einstein-Allee 11, Germany
- Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, 530004, Guangxi, Nanning, China
| | | | - Marcela T Miranda
- Laboratory of Plant Physiology 'Coaracy M. Franco', Center R&D in Ecophysiology and Biophysics, Agronomic Institute (IAC), PO Box 28, Campinas, 13012-970, SP, Brazil
| | - Gabriel S Pires
- Department of Plant Biology, Laboratory of Crop Physiology, Institute of Biology, University of Campinas (UNICAMP), 13083-970, SP, Campinas, PO Box 6109, Brazil
| | - Rafael V Ribeiro
- Department of Plant Biology, Laboratory of Crop Physiology, Institute of Biology, University of Campinas (UNICAMP), 13083-970, SP, Campinas, PO Box 6109, Brazil
| | - H Jochen Schenk
- Department of Biological Science, California State University Fullerton, 800 N. State College Blvd, Fullerton, 92831-3599, CA, USA
| | - Steven Jansen
- Institute of Botany, Ulm University, 89081, Ulm, Albert-Einstein-Allee 11, Germany
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4
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Miranda A, Syphard AD, Berdugo M, Carrasco J, Gómez-González S, Ovalle JF, Delpiano CA, Vargas S, Squeo FA, Miranda MD, Dobbs C, Mentler R, Lara A, Garreaud R. Widespread synchronous decline of Mediterranean-type forest driven by accelerated aridity. NATURE PLANTS 2023; 9:1810-1817. [PMID: 37845335 DOI: 10.1038/s41477-023-01541-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 09/12/2023] [Indexed: 10/18/2023]
Abstract
Large-scale, abrupt ecosystem change in direct response to climate extremes is a critical but poorly documented phenomenon1. Yet, recent increases in climate-induced tree mortality raise concern that some forest ecosystems are on the brink of collapse across wide environmental gradients2,3. Here we assessed climatic and productivity trends across the world's five Mediterranean forest ecosystems from 2000 to 2021 and detected a large-scale, abrupt forest browning and productivity decline in Chile (>90% of the forest in <100 days), responding to a sustained, acute drought. The extreme dry and warm conditions in Chile, unprecedented in the recent history of all Mediterranean-type ecosystems, are akin to those projected to arise in the second half of the century4. Long-term recovery of this forest is uncertain given an ongoing decline in regional water balance. This dramatic plummet of forest productivity may be a spyglass to the future for other Mediterranean ecosystems.
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Affiliation(s)
- Alejandro Miranda
- Laboratorio de Ecología del Paisaje y Conservación, Departamento de Ciencias Forestales, Universidad de La Frontera, Temuco, Chile.
- Center for Climate and Resilience Research (CR2), Santiago, Chile.
| | - Alexandra D Syphard
- Department of Geography, San Diego State University, San Diego, CA, USA
- Conservation Biology Institute, Corvallis, OR, USA
| | - Miguel Berdugo
- Institute of Integrative Biology, Department of Environment Systems Science, ETH Zurich, Zürich, Switzerland
| | - Jaime Carrasco
- Departamento de Industria, Facultad de Ingeniería, Universidad Tecnológica Metropolitana, Santiago, Chile
| | - Susana Gómez-González
- Center for Climate and Resilience Research (CR2), Santiago, Chile
- Departamento de Biología-IVAGRO, Universidad de Cádiz, Puerto Real, Spain
- Center for Fire and Socioecological Systems (FireSES), Universidad Austral de Chile, Valdivia, Chile
| | - Juan F Ovalle
- Facultad de Ciencias Forestales y de La Conservación de la Naturaleza, Universidad de Chile, Santiago, Chile
- Center of Applied Ecology and Sustainability (CAPES), Santiago, Chile
| | - Cristian A Delpiano
- Departamento de Biología, Facultad de Ciencias, Universidad de La Serena, La Serena, Chile
- Instituto de Ecología y Biodiversidad (IEB), Santiago, Chile
| | - Solange Vargas
- Departamento de Química y Biología, Facultad de Ciencias Naturales, Universidad de Atacama, Copiapó, Chile
| | - Francisco A Squeo
- Departamento de Biología, Facultad de Ciencias, Universidad de La Serena, La Serena, Chile
- Instituto de Ecología y Biodiversidad (IEB), Santiago, Chile
| | - Marcelo D Miranda
- Center of Applied Ecology and Sustainability (CAPES), Santiago, Chile
- Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Cynnamon Dobbs
- Department of Natural Resources and the Environment, University of Connecticut, Mansfield, CT, USA
| | - Rayen Mentler
- Center for Climate and Resilience Research (CR2), Santiago, Chile
| | - Antonio Lara
- Center for Climate and Resilience Research (CR2), Santiago, Chile
- Instituto de Conservación, Biodiversidad y Territorio, Universidad Austral de Chile, Valdivia, Chile
- Fundación Centro de los Bosques Nativos FORECOS, Valdivia, Chile
| | - René Garreaud
- Center for Climate and Resilience Research (CR2), Santiago, Chile
- Departamento de Geofísica, Universidad de Chile, Santiago, Chile
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5
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Yang D, Wang YSD, Wang Q, Ke Y, Zhang YB, Zhang SB, Zhang YJ, McDowell NG, Zhang JL. Physiological response and photosynthetic recovery to an extreme drought: Evidence from plants in a dry-hot valley savanna of Southwest China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 868:161711. [PMID: 36682563 DOI: 10.1016/j.scitotenv.2023.161711] [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: 10/21/2022] [Revised: 01/15/2023] [Accepted: 01/15/2023] [Indexed: 06/17/2023]
Abstract
The frequency of extreme drought events has been rising worldwide, but due to its unpredictability, how plants will respond remains poorly understood. Here, we aimed to characterize how the hydraulics and photosynthesis of savanna plants respond to extreme drought, and tested whether they can subsequently recover photosynthesis after drought. There was an extreme drought in 2019 in Southwest (SW) China. We investigated photosynthetic gas exchange, leaf-, stem-, and whole-shoot hydraulic conductance of 18 plant species with diverse leaf habits (deciduous, semi-deciduous and evergreen) and growth forms (tree and shrub) from a dry-hot valley savanna in SW China for three rainy seasons from 2019 to 2021. We also compared photosynthetic gas exchange to those of a regular year (2014). We found that leaf stomatal and hydraulic conductance and maximum photosynthetic rate were significantly lower during the drought in 2019 than in the wetter years. In 2019, all studied plants maintained stomatal conductance at their minimum level observed, which could be related to high vapor pressure deficits (VPD, >2 kPa). However, no significant difference in stem and shoot hydraulic conductance was detected across years. The reductions in leaf hydraulic conductance and stomatal regulation under extreme drought might help keep the stem hydraulic function. Stomatal conductance and photosynthesis after drought (2020 and 2021) showed comparable or even higher values compared to that of 2014, suggesting high recovery of photosynthetic gas exchange. In addition, the response of hydraulic and photosynthetic traits to extreme drought was convergent across leaf habits and growth forms. Our results will help better understand the physiological mechanism underlying the response of savanna ecosystems to climate change.
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Affiliation(s)
- Da Yang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
| | - Yang-Si-Ding Wang
- 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
| | - Qin Wang
- 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
| | - Yan Ke
- 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
| | - Yun-Bing Zhang
- 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
| | - Shi-Bao Zhang
- Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China
| | - Yong-Jiang Zhang
- School of Biology and Ecology, University of Maine, Orono, ME 04469, USA.
| | - Nate G McDowell
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, USA; School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164-4236, USA
| | - Jiao-Lin Zhang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China.
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6
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Melián E, Gatica G, Pucheta E. Wood trait trade‐offs in desert plants: A triangular model to understand intra‐ and interspecific variations along an aridity gradient. AUSTRAL ECOL 2023. [DOI: 10.1111/aec.13300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2023]
Affiliation(s)
- Edgardo Melián
- Departamento de Biología, Facultad de Ciencias Exactas, Físicas y Naturales Universidad Nacional de San Juan San Juan Argentina
| | - Gabriel Gatica
- Instituto de Innovación para la Producción Agropecuaria y Desarrollo Sostenible UEDD INTA CONICET Tandil Argentina
| | - Eduardo Pucheta
- Departamento de Biología, Facultad de Ciencias Exactas, Físicas y Naturales Universidad Nacional de San Juan San Juan Argentina
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7
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Martinez P, Serpe M, Barron R, Buerki S. Acclimation and hardening of a slow-growing woody species emblematic to western North America from in vitro plantlets. APPLICATIONS IN PLANT SCIENCES 2023; 11:e11515. [PMID: 37051580 PMCID: PMC10083460 DOI: 10.1002/aps3.11515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 12/09/2022] [Accepted: 12/15/2022] [Indexed: 06/19/2023]
Abstract
PREMISE Determining the tolerance of plant populations to climate change requires the development of biotechnological protocols producing genetically identical individuals used for genotype-by-environment experiments. Such protocols are missing for slow-growth, woody plants; to address this gap, this study uses Artemisia tridentata, a western North American keystone shrub, as model. METHODS AND RESULTS The production of individual lines is a two-step process: in vitro propagation under aseptic conditions followed by ex vitro acclimation and hardening. Due to aseptic growth conditions, in vitro plantlets exhibit maladapted phenotypes, and this protocol focuses on presenting an approach promoting morphogenesis for slow-growth, woody species. Survival was used as the main criterion determining successful acclimation and hardening. Phenotypic changes were confirmed by inspecting leaf anatomy, and shoot water potential was used to ensure that plantlets were not water stressed. CONCLUSIONS Although our protocol has lower survival rates (11-41%) compared to protocols developed for herbaceous, fast-growing species, it provides a benchmark for slow-growth, woody species occurring in dry ecosystems.
