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Eisenring M, Gessler A, Frei ER, Glauser G, Kammerer B, Moor M, Perret-Gentil A, Wohlgemuth T, Gossner MM. Legacy effects of premature defoliation in response to an extreme drought event modulate phytochemical profiles with subtle consequences for leaf herbivory in European beech. THE NEW PHYTOLOGIST 2024; 242:2495-2509. [PMID: 38641748 DOI: 10.1111/nph.19721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 03/13/2024] [Indexed: 04/21/2024]
Abstract
Extreme droughts can have long-lasting effects on forest community dynamics and species interactions. Yet, our understanding of how drought legacy modulates ecological relationships is just unfolding. We tested the hypothesis that leaf chemistry and herbivory show long-term responses to premature defoliation caused by an extreme drought event in European beech (Fagus sylvatica L.). For two consecutive years after the extreme European summer drought in 2018, we collected leaves from the upper and lower canopy of adjacently growing drought-stressed and unstressed trees. Leaf chemistry was analyzed and leaf damage by different herbivore-feeding guilds was quantified. We found that drought had lasting impacts on leaf nutrients and on specialized metabolomic profiles. However, drought did not affect the primary metabolome. Drought-related phytochemical changes affected damage of leaf-chewing herbivores whereas damage caused by other herbivore-feeding guilds was largely unaffected. Drought legacy effects on phytochemistry and herbivory were often weaker than between-year or between-canopy strata variability. Our findings suggest that a single extreme drought event bears the potential to long-lastingly affect tree-herbivore interactions. Drought legacy effects likely become more important in modulating tree-herbivore interactions since drought frequency and severity are projected to globally increase in the coming decades.
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Affiliation(s)
- Michael Eisenring
- Forest Health & Biotic Interactions, Swiss Federal Research Institute WSL, Birmensdorf, 8903, Switzerland
| | - Arthur Gessler
- Department of Environmental Systems Science, Institute of Terrestrial Ecosystems, ETH Zurich, Zürich, 8092, Switzerland
- Forest Dynamics, Swiss Federal Research Institute WSL, Birmensdorf, 8903, Switzerland
| | - Esther R Frei
- Forest Dynamics, Swiss Federal Research Institute WSL, Birmensdorf, 8903, Switzerland
- WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, Davos, 7260, Switzerland
- Climate Change and Extremes in Alpine Regions Research Centre CERC, Davos, 7260, Switzerland
| | - Gaétan Glauser
- Neuchâtel Platform of Analytical Chemistry, University of Neuchâtel, Neuchâtel, 2000, Switzerland
| | - Bernd Kammerer
- Core Facility Metabolomics, Albert-Ludwigs-University Freiburg, Freiburg, 79014, Germany
| | - Maurice Moor
- Forest Health & Biotic Interactions, Swiss Federal Research Institute WSL, Birmensdorf, 8903, Switzerland
| | - Anouchka Perret-Gentil
- Forest Health & Biotic Interactions, Swiss Federal Research Institute WSL, Birmensdorf, 8903, Switzerland
| | - Thomas Wohlgemuth
- Forest Dynamics, Swiss Federal Research Institute WSL, Birmensdorf, 8903, Switzerland
| | - Martin M Gossner
- Forest Health & Biotic Interactions, Swiss Federal Research Institute WSL, Birmensdorf, 8903, Switzerland
- Department of Environmental Systems Science, Institute of Terrestrial Ecosystems, ETH Zurich, Zürich, 8092, Switzerland
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2
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Yao Y, Xia L, Yang L, Liu R, Zhang S. Drought responses and carbon allocation strategies of poplar with different leaf maturity. PHYSIOLOGIA PLANTARUM 2024; 176:e14224. [PMID: 38389291 DOI: 10.1111/ppl.14224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 02/08/2024] [Indexed: 02/24/2024]
Abstract
Leaf characteristics can reflect the adaptation of trees to drought stress. However, the effect of leaf maturity on drought stress has been neglected, leading to uncertainty in inferring individual tree responses to drought from leaves. The allocation strategy of photosynthetic carbon between leaf organs (fully expanded young and old leaves) under drought stress remains unclear. Poplar is a diverse and widespread tree species in arid and semi-arid regions. Here, three poplar genotypes (Populus cathayana, P. × euramericana 'Nanlin 895', and P. alba × P. tremula var. glandulosa) were selected and exposed to different watering regimes. The responses and carbon allocation strategies of leaves with different maturity to drought were investigated using a combination of leaf traits and 13 C pulse labelling technique. The results showed that (1) fully expanded young leaves had better osmotic regulation and antioxidant capacity than aged leaves under drought stress. (2) Aged leaves acted as a carbon source during water deficit, where their photosynthetic products were transferred and supplied to upper young leaves to promote stronger photosynthesis in young leaves to acquire resources for tree growth. This study highlights that the effect of leaf maturity should be considered in the future when investigating the effects of drought on woody plants, especially for continuously growing tree species. Therefore, our study not only demonstrates the existence of leaf-age-dependent responses to drought in poplar but also provides new insights into carbon allocation at the leaf level.