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Affiliation(s)
- Peggy Martinez
- Department of Biological SciencesBoise State UniversityBoiseIdahoUSA
| | - Marcelo Serpe
- Department of Biological SciencesBoise State UniversityBoiseIdahoUSA
| | | | - Sven Buerki
- Department of Biological SciencesBoise State UniversityBoiseIdahoUSA
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8
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Soheili F, Abdul-Hamid H, Almasi I, Heydari M, Tongo A, Woodward S, Naji HR. How Tree Decline Varies the Anatomical Features in Quercus brantii. PLANTS (BASEL, SWITZERLAND) 2023; 12:377. [PMID: 36679089 PMCID: PMC9866467 DOI: 10.3390/plants12020377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/23/2022] [Accepted: 12/29/2022] [Indexed: 06/17/2023]
Abstract
Drought has serious effects on forests, especially semi-arid and arid forests, around the world. Zagros Forest in Iran has been severely affected by drought, which has led to the decline of the most common tree species, Persian oak (Quercus brantii). The objective of this study was to determine the effects of drought on the anatomical structure of Persian oak. Three healthy and three declined trees were sampled from each of two forest sites in Ilam Forest. Discs were cut at breast height, and three sapwood blocks were taken near the bark of each tree for sectioning. The anatomical characteristics measured included fiber length (FL), fiber wall thickness (FWT), number of axial parenchymal cells (NPC), ray number (RN), ray width (RW), and number of calcium oxalate crystals. Differences between healthy and declined trees were observed in the abundance of NPC and in RN, FL, and FWT, while no differences occurred in the number of oxalate crystals. The decline had uncertain effects on the FL of trees from sites A and B, which showed values of 700.5 and 837.3 μm compared with 592.7 and 919.6 μm in healthy trees. However, the decline resulted in an increase in the FWT of trees from sites A and B (9.33 and 11.53 μm) compared with healthy trees (5.23 and 9.56 μm). NPC, RN, and RW also increased in declined individuals from sites A and B (28.40 and 28.40 mm−1; 41.06 and 48.60 mm−1; 18.60 and 23.20 μm, respectively) compared with healthy trees (20.50 and 19.63 mm−2; 31.60 and 28.30 mm−2; 17.93 and 15.30 μm, respectively). Thus, drought caused measurable changes in the anatomical characteristics of declined trees compared with healthy trees.
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Affiliation(s)
- Forough Soheili
- Department of Forest Sciences, Ilam University, Ilam 67187-73654, Iran
| | - Hazandy Abdul-Hamid
- Faculty of Forestry and Environment, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
| | - Isaac Almasi
- Faculty of Science, Department of Statistics, Razi University, Kermanshah 67144-14971, Iran
| | - Mehdi Heydari
- Department of Forest Sciences, Ilam University, Ilam 67187-73654, Iran
| | - Afsaneh Tongo
- Department of Forest Science and Engineering, Sari University of Agricultural Sciences and Natural Resources, Sari 48181-68984, Iran
| | - Stephen Woodward
- School of Biological Sciences, University of Aberdeen, Aberdeen AB24 3UU, UK
| | - Hamid Reza Naji
- Department of Forest Sciences, Ilam University, Ilam 67187-73654, Iran
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9
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Verslues PE, Bailey-Serres J, Brodersen C, Buckley TN, Conti L, Christmann A, Dinneny JR, Grill E, Hayes S, Heckman RW, Hsu PK, Juenger TE, Mas P, Munnik T, Nelissen H, Sack L, Schroeder JI, Testerink C, Tyerman SD, Umezawa T, Wigge PA. Burning questions for a warming and changing world: 15 unknowns in plant abiotic stress. THE PLANT CELL 2023; 35:67-108. [PMID: 36018271 PMCID: PMC9806664 DOI: 10.1093/plcell/koac263] [Citation(s) in RCA: 43] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 08/21/2022] [Indexed: 05/08/2023]
Abstract
We present unresolved questions in plant abiotic stress biology as posed by 15 research groups with expertise spanning eco-physiology to cell and molecular biology. Common themes of these questions include the need to better understand how plants detect water availability, temperature, salinity, and rising carbon dioxide (CO2) levels; how environmental signals interface with endogenous signaling and development (e.g. circadian clock and flowering time); and how this integrated signaling controls downstream responses (e.g. stomatal regulation, proline metabolism, and growth versus defense balance). The plasma membrane comes up frequently as a site of key signaling and transport events (e.g. mechanosensing and lipid-derived signaling, aquaporins). Adaptation to water extremes and rising CO2 affects hydraulic architecture and transpiration, as well as root and shoot growth and morphology, in ways not fully understood. Environmental adaptation involves tradeoffs that limit ecological distribution and crop resilience in the face of changing and increasingly unpredictable environments. Exploration of plant diversity within and among species can help us know which of these tradeoffs represent fundamental limits and which ones can be circumvented by bringing new trait combinations together. Better defining what constitutes beneficial stress resistance in different contexts and making connections between genes and phenotypes, and between laboratory and field observations, are overarching challenges.
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Affiliation(s)
| | - Julia Bailey-Serres
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, California 92521, USA
| | - Craig Brodersen
- School of the Environment, Yale University, New Haven, Connecticut 06511, USA
| | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, California 95616, USA
| | - Lucio Conti
- Department of Biosciences, University of Milan, Milan 20133, Italy
| | - Alexander Christmann
- School of Life Sciences, Technical University Munich, Freising-Weihenstephan 85354, Germany
| | - José R Dinneny
- Department of Biology, Stanford University, Stanford, California 94305, USA
| | - Erwin Grill
- School of Life Sciences, Technical University Munich, Freising-Weihenstephan 85354, Germany
| | - Scott Hayes
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University and Research, Wageningen 6708 PB, The Netherlands
| | - Robert W Heckman
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712, USA
| | - Po-Kai Hsu
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, La Jolla, California 92093, USA
| | - Thomas E Juenger
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712, USA
| | - Paloma Mas
- Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Barcelona 08193, Spain
- Consejo Superior de Investigaciones Científicas (CSIC), Barcelona 08028, Spain
| | - Teun Munnik
- Department of Plant Cell Biology, Green Life Sciences Cluster, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam NL-1098XH, The Netherlands
| | - Hilde Nelissen
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent 9052, Belgium
- VIB Center for Plant Systems Biology, Ghent 9052, Belgium
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, Institute of the Environment and Sustainability, University of California, Los Angeles, California 90095, USA
| | - Julian I Schroeder
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California San Diego, La Jolla, California 92093, USA
| | - Christa Testerink
- Laboratory of Plant Physiology, Plant Sciences Group, Wageningen University and Research, Wageningen 6708 PB, The Netherlands
| | - Stephen D Tyerman
- ARC Center Excellence, Plant Energy Biology, School of Agriculture Food and Wine, University of Adelaide, Adelaide, South Australia 5064, Australia
| | - Taishi Umezawa
- Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 6708 PB, Japan
| | - Philip A Wigge
- Leibniz-Institut für Gemüse- und Zierpflanzenbau, Großbeeren 14979, Germany
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam 14476, Germany
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10
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dos Santos P, Brilhante MÂ, Messerschmid TFE, Serrano HC, Kadereit G, Branquinho C, de Vos JM. Plant growth forms dictate adaptations to the local climate. FRONTIERS IN PLANT SCIENCE 2022; 13:1023595. [PMID: 36479511 PMCID: PMC9720395 DOI: 10.3389/fpls.2022.1023595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 10/31/2022] [Indexed: 06/17/2023]
Abstract
Adaptive radiation is a significant driver of biodiversity. Primarily studied in animal systems, mechanisms that trigger adaptive radiations remain poorly understood in plants. A frequently claimed indicator of adaptive radiation in plants is growth form diversity when tied to the occupation of different habitats. However, it remains obscure whether morphological adaptations manifest as growth form diversity per se or as its constituent traits. We use the classic Aeonium radiation from the Canary Islands to ask whether adaptation across climatic space is structured by growth form evolution. Using morphological sampling with site-associated climate in a phylogenetic context, we find that growth forms dictate adaptations to the local environment. Furthermore, we demonstrate that the response of specific traits to analogous environments is antagonistic when growth forms are different. This finding suggests for the first time that growth forms represent particular ecological functions, allowing the co-occurrence of closely related species, being a product of divergent selection during evolution in sympatry.
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Affiliation(s)
- Patrícia dos Santos
- Centre for Ecology, Evolution and Environmental Changes (cE3c) & Global Change and Sustainability Institute (CHANGE), Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
- Department of Environmental Sciences – Botany, University of Basel, Basel, Switzerland
| | - Miguel Ângelo Brilhante
- Linking Landscape, Environment, Agriculture and Food (LEAF), Instituto Superior de Agronomia (ISA), Universidade de Lisboa, Lisbon, Portugal
| | - Thibaud F. E. Messerschmid
- Botanischer Garten München-Nymphenburg und Botanischen Staatssammlung, Staatliche Naturwissenschaftliche Sammlungen Bayerns, Munich, Germany
- Prinzessin Therese von Bayern Lehrstuhl für Systematik, Biodiversität & Evolution der Pflanzen, Ludwig-Maximilans-Universität München, Munich, Germany
| | - Helena Cristina Serrano
- Centre for Ecology, Evolution and Environmental Changes (cE3c) & Global Change and Sustainability Institute (CHANGE), Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Gudrun Kadereit
- Botanischer Garten München-Nymphenburg und Botanischen Staatssammlung, Staatliche Naturwissenschaftliche Sammlungen Bayerns, Munich, Germany
- Prinzessin Therese von Bayern Lehrstuhl für Systematik, Biodiversität & Evolution der Pflanzen, Ludwig-Maximilans-Universität München, Munich, Germany
| | - Cristina Branquinho
- Centre for Ecology, Evolution and Environmental Changes (cE3c) & Global Change and Sustainability Institute (CHANGE), Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Jurriaan M. de Vos
- Department of Environmental Sciences – Botany, University of Basel, Basel, Switzerland
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11
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Bouda M, Huggett BA, Prats KA, Wason JW, Wilson JP, Brodersen CR. Hydraulic failure as a primary driver of xylem network evolution in early vascular plants. Science 2022; 378:642-646. [DOI: 10.1126/science.add2910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The earliest vascular plants had stems with a central cylindrical strand of water-conducting xylem, which rapidly diversified into more complex shapes. This diversification is understood to coincide with increases in plant body size and branching; however, no selection pressure favoring xylem strand-shape complexity is known. We show that incremental changes in xylem network organization that diverge from the cylindrical ancestral form lead to progressively greater drought resistance by reducing the risk of hydraulic failure. As xylem strand complexity increases, independent pathways for embolism spread become fewer and increasingly concentrated in more centrally located conduits, thus limiting the systemic spread of embolism during drought. Selection by drought may thus explain observed trajectories of xylem strand evolution in the fossil record and the diversity of extant forms.
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Affiliation(s)
- Martin Bouda
- Institute of Botany, Czech Academy of Sciences, Průhonice, Czechia
| | | | - Kyra A. Prats
- Yale School of the Environment, New Haven, CT, USA
- New York Botanical Garden, Bronx, NY, USA
| | - Jay W. Wason
- School of Forest Resources, University of Maine, Orono, ME, USA
| | - Jonathan P. Wilson
- Department of Environmental Studies, Haverford College, Haverford, PA, USA
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12
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Jalil AM, Abdul-Hamid H, Sahrim-Lias, Anwar-Uyup MK, Md-Tahir P, Mohd-Razali S, Mohd-Noor AA, Syazwan SA, Shamsul-Anuar AS, Mohamad Kasim MR, Mohamed J, Abiri R. Assessment of the Effects of Artificial Fungi Inoculations on Agarwood Formation and Sap Flow Rate of Aquilaria malaccensis Lam. Using Sonic Tomography (SoT) and Sap Flow Meter (SFM). FORESTS 2022; 13:1731. [DOI: 10.3390/f13101731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
Agarwood is a valuable aromatic resinous wood that is biosynthesised when a fungal attack injures the healthy wood tissue of the Aquilaria tree. The magnitude of infection related to sap flow (SF) is one of the most critical functional traits to evaluate the tree’s response to various adverse conditions. Therefore, the objective of this study was to investigate the reliability of sonic tomography (SoT) and sap flow meter (SFM) in studying the influence of inoculation fungi Pichia kudriavzevii Boidin, Pignal and Besson, and Paecilomyces niveus Stolk and Samson, on deteriorated wood (Dt) and SF rate in Aquilaria malaccensis Lam. A. malaccensis trees with small, medium, and large diameters were inoculated with each fungus separately at the bottom, middle, and top positions of the tree and the area of sapwood was measured after 6, 12, and 24 months to stimulate the agarwood formation. Furthermore, the SF rate was assessed using SFM in the position of the selected trees. There was a significant difference (p ≤ 0.05) in Dt% and SF rate between inoculated and uninoculated trees. The Dt percentage in trees inoculated with P. kudriavzevii, P. niveus, and control trees was 25.6%, 25.7%, and 15.0%, respectively. The SF rate was lower in P. kudriavzevii, with 207.7 cm3/h, than in the control trees, with 312.9 cm3/h in the small-diameter class. In summary, the results of this study emphasise the importance of inoculation duration (24 months) and the effects of water conductivity, especially tree diameter class (small), on the biosynthetic response of resinous substance.
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13
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Keeley JE, Brennan TJ, Syphard AD. The effects of prolonged drought on vegetation dieback and megafires in southern California chaparral. Ecosphere 2022. [DOI: 10.1002/ecs2.4203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Jon E. Keeley
- U.S. Geological Survey, Western Ecological Research Center, Sequoia‐Kings Canyon Field Station Three Rivers California USA
- Department of Ecology and Evolutionary Biology University of California Los Angeles California USA
| | - Teresa J. Brennan
- U.S. Geological Survey, Western Ecological Research Center, Sequoia‐Kings Canyon Field Station Three Rivers California USA
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14
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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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15
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Jiang (蒋国凤) GF, Li (李溯源) SY, Li (李艺蝉) YC, Roddy AB. Coordination of hydraulic thresholds across roots, stems, and leaves of two co-occurring mangrove species. PLANT PHYSIOLOGY 2022; 189:2159-2174. [PMID: 35640109 PMCID: PMC9342987 DOI: 10.1093/plphys/kiac240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 05/09/2022] [Indexed: 05/30/2023]
Abstract
Mangroves are frequently inundated with saline water and have evolved different anatomical and physiological mechanisms to filter and, in some species, excrete excess salt from the water they take up. Because salts impose osmotic stress, interspecific differences in salt tolerance and salt management strategy may influence physiological responses to drought throughout the entire plant hydraulic pathway, from roots to leaves. Here, we characterized embolism vulnerability simultaneously in leaves, stems, and roots of seedlings of two mangrove species (Avicennia marina and Bruguiera gymnorrhiza) along with turgor-loss points in roots and leaves and xylem anatomical traits. In both species, the water potentials causing 50% of total embolism were less negative in roots and leaves than they were in stems, but the water potentials causing incipient embolism (5%) were similar in roots, stems, and leaves. Stomatal closure in leaves and turgor loss in both leaves and roots occurred at water potentials only slightly less negative than the water potentials causing 5% of total embolism. Xylem anatomical traits were unrelated to vulnerability to embolism. Vulnerability segmentation may be important in limiting embolism spread into stems from more vulnerable roots and leaves. Interspecific differences in salt tolerance affected hydraulic traits from roots to leaves: the salt-secretor A. marina lost turgor at more negative water potentials and had more embolism-resistant xylem than the salt-excluder B. gymnorrhiza. Characterizing physiological thresholds of roots may help to explain recent mangrove mortality after drought and extended saltwater inundation.
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Affiliation(s)
| | - Su-Yuan Li (李溯源)
- Guangxi Key Laboratory of Forest Ecology and Conservation, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Nanning 530004, China
| | - Yi-Chan Li (李艺蝉)
- Guangxi Key Laboratory of Forest Ecology and Conservation, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Nanning 530004, China
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16
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Suissa JS, Friedman WE. Rapid diversification of vascular architecture underlies the Carboniferous fern radiation. Proc Biol Sci 2022; 289:20212209. [PMID: 35473384 PMCID: PMC9043699 DOI: 10.1098/rspb.2021.2209] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Vascular plants account for 93% of Earth's terrestrial flora. Xylem and phloem, vital for transporting water and nutrients through the plant, unite this diverse clade. Three-dimensional arrangements of these tissues (vascular architecture) are manifold across living and extinct species. However, the evolutionary processes underlying this variation remain elusive. Using ferns, a diverse clade with multiple radiations over their ca 400-million-year history, we synthesized data across 3339 species to explore the tempo and mode of vascular evolution and to contextualize dynamics of phenotypic innovation during major fern diversification events. Our results reveal three paradigm shifts in our understanding of fern vascular evolution. (i) The canonical theory on the stepwise and unidirectional evolution of vascular architecture does not capture the complexities of character evolution among ferns. Rather, a new model permitting additional transitions, rate heterogeneity and multiple reversions is more likely. (ii) Major shifts in vascular architecture correspond to developmental changes in body size, not regional water availability. (iii) The early Carboniferous radiation of crown-group ferns was characterized by an explosion of phenotypic innovation. By contrast, during the Cretaceous and Cenozoic rise of eupolypods, rates of vascular evolution were dramatically low and seemingly decoupled from lineage diversification.
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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, 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, Boston, MA 02131, USA
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17
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Shen JX, Zhang YJ, Maenpuen P, Zhang SB, Zhang L, Yang L, Tao LB, Yan PY, Zhang ZM, Li SQ, Yuan X, Kongjarat W, Kaewkamol S, Tinprabat P, Chen YJ. Response of four evergreen savanna shrubs to an incidence of extreme drought: high embolism resistance, branch shedding and maintenance of nonstructural carbohydrates. TREE PHYSIOLOGY 2022; 42:740-753. [PMID: 35020937 DOI: 10.1093/treephys/tpab150] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 10/20/2021] [Indexed: 06/14/2023]
Abstract
Extreme drought events are becoming frequent globally, resulting in widespread plant mortality and forest dieback. Although savanna vegetation cover ~20% of the earth's land area, their responses to extreme drought have been less studied than that of forests. Herein, we quantified branch dieback, individual mortality and the associated physiological responses of four evergreen shrubs (Tarenna depauperate Hutch., Maytenus esquirolii (H. Lév.) C.Y. Cheng, Murraya exotica L., Jasminum nudiflorum Lindl.) in a savanna ecosystem in Southwest China to an incidence of extreme drought during 2019 and 2020. We found that 80-100% of the individuals of these species exhibited branch dieback, whereas individual mortality was only found in T. depauperate (4.5%). All species showed high resistance to stem embolism (P50, water potential at 50% loss of hydraulic conductivity ranged from -5.62 to -8.6 MPa), whereas the stem minimum water potentials reached -7.6 to ca -10.0 MPa during the drought. The low water potential caused high native embolism levels (percentage loss of hydraulic conductivity (PLC) 23-65%) in terminal branches, and the remaining stems maintained 15-35% PLC at the end of the drought. Large within-individual variations in stem vulnerability to embolism were detected, and shedding of vulnerable branches could be a mechanism for shrubs to reduce water and carbon consumption. Overall, the content of total nonstructural carbohydrates (NSC) and their components in the stem were generally comparable to or higher than those in the rainy season in three of the four species. Because the leaves were turgor-less for most time during the drought, high NSC levels during the drought could be due to recycling of NSC from dead branches or translocation from roots. Our results suggest high tolerance of savanna shrub species to extreme drought, which could be facilitated by high embolism resistance in some stems and shedding of vulnerable branches to maintain individual water and carbon balance.
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Affiliation(s)
- Jing-Xian Shen
- Institute of Ecology and Geobotany, School of Ecology and Environmental Sciences, Yunnan University, Kunming, Yunnan 650091, China
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- Yuanjiang Savanna Ecosystem Research Station, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yuanjiang, Yunnan 6663300, China
| | - Yong-Jiang Zhang
- School of Biology and Ecology, University of Maine, Orono, ME 04469, USA
| | - Phisamai Maenpuen
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Shu-Bin Zhang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Beijing 100093, China
| | - Lan Zhang
- School of Geography and Ecotoursim, Southwest Forestry University, Panlong District, Kunming, Yunnan 650224, China
| | - Lin Yang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
| | - Lian-Bin Tao
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
| | - Peng-Yun Yan
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
| | - Zhi-Ming Zhang
- Institute of Ecology and Geobotany, School of Ecology and Environmental Sciences, Yunnan University, Kunming, Yunnan 650091, China
| | - Shu-Qiong Li
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Xia Yuan
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Wanwalee Kongjarat
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Sasiwimol Kaewkamol
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Pimnara Tinprabat
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Ya-Jun Chen
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
- Yuanjiang Savanna Ecosystem Research Station, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yuanjiang, Yunnan 6663300, China
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Beijing 100093, China
- Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Yunnan 666303, China
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18
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Avila RT, Guan X, Kane CN, Cardoso AA, Batz TA, DaMatta FM, Jansen S, McAdam SAM. Xylem embolism spread is largely prevented by interconduit pit membranes until the majority of conduits are gas-filled. PLANT, CELL & ENVIRONMENT 2022; 45:1204-1215. [PMID: 34984700 DOI: 10.1111/pce.14253] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 11/29/2021] [Accepted: 12/11/2021] [Indexed: 06/14/2023]
Abstract
Xylem embolism resistance varies across species influencing drought tolerance, yet little is known about the determinants of the embolism resistance of an individual conduit. Here we conducted an experiment using the optical vulnerability method to test whether individual conduits have a specific water potential threshold for embolism formation and whether pre-existing embolism in neighbouring conduits alters this threshold. Observations were made on a diverse sample of angiosperm and conifer species through a cycle of dehydration, rehydration and subsequent dehydration to death. Upon rehydration after the formation of embolism, no refilling was observed. When little pre-existing embolism was present, xylem conduits had a conserved, individual embolism-resistance threshold that varied across the population of conduits. The consequence of a variable conduit-specific embolism threshold is that a small degree of pre-existing embolism in the xylem results in apparently more resistant xylem in subsequent dehydrations, particularly in angiosperms with vessels. While our results suggest that pit membranes separating xylem conduits are critical for maintaining a conserved individual conduit threshold for embolism when little pre-existing embolism is present, as the percentage of embolized conduits increases, gas movement, local pressure differences and connectivity between conduits increasingly contribute to embolism spread.