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Affiliation(s)
- Yuan Yao
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Linchao Xia
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Le Yang
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Ruixuan Liu
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Sheng Zhang
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
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3
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Hikino K, Danzberger J, Riedel VP, Hesse BD, Hafner BD, Gebhardt T, Rehschuh R, Ruehr NK, Brunn M, Bauerle TL, Landhäusser SM, Lehmann MM, Rötzer T, Pretzsch H, Buegger F, Weikl F, Pritsch K, Grams TEE. Dynamics of initial carbon allocation after drought release in mature Norway spruce-Increased belowground allocation of current photoassimilates covers only half of the carbon used for fine-root growth. GLOBAL CHANGE BIOLOGY 2022; 28:6889-6905. [PMID: 36039835 DOI: 10.1111/gcb.16388] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 07/02/2022] [Indexed: 06/15/2023]
Abstract
After drought events, tree recovery depends on sufficient carbon (C) allocation to the sink organs. The present study aimed to elucidate dynamics of tree-level C sink activity and allocation of recent photoassimilates (Cnew ) and stored C in c. 70-year-old Norway spruce (Picea abies) trees during a 4-week period after drought release. We conducted a continuous, whole-tree 13 C labeling in parallel with controlled watering after 5 years of experimental summer drought. The fate of Cnew to growth and CO2 efflux was tracked along branches, stems, coarse- and fine roots, ectomycorrhizae and root exudates to soil CO2 efflux after drought release. Compared with control trees, drought recovering trees showed an overall 6% lower C sink activity and 19% less allocation of Cnew to aboveground sinks, indicating a low priority for aboveground sinks during recovery. In contrast, fine-root growth in recovering trees was seven times greater than that of controls. However, only half of the C used for new fine-root growth was comprised of Cnew while the other half was supplied by stored C. For drought recovery of mature spruce trees, in addition to Cnew , stored C appears to be critical for the regeneration of the fine-root system and the associated water uptake capacity.
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Affiliation(s)
- Kyohsuke Hikino
- Professorship for Land Surface-Atmosphere Interactions, Ecophysiology of Plants, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Jasmin Danzberger
- Institute of Biochemical Plant Pathology, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - Vincent P Riedel
- Professorship for Land Surface-Atmosphere Interactions, Ecophysiology of Plants, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Benjamin D Hesse
- Professorship for Land Surface-Atmosphere Interactions, Ecophysiology of Plants, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Benjamin D Hafner
- School of Integrative Plant Science, Cornell University, Ithaca, New York, USA
| | - Timo Gebhardt
- Professorship for Land Surface-Atmosphere Interactions, Ecophysiology of Plants, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Romy Rehschuh
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research-Atmospheric Environmental Research (KIT/IMK-IFU), Garmisch-Partenkirchen, Germany
- Institute of General Ecology and Environmental Protection, Technische Universität Dresden, Pienner Str. 7, Tharandt, 01737, Germany
| | - Nadine K Ruehr
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research-Atmospheric Environmental Research (KIT/IMK-IFU), Garmisch-Partenkirchen, Germany
| | - Melanie Brunn
- Institute for Environmental Sciences, University Koblenz-Landau, Landau, Germany
| | - Taryn L Bauerle
- School of Integrative Plant Science, Cornell University, Ithaca, New York, USA
| | - Simon M Landhäusser
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
| | - Marco M Lehmann
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Forest Dynamics, Birmensdorf, Switzerland
| | - Thomas Rötzer
- Forest Growth and Yield Science, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Hans Pretzsch
- Forest Growth and Yield Science, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Franz Buegger
- Institute of Biochemical Plant Pathology, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - Fabian Weikl
- Professorship for Land Surface-Atmosphere Interactions, Ecophysiology of Plants, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
- Institute of Biochemical Plant Pathology, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - Karin Pritsch
- Institute of Biochemical Plant Pathology, Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Neuherberg, Germany
| | - Thorsten E E Grams
- Professorship for Land Surface-Atmosphere Interactions, Ecophysiology of Plants, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
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Fernández de Simón B, Cadahía E, Aranda I. Aerial and underground organs display specific metabolic strategies to cope with water stress under rising atmospheric CO 2 in Fagus sylvatica L. PHYSIOLOGIA PLANTARUM 2022; 174:e13711. [PMID: 35570621 PMCID: PMC9321914 DOI: 10.1111/ppl.13711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 04/26/2022] [Indexed: 06/15/2023]
Abstract
Beech is known to be a moderately drought-sensitive tree species, and future increases in atmospheric concentrations of CO2 ([CO2 ]) could influence its ecological interactions, also with changes at the metabolic level. The metabolome of leaves and roots of drought-stressed beech seedlings grown under two different [CO2 ] (400 (aCO2 ) and 800 (eCO2 ) ppm) was analyzed together with gas exchange parameters and water status. Water stress estimated from predawn leaf water potential (Ψpd ) was similar under both [CO2 ], although eCO2 had a positive impact on net photosynthesis and intrinsic water use efficiency. The aerial and underground organs showed different metabolomes. Leaves mainly stored C metabolites, while those of N and P accumulated differentially in roots. Drought triggered the proline and N-rich amino acids biosynthesis in roots through the activation of arginine and proline pathways. Besides the TCA cycle, polyols and soluble sugar biosynthesis were activated in roots, with no clear pattern seen in the leaves, prioritizing the root functioning as metabolites sink. eCO2 slightly altered this metabolic acclimation to drought, reflecting mitigation of its effect. The leaves showed only minor changes, investing C surplus in secondary metabolites and malic acid. The TCA cycle metabolites and osmotically active substances increased in roots, but many other metabolites decreased as if the water stress was dampened. Above- and belowground plant metabolomes were differentially affected by two drivers of climate change, water scarcity and high [CO2 ], showing different chemical responsiveness that could modulate the tree adaptation to future climatic scenarios.
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Affiliation(s)
- Brígida Fernández de Simón
- Grupo de Ecología Funcional de Especies ForestalesCentro de Investigacion Forestal (CIFOR‐INIA) CSICMadridSpain
| | - Estrella Cadahía
- Grupo de Ecología Funcional de Especies ForestalesCentro de Investigacion Forestal (CIFOR‐INIA) CSICMadridSpain
| | - Ismael Aranda
- Grupo de Ecología Funcional de Especies ForestalesCentro de Investigacion Forestal (CIFOR‐INIA) CSICMadridSpain
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5
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Hikino K, Danzberger J, Riedel VP, Rehschuh R, Ruehr NK, Hesse BD, Lehmann MM, Buegger F, Weikl F, Pritsch K, Grams TEE. High resilience of carbon transport in long-term drought-stressed mature Norway spruce trees within 2 weeks after drought release. GLOBAL CHANGE BIOLOGY 2022; 28:2095-2110. [PMID: 34927319 DOI: 10.1111/gcb.16051] [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: 06/08/2021] [Accepted: 11/29/2021] [Indexed: 06/14/2023]
Abstract
Under ongoing global climate change, drought periods are predicted to increase in frequency and intensity in the future. Under these circumstances, it is crucial for tree's survival to recover their restricted functionalities quickly after drought release. To elucidate the recovery of carbon (C) transport rates in c. 70-year-old Norway spruce (Picea abies [L.] KARST.) after 5 years of recurrent summer droughts, we conducted a continuous whole-tree 13 C labeling experiment in parallel with watering. We determined the arrival time of current photoassimilates in major C sinks by tracing the 13 C label in stem and soil CO2 efflux, and tips of living fine roots. In the first week after watering, aboveground C transport rates (CTR) from crown to trunk base were still 50% lower in previously drought-stressed trees (0.16 ± 0.01 m h-1 ) compared to controls (0.30 ± 0.06 m h-1 ). Conversely, CTR below ground, that is, from the trunk base to soil CO2 efflux were already similar between treatments (c. 0.03 m h-1 ). Two weeks after watering, aboveground C transport of previously drought-stressed trees recovered to the level of the controls. Furthermore, regrowth of water-absorbing fine roots upon watering was supported by faster incorporation of 13 C label in previously drought-stressed (within 12 ± 10 h upon arrival at trunk base) compared to control trees (73 ± 10 h). Thus, the whole-tree C transport system from the crown to soil CO2 efflux fully recovered within 2 weeks after drought release, and hence showed high resilience to recurrent summer droughts in mature Norway spruce forests. This high resilience of the C transport system is an important prerequisite for the recovery of other tree functionalities and productivity.