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Affiliation(s)
- Rodrigo T Avila
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, Indiana, USA
| | - Xinyi Guan
- Institute of Systematic Botany and Ecology, Faculty of Natural Sciences, Ulm University, Ulm, Baden-Württemberg, Germany
| | - Cade N Kane
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, Indiana, USA
| | - Amanda A Cardoso
- Instituto de Ciências da Natureza, Universidade Federal de Alfenas, Alfenas, Brazil
| | - Timothy A Batz
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, Indiana, USA
| | - Fábio M DaMatta
- Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Faculty of Natural Sciences, Ulm University, Ulm, Baden-Württemberg, Germany
| | - Scott A M McAdam
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, Indiana, USA
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19
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Nie ZF, Liao ZQ, Yao GQ, Tian XQ, Bi MH, Teixeira da Silva JA, Gao TP, Fang XW. Divergent stem hydraulic strategies of Caragana korshinskii resprouts following a disturbance. TREE PHYSIOLOGY 2022; 42:325-336. [PMID: 34387352 DOI: 10.1093/treephys/tpab108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
Resprouting plants are distributed in many vegetation communities worldwide. With increasing resprout age post-severe-disturbance, new stems grow rapidly at their early age, and decrease in their growth with gradually decreasing water status thereafter. However, there is little knowledge about how stem hydraulic strategies and anatomical traits vary post-disturbance. In this study, the stem water potential (Ψstem), maximum stem hydraulic conductivity (Kstem-max), water potential at 50% loss of hydraulic conductivity (Kstem P50) and anatomical traits of Caragana korshinkii resprouts were measured during a 1- to 13-year post-disturbance period. We found that the Kstem-max decreased with resprout age from 1-year-old resprouts (84.2 mol m-1 s-1 MPa-1) to 13-year-old resprouts (54.2 mol m-1 s-1 MPa-1) as a result of decreases in the aperture fraction (Fap) and the sum of aperture area on per unit intervessel wall area (Aap). The Kstem P50 of the resprouts decreased from 1-year-old resprouts (-1.8 MPa) to 13-year-old resprouts (-2.9 MPa) as a result of increases in vessel implosion resistance (t/b)2, wood density (WD), vessel grouping index (GI) and decreases in Fap and Aap. These shifts in hydraulic structure and function resulted in an age-based divergence in hydraulic strategies i.e., a change from an acquisitive strategy to a conservative strategy, with increasing resprout age post-disturbance.
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Affiliation(s)
- Zheng-Fei Nie
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Zhong-Qiang Liao
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Guang-Qian Yao
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Xue-Qian Tian
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Min-Hui Bi
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | | | - Tian-Peng Gao
- School of Biological and Environmental Engineering, Xi'an University, Xi'an 710065, China
| | - Xiang-Wen Fang
- State Key Laboratory of Grassland Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
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20
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Ganthaler A, Bär A, Dämon B, Losso A, Nardini A, Dullin C, Tromba G, von Arx G, Mayr S. Alpine dwarf shrubs show high proportions of nonfunctional xylem: Visualization and quantification of species-specific patterns. PLANT, CELL & ENVIRONMENT 2022; 45:55-68. [PMID: 34783044 DOI: 10.1111/pce.14226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 07/15/2021] [Accepted: 07/15/2021] [Indexed: 06/13/2023]
Abstract
Xylem conductive capacity is a key determinant of plant hydraulic function and intimately linked to photosynthesis and productivity, but can be impeded by temporary or permanent conduit dysfunctions. Here we show that persistent xylem dysfunctions in unstressed plants are frequent in Alpine dwarf shrubs and occur in various but species-specific cross-sectional patterns. Combined synchrotron micro-computed tomography (micro-CT) imaging, xylem staining, and flow measurements in saturated samples of six widespread Ericaceae species evidence a high proportion (19%-50%) of hydraulically nonfunctional xylem areas in the absence of drought stress, with regular distribution of dysfunctions between or within growth rings. Dysfunctions were only partly reversible and reduced the specific hydraulic conductivity to 1.38 to 3.57 ×10-4 m2 s-1 MPa-1 . Decommission of inner growth rings was clearly related to stem age and a higher vulnerability to cavitation of older rings, while the high proportion of nonfunctional conduits in each annual ring needs further investigations. The lower the xylem fraction contributing to the transport function, the higher was the hydraulic efficiency of conducting xylem areas. Improved understanding of the functional lifespan of xylem elements and the prevalence and nature of dysfunctions is critical to correctly assess structure-function relationships and whole-plant hydraulic strategies.
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Affiliation(s)
- Andrea Ganthaler
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Andreas Bär
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Birgit Dämon
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Adriano Losso
- Department of Botany, University of Innsbruck, Innsbruck, Austria
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
| | - Andrea Nardini
- Dipartimento di Scienze della Vita, Università di Trieste, Trieste, Italy
| | - Christian Dullin
- Elettra-Sincrotrone Trieste, Basovizza, Italy
- Institute for Diagnostic and Interventional Radiology, University Medical Center, Göttingen, Germany
- Max-Planck-Institute for Experimental Medicine, Göttingen, Germany
- Diagnostic and Interventional Radiology, University Hospital, Heidelberg, Germany
| | | | - Georg von Arx
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
| | - Stefan Mayr
- Department of Botany, University of Innsbruck, Innsbruck, Austria
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21
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Evans LS. Quantification of Eccentricity in Stems of Two Species of Purshia. WEST N AM NATURALIST 2021. [DOI: 10.3398/064.081.0410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Lance S. Evans
- Pfizer Laboratory, New York Botanical Garden, The Bronx, NY 10458
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22
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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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23
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Bera BK, Tzuk O, Bennett JJR, Meron E. Linking spatial self-organization to community assembly and biodiversity. eLife 2021; 10:e73819. [PMID: 34570698 PMCID: PMC8497052 DOI: 10.7554/elife.73819] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 09/19/2021] [Indexed: 11/29/2022] Open
Abstract
Temporal shifts to drier climates impose environmental stresses on plant communities that may result in community reassembly and threatened ecosystem services, but also may trigger self-organization in spatial patterns of biota and resources, which act to relax these stresses. The complex relationships between these counteracting processes - community reassembly and spatial self-organization - have hardly been studied. Using a spatio-temporal model of dryland plant communities and a trait-based approach, we study the response of such communities to increasing water-deficit stress. We first show that spatial patterning acts to reverse shifts from fast-growing species to stress-tolerant species, as well as to reverse functional-diversity loss. We then show that spatial self-organization buffers the impact of further stress on community structure. Finally, we identify multistability ranges of uniform and patterned community states and use them to propose forms of non-uniform ecosystem management that integrate the need for provisioning ecosystem services with the need to preserve community structure.
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Affiliation(s)
- Bidesh K Bera
- Department of Solar Energy and Environmental Physics, BIDR, Ben-Gurion University of the NegevSede Boqer CampusIsrael
| | - Omer Tzuk
- Physics Department, Ben-Gurion University of the NegevBeer ShevaIsrael
| | - Jamie JR Bennett
- Department of Solar Energy and Environmental Physics, BIDR, Ben-Gurion University of the NegevSede Boqer CampusIsrael
| | - Ehud Meron
- Department of Solar Energy and Environmental Physics, BIDR, Ben-Gurion University of the NegevSede Boqer CampusIsrael
- Physics Department, Ben-Gurion University of the NegevBeer ShevaIsrael
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24
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Chen YJ, Choat B, Sterck F, Maenpuen P, Katabuchi M, Zhang SB, Tomlinson KW, Oliveira RS, Zhang YJ, Shen JX, Cao KF, Jansen S. Hydraulic prediction of drought-induced plant dieback and top-kill depends on leaf habit and growth form. Ecol Lett 2021; 24:2350-2363. [PMID: 34409716 DOI: 10.1111/ele.13856] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 04/19/2021] [Accepted: 07/11/2021] [Indexed: 01/05/2023]
Abstract
Hydraulic failure caused by severe drought contributes to aboveground dieback and whole-plant death. The extent to which dieback or whole-plant death can be predicted by plant hydraulic traits has rarely been tested among species with different leaf habits and/or growth forms. We investigated 19 hydraulic traits in 40 woody species in a tropical savanna and their potential correlations with drought response during an extreme drought event during the El Niño-Southern Oscillation in 2015. Plant hydraulic trait variation was partitioned substantially by leaf habit but not growth form along a trade-off axis between traits that support drought tolerance versus avoidance. Semi-deciduous species and shrubs had the highest branch dieback and top-kill (complete aboveground death) among the leaf habits or growth forms. Dieback and top-kill were well explained by combining hydraulic traits with leaf habit and growth form, suggesting integrating life history traits with hydraulic traits will yield better predictions.