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Affiliation(s)
- Kyohsuke Hikino
- Technical University of Munich (TUM), TUM School of Life Sciences, Land Surface-Atmosphere Interactions, Ecophysiology of Plants, Freising, Germany
| | - Jasmin Danzberger
- Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Institute of Biochemical Plant Pathology, Neuherberg, Germany
| | - Vincent P Riedel
- Technical University of Munich (TUM), TUM School of Life Sciences, Land Surface-Atmosphere Interactions, Ecophysiology of Plants, Freising, Germany
| | - Romy Rehschuh
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research-Atmospheric Environmental Research (KIT/IMK-IFU), Garmisch-Partenkirchen, Germany
| | - Nadine K Ruehr
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research-Atmospheric Environmental Research (KIT/IMK-IFU), Garmisch-Partenkirchen, Germany
| | - Benjamin D Hesse
- Technical University of Munich (TUM), TUM School of Life Sciences, Land Surface-Atmosphere Interactions, Ecophysiology of Plants, Freising, Germany
| | - Marco M Lehmann
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Forest Dynamics, Birmensdorf, Switzerland
| | - Franz Buegger
- Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Institute of Biochemical Plant Pathology, Neuherberg, Germany
| | - Fabian Weikl
- Technical University of Munich (TUM), TUM School of Life Sciences, Land Surface-Atmosphere Interactions, Ecophysiology of Plants, Freising, Germany
- Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Institute of Biochemical Plant Pathology, Neuherberg, Germany
| | - Karin Pritsch
- Helmholtz Zentrum München - German Research Center for Environmental Health (GmbH), Institute of Biochemical Plant Pathology, Neuherberg, Germany
| | - Thorsten E E Grams
- Technical University of Munich (TUM), TUM School of Life Sciences, Land Surface-Atmosphere Interactions, Ecophysiology of Plants, Freising, Germany
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6
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He Y, Chen R, Yang Y, Liang G, Zhang H, Deng X, Xi R. Sugar Metabolism and Transcriptome Analysis Reveal Key Sugar Transporters during Camellia oleifera Fruit Development. Int J Mol Sci 2022; 23:ijms23020822. [PMID: 35055010 PMCID: PMC8775869 DOI: 10.3390/ijms23020822] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/08/2022] [Accepted: 01/10/2022] [Indexed: 12/11/2022] Open
Abstract
Camellia oleifera is a widely planted woody oil crop with economic significance because it does not occupy cultivated land. The sugar-derived acetyl-CoA is the basic building block in fatty acid synthesis and oil synthesis in C. oleifera fruit; however, sugar metabolism in this species is uncharacterized. Herein, the changes in sugar content and metabolic enzyme activity and the transcriptomic changes during C. oleifera fruit development were determined in four developmental stages (CR6: young fruit formation; CR7: expansion; CR9: oil transformation; CR10: ripening). CR7 was the key period of sugar metabolism since it had the highest amount of soluble sugar, sucrose, and glucose with a high expression of genes related to sugar transport (four sucrose transporters (SUTs) or and one SWEET-like gene, also known as a sugar, will eventually be exported transporters) and metabolism. The significant positive correlation between their expression and sucrose content suggests that they may be the key genes responsible for sucrose transport and content maintenance. Significantly differentially expressed genes enriched in the starch and sucrose metabolism pathway were observed in the CR6 versus CR10 stages according to KEGG annotation. The 26 enriched candidate genes related to sucrose metabolism provide a molecular basis for further sugar metabolism studies in C. oleifera fruit.
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Affiliation(s)
- Yu He
- Department of Forestry, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (Y.H.); (R.C.); (Y.Y.); (G.L.); (H.Z.)
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou 510642, China
| | - Ruifan Chen
- Department of Forestry, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (Y.H.); (R.C.); (Y.Y.); (G.L.); (H.Z.)
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou 510642, China
| | - Ying Yang
- Department of Forestry, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (Y.H.); (R.C.); (Y.Y.); (G.L.); (H.Z.)
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou 510642, China
| | - Guichan Liang
- Department of Forestry, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (Y.H.); (R.C.); (Y.Y.); (G.L.); (H.Z.)