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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, China.,Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Yunnan, China.,Yuanjiang Savanna Ecosystem Research Station, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yuanjiang, Yunnan, China.,Forest Ecology and Forest Management Group, Wageningen University and Research, Wageningen, the Netherlands
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
| | - Frank Sterck
- Forest Ecology and Forest Management Group, Wageningen University and Research, Wageningen, the Netherlands
| | - Phisamai Maenpuen
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Masatoshi Katabuchi
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China
| | - Shu-Bin Zhang
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China.,Yuanjiang Savanna Ecosystem Research Station, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Yuanjiang, Yunnan, China
| | - Kyle W Tomlinson
- Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China
| | - Rafael S Oliveira
- Department of Plant Biology, Institute of Biology, CP6109, University of Campinas - UNICAMP, Campinas, São Paulo, Brazil
| | - Yong-Jiang Zhang
- School of Biology and Ecology, University of Maine, Orono, Maine, USA
| | - Jing-Xian Shen
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan, China.,Institute of Ecology and Geobotany, School of Ecology and Environmental Sciences, Yunnan University, Kunming, Yunnan, China
| | - Kun-Fang Cao
- State Key Laboratory for Conservation and Utilization of Agro-bioresources, Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, China
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Ulm, Germany
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25
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Chomicki G. Bringing Raunkiaer with plant architecture: unveiling the climatic drivers of architectural evolution in Euphorbia. THE NEW PHYTOLOGIST 2021; 231:910-912. [PMID: 34101184 DOI: 10.1111/nph.17446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Affiliation(s)
- Guillaume Chomicki
- Department of Animal and Plant Sciences, Alfred Denny Building, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
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26
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Anest A, Charles-Dominique T, Maurin O, Millan M, Edelin C, Tomlinson KW. Evolving the structure: climatic and developmental constraints on the evolution of plant architecture. A case study in Euphorbia. THE NEW PHYTOLOGIST 2021; 231:1278-1295. [PMID: 33629359 DOI: 10.1111/nph.17296] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 02/18/2021] [Indexed: 06/12/2023]
Abstract
Plant architecture strongly influences ecological performance, yet its role in plant evolution has not been explored in depth. By testing both phylogenetic and environmental signals, it is possible to separate architectural traits into four categories: development constraints (phylogenetic signal only); convergences (environmental dependency only); key confluences to the environmental driver (both); unknown (neither). We analysed the evolutionary history of the genus Euphorbia, a model clade with both high architectural diversity and a wide environmental range. We conducted comparative analyses of 193 Euphorbia species world-wide using 73 architectural traits, a dated phylogeny, and climate data. We identified 14 architectural types in Euphorbia based on trait combinations. We found 22 traits and three types representing convergences under climate groups, 21 traits and four types showing phylogenetic signal but no relation to climate, and 16 traits and five types with both climate and phylogenetic signals. Major drivers of architectural trait evolution likely include water stress in deserts (selected for succulence, continuous branching), frost disturbance in temperate systems (selected for simple, prostrate, short-lived shoots) and light competition (selected for arborescence). Simple architectures allowed resilience to disturbance, and frequent transitions into new forms. Complex architectures with functional specialisation developed under stable climates but have low evolvability.
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Affiliation(s)
- Artémis Anest
- Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, 666303, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | | | - Olivier Maurin
- Comparative Plant and Fungal Biology, Plant and Fungal Trees of Life, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AE, UK
| | - Mathieu Millan
- Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, Private Bag X3, WITS, 2050, South Africa
- Global Change Biology Group, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Claude Edelin
- French Institute of Pondicherry, No. 11, Post Box No. 33, Saint Louis Street, Pondicherry, 605 001, India
- UMR AMAP, CIRAD - TA A51/PS2, Montpellier Cedex 5, 34398, France
| | - Kyle W Tomlinson
- Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, 666303, China
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, 666303, China
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27
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Perspectives and design considerations of capillary-driven artificial trees for fast dewatering processes. Sci Rep 2021; 11:8631. [PMID: 33883623 PMCID: PMC8060284 DOI: 10.1038/s41598-021-88006-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 04/07/2021] [Indexed: 11/17/2022] Open
Abstract
Recent progresses on nanocapillary-driven water transport under metastable conditions have substantiated the potential of artificial trees for dewatering applications in a wide pressure range. This paper presents a comprehensive performance analysis of artificial trees encompassing the principle for negative capillary pressure generation; impacts of structural, compositional, and environmental conditions on dewatering performance; and design considerations. It begins by delineating functionalities of artificial trees for evaporation (leaves), conduction (xylem), and filtration (root) of water, in the analogy to natural trees. The analysis revealed that the magnitude of (negative) capillary pressure in the artificial leaves and xylem must be sufficiently large to overcome the osmotic pressure of feed at the root. The required magnitude can be reduced by increasing the osmotic pressure in the artificial xylem conduits, which reduces the risk of cavitation and subsequent blockage of water transport. However, a severe concentration polarization that can occur in long xylem conduits would negate such compensation effect of xylem osmotic pressure, leading to vapor pressure depression at the artificial leaves and therefore reduced dewatering rates. Enhanced Taylor dispersions by increasing xylem conduit diameters are found to alleviate the concentration polarization, allowing for water flux enhancement directly by increasing leaf-to-root membrane area ratio.
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28
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McElrone AJ, Manuck CM, Brodersen CR, Patakas A, Pearsall KR, Williams LE. Functional hydraulic sectoring in grapevines as evidenced by sap flow, dye infusion, leaf removal and micro-computed tomography. AOB PLANTS 2021; 13:plab003. [PMID: 33841756 PMCID: PMC8023307 DOI: 10.1093/aobpla/plab003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 01/08/2021] [Indexed: 05/24/2023]
Abstract
The supply of water to a plant canopy is dependent on the xylem pathway connecting roots to leaves. In some plants, sectored xylem pathways can restrict resource distribution, resulting in variable quality of organs in the shoots, yet little is known about the effects of sectoring in crop cultivars. In this study, we combined sap flow measurements and infusion of xylem-specific dyes to document functional conductive area and flow pathways from roots to shoots of 20-year-old Thompson Seedless and 8-year-old Chardonnay grapevines. Sap flow measurements and dye infusion demonstrated that water flowed predominantly in discrete xylem (visually identifiable from the trunk surface) sectors along the trunk axis, each supplying limited portions of the canopy. Functional conductive area in the trunk was proportional to that in the shoots even though sector size varied considerably between vines. Leaf area removal experiments further demonstrated sectoring in grapevines; sap flow decreased by >90 % in trunk sectors connected to excised shoots while it remained constant in trunk sectors supplying intact portions of the canopy. Despite the functional sectoring in grapevines, a high degree of interconnectivity of trunk xylem in the tangential direction was confirmed with synchrotron-based micro-computed tomography (microCT) and dye crossover infusion studies. Fruit attached to dyed canes was also similarly sectored; no clusters exhibited dye on non-dyed canes, while 97 % of clusters attached to dyed canes exhibited dye infusion. The dye travelled down the cluster rachis and appeared to accumulate at the pedicel/berry junction, but only on dyed canes. These findings suggest that xylem in grapevine trunks is integrated anatomically, but functions in a sectored manner due to high axial hydraulic conductivity. The functional sectoring of grapevine xylem documented here has important implications for management practices in vineyards and for fruit cluster uniformity within single grapevine.
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Affiliation(s)
- A J McElrone
- USDA-ARS, Crops Pathology and Genetics Research Unit, Davis, CA 95616, USA
- Department of Viticulture and Enology, University of California, Davis, CA 95616, USA
| | - C M Manuck
- USDA-ARS, Crops Pathology and Genetics Research Unit, Davis, CA 95616, USA
| | | | - A Patakas
- University of Ioannina, Ioannina, 451 10, Greece
| | - K R Pearsall
- Department of Viticulture and Enology, University of California, Davis, CA 95616, USA
| | - L E Williams
- Department of Viticulture and Enology, University of California, Davis, CA 95616, USA
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29
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Johnson KM, Brodersen C, Carins-Murphy MR, Choat B, Brodribb TJ. Xylem Embolism Spreads by Single-Conduit Events in Three Dry Forest Angiosperm Stems. PLANT PHYSIOLOGY 2020; 184:212-222. [PMID: 32581116 PMCID: PMC7479884 DOI: 10.1104/pp.20.00464] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 06/15/2020] [Indexed: 05/02/2023]
Abstract
Xylem cavitation resulting in air embolism is a major cause of plant death during drought, yet the spread of embolism throughout the plant water transport system is poorly understood. Our study used optical visualization and x-ray microcomputed tomography imaging to capture the spread of emboli in stems of three drought-resistant angiosperm trees: drooping she-oak (Allocasuarina verticillata), black wattle (Acacia mearnsii), and blue gum (Eucalyptus globulus). These species have similar degrees of xylem network connectivity (vessel grouping) with largely solitary vessels. The high temporal resolution of the optical vulnerability technique revealed that in current year branches, >80% of the cavitation events were discrete, temporally separated events in single vessels. This suggests that in xylem networks with low connectivity, embolism spread between conduits leading to multiple conduit cavitation events is uncommon. A. mearnsii showed both the highest number of multivessel cavitation events and the highest degree of vessel connectivity, suggesting a link between vessel arrangement and embolism spread. Knowledge of embolism spread will help us to uncover the links between xylem anatomy, arrangement, and the path of water flow in the xylem in diverse species to ultimately understand the drivers of cavitation and plant vulnerability to drought.
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Affiliation(s)
- Kate M Johnson
- Discipline of Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Craig Brodersen
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511
| | - Madeline R Carins-Murphy
- Discipline of Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Brendan Choat
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales 2750, Australia
| | - Timothy J Brodribb
- Discipline of Biological Sciences, School of Natural Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia
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30
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Morris H, Hietala AM, Jansen S, Ribera J, Rosner S, Salmeia KA, Schwarze FWMR. Using the CODIT model to explain secondary metabolites of xylem in defence systems of temperate trees against decay fungi. ANNALS OF BOTANY 2020; 125:701-720. [PMID: 31420666 PMCID: PMC7182590 DOI: 10.1093/aob/mcz138] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Accepted: 08/12/2019] [Indexed: 05/06/2023]
Abstract
BACKGROUND In trees, secondary metabolites (SMs) are essential for determining the effectiveness of defence systems against fungi and why defences are sometimes breached. Using the CODIT model (Compartmentalization of Damage/Dysfunction in Trees), we explain defence processes at the cellular level. CODIT is a highly compartmented defence system that relies on the signalling, synthesis and transport of defence compounds through a three-dimensional lattice of parenchyma against the spread of decay fungi in xylem. SCOPE The model conceptualizes 'walls' that are pre-formed, formed during and formed after wounding events. For sapwood, SMs range in molecular size, which directly affects performance and the response times in which they can be produced. When triggered, high-molecular weight SMs such as suberin and lignin are synthesized slowly (phytoalexins), but can also be in place at the time of wounding (phytoanticipins). In contrast, low-molecular weight phenolic compounds such as flavonoids can be manufactured de novo (phytoalexins) rapidly in response to fungal colonization. De novo production of SMs can be regulated in response to fungal pathogenicity levels. The protective nature of heartwood is partly based on the level of accumulated antimicrobial SMs (phytoanticipins) during the transitionary stage into a normally dead substance. Effectiveness against fungal colonization in heartwood is largely determined by the genetics of the host. CONCLUSION Here we review recent advances in our understanding of the role of SMs in trees in the context of CODIT, with emphasis on the relationship between defence, carbohydrate availability and the hydraulic system.We also raise the limitations of the CODIT model and suggest its modification, encompassing other defence theory concepts. We envisage the development of a new defence system that is modular based and incorporates all components (and organs) of the tree from micro- to macro-scales.
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Affiliation(s)
- Hugh Morris
- Laboratory for Cellulose & Wood Materials, Empa-Swiss Federal Laboratories for Materials Science and Technology, St. Gallen, Switzerland
| | - Ari M Hietala
- Norwegian Institute of Bioeconomy Research, Ås, Norway
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Ulm, Germany
| | - Javier Ribera
- Laboratory for Cellulose & Wood Materials, Empa-Swiss Federal Laboratories for Materials Science and Technology, St. Gallen, Switzerland
| | | | - Khalifah A Salmeia
- Laboratory of Advanced Fibers, Empa-Swiss Federal Laboratories for Materials Science and Technology, St. Gallen, Switzerland
| | - Francis W M R Schwarze
- Laboratory for Cellulose & Wood Materials, Empa-Swiss Federal Laboratories for Materials Science and Technology, St. Gallen, Switzerland
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31
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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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32
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Bouda M, Windt CW, McElrone AJ, Brodersen CR. In vivo pressure gradient heterogeneity increases flow contribution of small diameter vessels in grapevine. Nat Commun 2019; 10:5645. [PMID: 31822680 DOI: 10.17605/osf.io/ey2tj] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 11/19/2019] [Indexed: 05/26/2023] Open
Abstract
Leaves lose approximately 400 H2O molecules for every 1 CO2 gained during photosynthesis. Most long-distance water transport in plants, or xylem sap flow, serves to replace this water to prevent desiccation. Theory predicts that the largest vessels contribute disproportionately to overall sap flow because flow in pipe-like systems scales with the fourth power of radius. Here, we confront these theoretical flow predictions for a vessel network reconstructed from X-ray μCT imagery with in vivo flow MRI observations from the same sample of a first-year grapevine stem. Theoretical flow rate predictions based on vessel diameters are not supported. The heterogeneity of the vessel network gives rise to transverse pressure gradients that redirect flow from wide to narrow vessels, reducing the contribution of wide vessels to sap flow by 15% of the total. Our results call for an update of the current working model of the xylem to account for its heterogeneity.
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Affiliation(s)
- Martin Bouda
- School of Forestry & Environmental Studies, Yale University, 195 Prospect St., New Haven, CT, 06511, USA.
- Institute of Botany of the Czech Academy of Sciences, Zámek 1, 25243, Průhonice, Czech Republic.
| | - Carel W Windt
- IBG-2: Plant Sciences, Forschungszentrum Jülich, Leo Brandt Straße 1, 52428, Jülich, Germany
| | - Andrew J McElrone
- Department of Viticulture & Enology, University of California, 595 Hilgard Ln, Davis, CA, 95616, USA
- USDA-ARS, Crops Pathology and Genetics Research Unit, Davis, CA, USA
| | - Craig R Brodersen
- School of Forestry & Environmental Studies, Yale University, 195 Prospect St., New Haven, CT, 06511, USA
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33
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Bouda M, Windt CW, McElrone AJ, Brodersen CR. In vivo pressure gradient heterogeneity increases flow contribution of small diameter vessels in grapevine. Nat Commun 2019; 10:5645. [PMID: 31822680 PMCID: PMC6904565 DOI: 10.1038/s41467-019-13673-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 11/19/2019] [Indexed: 11/16/2022] Open
Abstract
Leaves lose approximately 400 H2O molecules for every 1 CO2 gained during photosynthesis. Most long-distance water transport in plants, or xylem sap flow, serves to replace this water to prevent desiccation. Theory predicts that the largest vessels contribute disproportionately to overall sap flow because flow in pipe-like systems scales with the fourth power of radius. Here, we confront these theoretical flow predictions for a vessel network reconstructed from X-ray μCT imagery with in vivo flow MRI observations from the same sample of a first-year grapevine stem. Theoretical flow rate predictions based on vessel diameters are not supported. The heterogeneity of the vessel network gives rise to transverse pressure gradients that redirect flow from wide to narrow vessels, reducing the contribution of wide vessels to sap flow by 15% of the total. Our results call for an update of the current working model of the xylem to account for its heterogeneity. Plants require long-distance water transport to avoid desiccation. Here, via μCT and MRI of grapevine stem, Bouda et al. show evidence of pressure gradient heterogeneity and flow redirection from wide to narrow vessels that suggests narrow vessels contribute more to xylem sap flow than previously appreciated.
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Affiliation(s)
- Martin Bouda
- School of Forestry & Environmental Studies, Yale University, 195 Prospect St., New Haven, CT, 06511, USA. .,Institute of Botany of the Czech Academy of Sciences, Zámek 1, 25243, Průhonice, Czech Republic.
| | - Carel W Windt
- IBG-2: Plant Sciences, Forschungszentrum Jülich, Leo Brandt Straße 1, 52428, Jülich, Germany
| | - Andrew J McElrone
- Department of Viticulture & Enology, University of California, 595 Hilgard Ln, Davis, CA, 95616, USA.,USDA-ARS, Crops Pathology and Genetics Research Unit, Davis, CA, USA
| | - Craig R Brodersen
- School of Forestry & Environmental Studies, Yale University, 195 Prospect St., New Haven, CT, 06511, USA
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34
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Continuum Modeling of Discrete Plant Communities: Why Does It Work and Why Is It Advantageous? MATHEMATICS 2019. [DOI: 10.3390/math7100987] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Understanding ecosystem response to drier climates calls for modeling the dynamics of dryland plant populations, which are crucial determinants of ecosystem function, as they constitute the basal level of whole food webs. Two modeling approaches are widely used in population dynamics, individual (agent)-based models and continuum partial-differential-equation (PDE) models. The latter are advantageous in lending themselves to powerful methodologies of mathematical analysis, but the question of whether they are suitable to describe small discrete plant populations, as is often found in dryland ecosystems, has remained largely unaddressed. In this paper, we first draw attention to two aspects of plants that distinguish them from most other organisms—high phenotypic plasticity and dispersal of stress-tolerant seeds—and argue in favor of PDE modeling, where the state variables that describe population sizes are not discrete number densities, but rather continuous biomass densities. We then discuss a few examples that demonstrate the utility of PDE models in providing deep insights into landscape-scale behaviors, such as the onset of pattern forming instabilities, multiplicity of stable ecosystem states, regular and irregular, and the possible roles of front instabilities in reversing desertification. We briefly mention a few additional examples, and conclude by outlining the nature of the information we should and should not expect to gain from PDE model studies.
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35
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Evans LS, Kharran TA, Pena I, Kitchen SG. Quantification of Eccentricity in Stems of Artemisia tridentata Nutt. WEST N AM NATURALIST 2019. [DOI: 10.3398/064.079.0312] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Lance S. Evans
- Laboratory of Plant Morphogenesis, Manhattan College, Bronx, NY 10471
| | | | - Ismael Pena
- Laboratory of Plant Morphogenesis, Manhattan College, Bronx, NY 10471
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McCulloh KA, Domec JC, Johnson DM, Smith DD, Meinzer FC. A dynamic yet vulnerable pipeline: Integration and coordination of hydraulic traits across whole plants. PLANT, CELL & ENVIRONMENT 2019; 42:2789-2807. [PMID: 31273812 DOI: 10.1111/pce.13607] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 07/01/2019] [Accepted: 07/02/2019] [Indexed: 06/09/2023]
Abstract
The vast majority of measurements in the field of plant hydraulics have been on small-diameter branches from woody species. These measurements have provided considerable insight into plant functioning, but our understanding of plant physiology and ecology would benefit from a broader view, because branch hydraulic properties are influenced by many factors. Here, we discuss the influence that other components of the hydraulic network have on branch vulnerability to embolism propagation. We also modelled the impact of changes in the ratio of root-to-leaf areas and soil texture on vulnerability to hydraulic failure along the soil-to-leaf continuum and showed that hydraulic function is better maintained through changes in root vulnerability and root-to-leaf area ratio than in branch vulnerability. Differences among species in the stringency with which they regulate leaf water potential and in reliance on stored water to buffer changes in water potential also affect the need to construct embolism resistant branches. Many approaches, such as measurements on fine roots, small individuals, combining sap flow and psychrometry techniques, and modelling efforts, could vastly improve our understanding of whole-plant hydraulic functioning. A better understanding of how traits are coordinated across the whole plant will improve predictions for plant function under future climate conditions.
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Affiliation(s)
| | - 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
| | - Daniel M Johnson
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, 30602, USA
| | - Duncan D Smith
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Frederick C Meinzer
- USDA Forest Service, Pacific Northwest Research Station, Corvallis, OR, 97331, USA
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37
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Wei L, Xu C, Jansen S, Zhou H, Christoffersen BO, Pockman WT, Middleton RS, Marshall JD, McDowell NG. A heuristic classification of woody plants based on contrasting shade and drought strategies. TREE PHYSIOLOGY 2019; 39:767-781. [PMID: 30715506 DOI: 10.1093/treephys/tpy146] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 11/21/2018] [Accepted: 12/19/2018] [Indexed: 06/09/2023]
Abstract
Woody plants vary in their adaptations to drought and shade. For a better prediction of vegetation responses to drought and shade within dynamic global vegetation models, it is critical to group species into functional types with similar adaptations. One of the key challenges is that the adaptations are generally determined by a large number of plant traits that may not be available for a large number of species. In this study, we present two heuristic woody plant groups that were separated using cluster analysis in a three-dimensional trait-environment space based on three key metrics for each species: mean xylem embolism resistance, shade tolerance and habitat aridity. The two heuristic groups separate these species into tolerators and avoiders. The tolerators either rely on their high embolism resistance to tolerate drought in arid habitats (e.g., Juniperus and Prunus) or rely on high shade tolerance to withstand shaded conditions in wet habitats (e.g., Picea, Abies and Acer). In contrast, all avoiders have low embolism resistance and low shade tolerance. In arid habitats, avoiders tend to minimize catastrophic embolism (e.g., most Pinus species) while in wet habitats, they may survive despite low shade tolerance (e.g., Betula, Populus, Alnus and Salix). Because our approach links traits to the environmental conditions, we expect it could be a promising framework for predicting changes in species composition, and therefore ecosystem function, under changing environmental conditions.