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou 510642, China
| | - Heng Zhang
- Department of Forestry, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (Y.H.); (R.C.); (Y.Y.); (G.L.); (H.Z.)
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou 510642, China
| | - Xiaomei Deng
- Department of Forestry, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (Y.H.); (R.C.); (Y.Y.); (G.L.); (H.Z.)
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou 510642, China
- Correspondence: (X.D.); (R.X.)
| | - Ruchun Xi
- Department of Forestry, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China; (Y.H.); (R.C.); (Y.Y.); (G.L.); (H.Z.)
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou 510642, China
- Correspondence: (X.D.); (R.X.)
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7
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Rehschuh R, Rehschuh S, Gast A, Jakab AL, Lehmann MM, Saurer M, Gessler A, Ruehr NK. Tree allocation dynamics beyond heat and hot drought stress reveal changes in carbon storage, belowground translocation and growth. THE NEW PHYTOLOGIST 2022; 233:687-704. [PMID: 34668198 DOI: 10.1111/nph.17815] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 10/12/2021] [Indexed: 06/13/2023]
Abstract
Heatwaves combined with drought affect tree functioning with as yet undetermined legacy effects on carbon (C) and nitrogen (N) allocation. We continuously monitored shoot and root gas exchange, δ13 CO2 of respiration and stem growth in well-watered and drought-treated Pinus sylvestris (Scots pine) seedlings exposed to increasing daytime temperatures (max. 42°C) and evaporative demand. Following stress release, we used 13 CO2 canopy pulse-labeling, supplemented by soil-applied 15 N, to determine allocation to plant compartments, respiration and soil microbial biomass (SMB) over 2.5 wk. Previously heat-treated seedlings rapidly translocated 13 C along the long-distance transport path, to root respiration (Rroot ; 7.1 h) and SMB (3 d). Furthermore, 13 C accumulated in branch cellulose, suggesting secondary growth enhancement. However, in recovering drought-heat seedlings, the mean residence time of 13 C in needles increased, whereas C translocation to Rroot was delayed (13.8 h) and 13 C incorporated into starch rather than cellulose. Concurrently, we observed stress-induced low N uptake and aboveground allocation. C and N allocation during early recovery were affected by stress type and impact. Although C uptake increased quickly in both treatments, drought-heat in combination reduced the above-belowground coupling and starch accumulated in leaves at the expense of growth. Accordingly, C allocation during recovery depends on phloem translocation capacity.
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Affiliation(s)
- Romy Rehschuh
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
| | - Stephanie Rehschuh
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
| | - Andreas Gast
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
| | - Andrea-Livia Jakab
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
| | - Marco M Lehmann
- Swiss Federal Research Institute WSL, Research Unit Forest Dynamics, Birmensdorf, 8903, Switzerland
| | - Matthias Saurer
- Swiss Federal Research Institute WSL, Research Unit Forest Dynamics, Birmensdorf, 8903, Switzerland
| | - Arthur Gessler
- Swiss Federal Research Institute WSL, Research Unit Forest Dynamics, Birmensdorf, 8903, Switzerland
- Department of Environmental System Sciences, ETH Zurich, Zurich, 8092, Switzerland
| | - Nadine K Ruehr
- Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, 82467, Germany
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8
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Ouyang SN, Gessler A, Saurer M, Hagedorn F, Gao DC, Wang XY, Schaub M, Li MH, Shen WJ, Schönbeck L. Root carbon and nutrient homeostasis determines downy oak sapling survival and recovery from drought. TREE PHYSIOLOGY 2021; 41:1400-1412. [PMID: 33595075 PMCID: PMC8436808 DOI: 10.1093/treephys/tpab019] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Accepted: 02/02/2021] [Indexed: 06/12/2023]
Abstract
The role of carbon (C) and nutrient uptake, allocation, storage and especially their interactions in survival and recovery of trees under increased frequencies and intensities of drought events is not well understood. A full factorial experiment with four soil water content regimes ranging from extreme drought to well-watered conditions and two fertilization levels was carried out. We aimed to investigate whether nutrient addition mitigates drought effects on downy oak (Quercus pubescens Willd.) and whether storage pools of non-structural carbohydrates (NSC) are modified to enhance survival after 2.5 years of drought and recovery after drought relief. Physiological traits, such as photosynthesis, predawn leaf water potential as well as tissue biomass together with pools and dynamics of NSC and nutrients at the whole-tree level were investigated. Our results showed that fertilization played a minor role in saplings' physiological processes to cope with drought and drought relief, but reduced sapling mortality during extreme drought. Irrespective of nutrient supply, Q. pubescens showed increased soluble sugar concentration in all tissues with increasing drought intensity, mostly because of starch degradation. After 28 days of drought relief, tissue sugar concentrations decreased, reaching comparable values to those of well-watered plants. Only during the recovery process from extreme drought, root NSC concentration strongly declined, leading to an almost complete NSC depletion after 28 days of rewetting, simultaneously with new leaves flushing. These findings suggest that extreme drought can lead to root C exhaustion. After drought relief, the repair and regrowth of organs can even exacerbate the root C depletion. We concluded that under future climate conditions with repeated drought events, the insufficient and lagged C replenishment in roots might eventually lead to C starvation and further mortality.