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Affiliation(s)
- Liang Wei
- Los Alamos National Laboratory, Earth and Environmental Sciences, Los Alamos, NM, USA
| | - Chonggang Xu
- Los Alamos National Laboratory, Earth and Environmental Sciences, Los Alamos, NM, USA
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm University, Albert-Einstein-Allee 11, Ulm, Germany
| | - Hang Zhou
- Descartes Labs, Inc., 1613 Paseo De Peralta Ste. 200, Santa Fe, NM, USA
- Department of Geography, University of Idaho, Moscow, ID, USA
| | - Bradley O Christoffersen
- Department of Biology and School of Earth, Environmental, and Marine Sciences, University of Texas Rio Grande Valley, Edinburg, TX, USA
| | - William T Pockman
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Richard S Middleton
- Los Alamos National Laboratory, Earth and Environmental Sciences, Los Alamos, NM, USA
| | - John D Marshall
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogmarksgränd, Umeå, Sweden
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38
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Brodersen CR, Roddy AB, Wason JW, McElrone AJ. Functional Status of Xylem Through Time. ANNUAL REVIEW OF PLANT BIOLOGY 2019; 70:407-433. [PMID: 30822114 DOI: 10.1146/annurev-arplant-050718-100455] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Water transport in vascular plants represents a critical component of terrestrial water cycles and supplies the water needed for the exchange of CO2 in the atmosphere for photosynthesis. Yet, many fundamental principles of water transport are difficult to assess given the scale and location of plant xylem. Here we review the mechanistic principles that underpin long-distance water transport in vascular plants, with a focus on woody species. We also discuss the recent development of noninvasive tools to study the functional status of xylem networks in planta. Limitations of current methods to detect drought-induced xylem blockages (e.g., embolisms) and quantify corresponding declines in sap flow, and the coordination of hydraulic dysfunction with other physiological processes are assessed. Future avenues of research focused on cross-validation of plant hydraulics methods are discussed, as well as a proposed fundamental shift in the theory and methodology used to characterize and measure plant water use.
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Affiliation(s)
- Craig R Brodersen
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA;
| | - Adam B Roddy
- School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA;
| | - Jay W Wason
- School of Forest Resources, University of Maine, Orono, Maine 04469, USA
| | - Andrew J McElrone
- US Department of Agriculture, Agricultural Research Service, Davis, California 95616, USA
- Department of Viticulture and Enology, University of California, Davis, California 95616, USA
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39
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Dong T, Duan B, Korpelainen H, Niinemets Ü, Li C. Asymmetric pruning reveals how organ connectivity alters the functional balance between leaves and roots of Chinese fir. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:1941-1953. [PMID: 30689933 DOI: 10.1093/jxb/erz013] [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: 09/16/2018] [Accepted: 01/04/2019] [Indexed: 06/09/2023]
Abstract
The functional balance between leaves and roots is believed to be mediated by the specific location of shoots and roots, i.e. differences in transport distances and degrees of organ connectivity. However, it remains unknown whether the adaptive responses of trees to biomass removal depend on the relative orientation of leaf and root pruning. Here, we applied five pruning treatments to saplings of Cunninghamia lanceolata (Chinese fir) under field and glasshouse conditions, namely no pruning (control), half of lateral branches pruned, half of lateral roots pruned, half of the branches and roots pruned on the same side of the plant, and half of the branches and roots pruned on opposite sides of the plant. The effects of pruning on the growth, carbon storage and allocation, and physiology of leaves and fine roots on the same and opposite sides of the plant were investigated. Compared with the effect of root-pruning on leaves, fine roots were more limited by carbon availability and their physiological activity was more strongly reduced by shoot pruning, especially when branches on the same side of the plant were removed. Pruning of branches and roots on the opposite side of the plant resulted in the lowest carbon assimilation rates and growth among all treatments. The results of a stable-isotope labeling indicated that less C was distributed to fine roots from the leaves on the opposite side of the plant compared to those on the same side, but N allocation from roots to leaves depended less on the relative root and leaf orientation. The results collectively indicate that the functional responses of C. lanceolata to pruning are not only determined by the source-sink balance model but are also related to interactions between leaves and fine roots. We argue that the connectivity among lateral branches and roots depends on their relative orientation, which is therefore critical for the functional balance between leaves and fine roots.
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Affiliation(s)
- Tingfa Dong
- Key Laboratory of Southwest China Wildlife Resources Conservation, Ministry of Education, and College of Life Sciences, China West Normal University, Nanchong, Sichuan, China
| | - Baoli Duan
- Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China
| | - Helena Korpelainen
- Department of Agricultural Sciences, Viikki Plant Science Centre, University of Helsinki, Finland
| | - Ülo Niinemets
- Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi, Tartu, Estonia
- Estonian Academy of Sciences, Kohtu, Tallinn, Estonia
| | - Chunyang Li
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
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40
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Pratt RB, Jacobsen AL. Identifying which conduits are moving water in woody plants: a new HRCT-based method. TREE PHYSIOLOGY 2018; 38:1200-1212. [PMID: 29660094 DOI: 10.1093/treephys/tpy034] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Accepted: 03/07/2018] [Indexed: 06/08/2023]
Abstract
In vivo imaging methods are useful for examination of plant vascular tissues, particularly in the identification of fluid vs gas-filled conduits; however, these methods may not allow for the simple identification of conductive conduits. Our aim in the present study was to develop a method that would allow for the in vivo identification of conductive conduits. Intact plants and segments of grapevine (Vitis vinifera L.) and intact American chestnut (Castanea dentata (Marshall) Borkh.) saplings were examined. We found that iohexol, a water soluble iodine-rich molecule, was a useful contrast agent. We also stained the xylem of segments and gas- dried samples to compare between intact scans and excised segments. Iohexol could be readily fed through cut roots or stems into the transpiration stream, was successfully transported through the xylem and marked conductive vessels within high-resolution computed tomography (HRCT) scans. Iohexol results were comparable to those obtained by staining cut segments, with iohexol detecting greater numbers of smaller conduits in some samples. Samples contained gas-filled conduits, as well as both conductive (containing iohexol tracer) and non-conductive (no iohexol tracer) fluid-filled vessels. Fluid-filled non-conductive vessels were likely still developing or were not connected to the sap stream by a low resistance pathway. We found minimal differences between intact and excised segments other than excision-related dilution of iohexol. Both vessels and vasicentric tracheids were filled with iohexol in chestnut, providing a new tool to study the functions of these different cell types. The use of iohexol as a tracer to identify conductive vessels may greatly improve the utility of HRCT as a tool in the study of plant hydraulic function. Future studies using HRCT will likely need to incorporate conductive vessel markers or controls into experiments due to the presence of non-conductive fluid-filled vessels within the xylem.
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Affiliation(s)
- R Brandon Pratt
- Department of Biology, California State University, Bakersfield, 9001 Stockdale Hwy, Bakersfield, CA, USA
| | - Anna L Jacobsen
- Department of Biology, California State University, Bakersfield, 9001 Stockdale Hwy, Bakersfield, CA, USA
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41
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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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42
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Lehnebach R, Beyer R, Letort V, Heuret P. The pipe model theory half a century on: a review. ANNALS OF BOTANY 2018; 121:773-795. [PMID: 29370362 PMCID: PMC5906905 DOI: 10.1093/aob/mcx194] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 11/28/2017] [Indexed: 05/12/2023]
Abstract
Background More than a half century ago, Shinozaki et al. (Shinozaki K, Yoda K, Hozumi K, Kira T. 1964a. A quantitative analysis of plant form - the pipe model theory. I. Basic analyses. Japanese Journal of Ecology B: 97-105) proposed an elegant conceptual framework, the pipe model theory (PMT), to interpret the observed linear relationship between the amount of stem tissue and corresponding supported leaves. The PMT brought a satisfactory answer to two vividly debated problems that were unresolved at the moment of its publication: (1) What determines tree form and which rules drive biomass allocation to the foliar versus stem compartments in plants? (2) How can foliar area or mass in an individual plant, in a stand or at even larger scales be estimated? Since its initial formulation, the PMT has been reinterpreted and used in applications, and has undoubtedly become an important milestone in the mathematical interpretation of plant form and functioning. Scope This article aims to review the PMT by going back to its initial formulation, stating its explicit and implicit properties and discussing them in the light of current biological knowledge and experimental evidence in order to identify the validity and range of applicability of the theory. We also discuss the use of the theory in tree biomechanics and hydraulics as well as in functional-structural plant modelling. Conclusions Scrutinizing the PMT in the light of modern biological knowledge revealed that most of its properties are not valid as a general rule. The hydraulic framework derived from the PMT has attracted much more attention than its mechanical counterpart and implies that only the conductive portion of a stem cross-section should be proportional to the supported foliage amount rather than the whole of it. The facts that this conductive portion is experimentally difficult to measure and varies with environmental conditions and tree ontogeny might cause the commonly reported non-linear relationships between foliage and stem metrics. Nevertheless, the PMT can still be considered as a portfolio of properties providing a unified framework to integrate and analyse functional-structural relationships.
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Affiliation(s)
- Romain Lehnebach
- Centre de coopération Internationale de la Recherche Agronomique pour le Développement (CIRAD), UMR Amap, Kourou, France
- Botany and Modelling of Plant Architecture and Vegetation (Amap), Université Montpellier, CIRAD, CNRS, INRA, IRD, Montpellier, France
| | - Robert Beyer
- Laboratory of Mathematics in Interaction with Computer Science (MICS), CentraleSupélec, France
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Véronique Letort
- Laboratory of Mathematics in Interaction with Computer Science (MICS), CentraleSupélec, France
| | - Patrick Heuret
- Institut National de la Recherche Agronomique (INRA), UMR Ecofog, Kourou, France
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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: 14] [Impact Index Per Article: 2.3] [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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Abstract
Senescence, an organismal performance decline with age, has historically been considered a universal phenomenon by evolutionary biologists and zoologist. Yet, increasing fertility and survival with age are nothing new to plant ecologists, among whom it is common knowledge that senescence is not universal. Recently, these two realities have come into a confrontation, begging for the rephrasing of the classical question that has led ageing research for decades: “why do we senesce?” to a more practical “what are the mechanisms by which some organisms escape from senescence?” Plants are amenable to examining this question because of their rich repertoire of life history strategies. These include the existence of permanent seed banks, vegetative dormancy and ability to produce clones, among others. Here, I use a large number of high resolution demographic models from 181 species that reflect life history strategies and their trade-offs among herbaceous perennials, succulents and shrubs measured under field conditions worldwide to examine whether senescence rates of ramets from clonal plants differ from those of whole plants reproducing either strictly sexually, or with a combination of sexual and clonal mechanisms. Contrary to the initial expectation from the mutation accumulation theory of senescence, ramets of clonal plants were more likely to exhibit senescence than those species employing sexual reproduction. I discuss why these comparisons between ramets and genets are useful, as well as its implications and future directions for ageing research.
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Affiliation(s)
- Roberto Salguero-Gómez
- Department of Zoology, University of Oxford, New Radcliffe House, Radcliffe Observatory Quarter, Oxford, OX2 6GG UK
- Centre of Excellence in Environmental Decisions, University of Queensland, St Lucia, QLD 4072 Australia
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Morris H, Brodersen C, Schwarze FWMR, Jansen S. The Parenchyma of Secondary Xylem and Its Critical Role in Tree Defense against Fungal Decay in Relation to the CODIT Model. FRONTIERS IN PLANT SCIENCE 2016; 7:1665. [PMID: 27881986 PMCID: PMC5101214 DOI: 10.3389/fpls.2016.01665] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 10/24/2016] [Indexed: 05/22/2023]
Abstract
This review examines the roles that ray and axial parenchyma (RAP) plays against fungal pathogens in the secondary xylem of wood within the context of the CODIT model (Compartmentalization of Decay in Trees), a defense concept first conceived in the early 1970s by Alex Shigo. This model, simplistic in its design, shows how a large woody perennial is highly compartmented. Anatomical divisions in place at the time of infection or damage, (physical defense) alongside the 'active' response by the RAP during and after wounding work together in forming boundaries that function to restrict air or decay spread. The living parenchyma cells play a critical role in all of the four walls (differing anatomical constructs) that the model comprises. To understand how living cells in each of the walls of CODIT cooperate, we must have a clear vision of their complex interconnectivity from a three-dimensional perspective, along with knowledge of the huge variation in ray parenchyma (RP) and axial parenchyma (AP) abundance and patterns. Crucial patterns for defense encompass the symplastic continuum between both RP and AP and the dead tissues, with the latter including the vessel elements, libriform fibers, and imperforate tracheary elements (i.e., vasicentric and vascular tracheids). Also, the heartwood, a chemically altered antimicrobial non-living substance that forms the core of many trees, provides an integral part of the defense system. In the heartwood, dead RAP can play an important role in defense, depending on the genetic constitution of the species. Considering the array of functions that RAP are associated with, from capacitance, through to storage, and long-distance water transport, deciding how their role in defense fits into this suite of functions is a challenge for plant scientists, and likely depends on a range of factors. Here, we explore the important role of RAP in defense against fungal pathogens and the trade-offs involved from a viewpoint for structure-function relations, while also examining how fungi can breach the defense system using an array of enzymes in conjunction with the physically intrusive hyphae.
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Affiliation(s)
- Hugh Morris
- Institute of Systematic Botany and Ecology, Ulm UniversityUlm, Germany
| | - Craig Brodersen
- School of Forestry and Environmental Studies, Yale University, New HavenCT, USA
| | - Francis W. M. R. Schwarze
- Laboratory for Applied Wood Materials, Empa-Swiss Federal Laboratories for Materials Testing and ResearchSt. Gallen, Switzerland
| | - Steven Jansen
- Institute of Systematic Botany and Ecology, Ulm UniversityUlm, Germany
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Wang YJ, Bai YF, Zeng SQ, Yao B, Wang W, Luo FL. Heterogeneous water supply affects growth and benefits of clonal integration between co-existing invasive and native Hydrocotyle species. Sci Rep 2016; 6:29420. [PMID: 27439691 PMCID: PMC4954970 DOI: 10.1038/srep29420] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 06/17/2016] [Indexed: 11/09/2022] Open
Abstract
Spatial patchiness and temporal variability in water availability are common in nature under global climate change, which can remarkably influence adaptive responses of clonal plants, i.e. clonal integration (translocating resources between connected ramets). However, little is known about the effects of spatial patchiness and temporal heterogeneity in water on growth and clonal integration between congeneric invasive and native Hydrocotyle species. In a greenhouse experiment, we subjected severed or no severed (intact) fragments of Hydrocotyle vulgaris, a highly invasive species in China, and its co-existing, native congener H. sibthorpioides to different spatial patchiness (homogeneous and patchy) and temporal interval (low and high interval) in water supply. Clonal integration had significant positive effects on growth of both species. In the homogeneous water conditions, clonal integration greatly improved the growth in fragments of both species under low interval in water. However, in the patchy water conditions, clonal integration significantly increased growth in both ramets and fragments of H. vulgaris under high interval in water. Therefore, spatial patchiness and temporal interval in water altered the effects of clonal integration of both species, especially for H. vulgaris. The adaptation of H. vulgaris might lead to invasive growth and potential spread under the global water variability.
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Affiliation(s)
- Yong-Jian Wang
- College of Horticulture &Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China
| | - Yun-Fei Bai
- College of Life Science &Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Shi-Qi Zeng
- College of Life Science &Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Bin Yao
- College of Life Science &Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Wen Wang
- College of Life Science &Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Fang-Li Luo
- School of Nature Conservation, Beijing Forestry University, Beijing 100083, China
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Brodersen CR, Rico C, Guenni O, Pittermann J. Embolism spread in the primary xylem of Polystichum munitum: implications for water transport during seasonal drought. PLANT, CELL & ENVIRONMENT 2016; 39:338-346. [PMID: 26227010 DOI: 10.1111/pce.12618] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 07/19/2015] [Accepted: 07/21/2015] [Indexed: 06/04/2023]
Abstract
Xylem network structure and function have been characterized for many woody plants, but less is known about fern xylem, particularly in species endemic to climates where water is a limiting resource for months at a time. We characterized seasonal variability in soil moisture and frond water status in a common perennial fern in the redwood understory of a costal California, and then investigated the consequences of drought-induced embolism on vascular function. Seasonal variability in air temperature and soil water content was minimal, and frond water potential declined slowly over the observational period. Our data show that Polystichum munitum was protected from significant drought-induced hydraulic dysfunction during this growing season because of a combination of cavitation resistant conduits (Air-seeding threshold (ASP) = -1.53 MPa; xylem pressure inducing 50% loss of hydraulic conductivity (P50 ) = -3.02 MPa) and a soil with low moisture variability. High resolution micro-computed tomography (MicroCT) imaging revealed patterns of embolism formation in vivo for the first time in ferns providing insight into the functional status of the xylem network under drought conditions. Together with stomatal conductance measurements, these data suggest that P. munitum is adapted to tolerate drier conditions than what was observed during the growing season.
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Affiliation(s)
- Craig R Brodersen
- School of Forestry and Environmental Studies, Yale University, New Haven, CT, 06511, USA
| | | | - Orlando Guenni
- Universidad Central de Venezuela, Facultad de Agronomía, Instituto de Botánica Agrícola, Maracay, 2101, Venezuela
| | - Jarmila Pittermann
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, 95064, USA
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Pattern formation – A missing link in the study of ecosystem response to environmental changes. Math Biosci 2016; 271:1-18. [DOI: 10.1016/j.mbs.2015.10.015] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 10/17/2015] [Accepted: 10/23/2015] [Indexed: 11/18/2022]
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Götmark F, Götmark E, Jensen AM. Why Be a Shrub? A Basic Model and Hypotheses for the Adaptive Values of a Common Growth Form. FRONTIERS IN PLANT SCIENCE 2016; 7:1095. [PMID: 27507981 PMCID: PMC4961008 DOI: 10.3389/fpls.2016.01095] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 07/11/2016] [Indexed: 05/08/2023]
Abstract
Shrubs are multi-stemmed short woody plants, more widespread than trees, important in many ecosystems, neglected in ecology compared to herbs and trees, but currently in focus due to their global expansion. We present a novel model based on scaling relationships and four hypotheses to explain the adaptive significance of shrubs, including a review of the literature with a test of one hypothesis. Our model describes advantages for a small shrub compared to a small tree with the same above-ground woody volume, based on larger cross-sectional stem area, larger area of photosynthetic tissue in bark and stem, larger vascular cambium area, larger epidermis (bark) area, and larger area for sprouting, and faster production of twigs and canopy. These components form our Hypothesis 1 that predicts higher growth rate for a small shrub than a small tree. This prediction was supported by available relevant empirical studies (14 publications). Further, a shrub will produce seeds faster than a tree (Hypothesis 2), multiple stems in shrubs insure future survival and growth if one or more stems die (Hypothesis 3), and three structural traits of short shrub stems improve survival compared to tall tree stems (Hypothesis 4)-all hypotheses have some empirical support. Multi-stemmed trees may be distinguished from shrubs by more upright stems, reducing bending moment. Improved understanding of shrubs can clarify their recent expansion on savannas, grasslands, and alpine heaths. More experiments and other empirical studies, followed by more elaborate models, are needed to understand why the shrub growth form is successful in many habitats.
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Affiliation(s)
- Frank Götmark
- Department of Biological and Environmental Sciences, University of GothenburgGöteborg, Sweden
- *Correspondence: Frank Götmark
| | - Elin Götmark
- Mathematical Sciences, Chalmers University of Technology and University of GothenburgGöteborg, Sweden
| | - Anna M. Jensen
- Department of Forestry and Wood Technology, Linnaeus UniversityVäxjö, Sweden
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