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Affiliation(s)
- Sheng-Nan Ouyang
- South China Botanical Garden, Chinese Academy of Sciences,723 XingKe Road, Tianhe District, Guangzhou 510650, China
- University of Chinese Academy of Sciences, 19 Yuquan Road, Shijingshan District, Beijing 100049, China
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zurcherstrasse 111, Birmensdorf 8903, Switzerland
| | - Arthur Gessler
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zurcherstrasse 111, Birmensdorf 8903, Switzerland
- Institute of Terrestrial Ecosystems, ETH Zürich, Ramistrasse 101, Zurich 8902, Switzerland
| | - Matthias Saurer
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zurcherstrasse 111, Birmensdorf 8903, Switzerland
| | - Frank Hagedorn
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zurcherstrasse 111, Birmensdorf 8903, Switzerland
| | - De-Cai Gao
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zurcherstrasse 111, Birmensdorf 8903, Switzerland
- School of Geographical Sciences, Northeast Normal University, 5268 Renming Road, Nanguan District, Changchun 130024, China
| | - Xiao-Yu Wang
- Jiyang College, Zhejiang A&F University, 72 Puyang Road,Jiyang District, Zhuji 311800, China
| | - Marcus Schaub
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zurcherstrasse 111, Birmensdorf 8903, Switzerland
| | - Mai-He Li
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zurcherstrasse 111, Birmensdorf 8903, Switzerland
- School of Geographical Sciences, Northeast Normal University, 5268 Renming Road, Nanguan District, Changchun 130024, China
| | | | - Leonie Schönbeck
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zurcherstrasse 111, Birmensdorf 8903, Switzerland
- Plant Ecology Research Laboratory, School of Architecture, Civil and Environmental Engineering, EPFL, Route Cantonale, Lausanne 1015, Switzerland
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9
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Meeran K, Ingrisch J, Reinthaler D, Canarini A, Müller L, Pötsch EM, Richter A, Wanek W, Bahn M. Warming and elevated CO 2 intensify drought and recovery responses of grassland carbon allocation to soil respiration. GLOBAL CHANGE BIOLOGY 2021; 27:3230-3243. [PMID: 33811716 DOI: 10.1111/gcb.15628] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 03/07/2021] [Accepted: 03/15/2021] [Indexed: 05/26/2023]
Abstract
Photosynthesis and soil respiration represent the two largest fluxes of CO2 in terrestrial ecosystems and are tightly linked through belowground carbon (C) allocation. Drought has been suggested to impact the allocation of recently assimilated C to soil respiration; however, it is largely unknown how drought effects are altered by a future warmer climate under elevated atmospheric CO2 (eT_eCO2 ). In a multifactor experiment on managed C3 grassland, we studied the individual and interactive effects of drought and eT_eCO2 (drought, eT_eCO2 , drought × eT_eCO2 ) on ecosystem C dynamics. We performed two in situ 13 CO2 pulse-labeling campaigns to trace the fate of recent C during peak drought and recovery. eT_eCO2 increased soil respiration and the fraction of recently assimilated C in soil respiration. During drought, plant C uptake was reduced by c. 50% in both ambient and eT_eCO2 conditions. Soil respiration and the amount and proportion of 13 C respired from soil were reduced (by 32%, 70% and 30%, respectively), the effect being more pronounced under eT_eCO2 (50%, 84%, 70%). Under drought, the diel coupling of photosynthesis and SR persisted only in the eT_eCO2 scenario, likely caused by dynamic shifts in the use of freshly assimilated C between storage and respiration. Drought did not affect the fraction of recent C remaining in plant biomass under ambient and eT_eCO2 , but reduced the small fraction remaining in soil under eT_eCO2 . After rewetting, C uptake and the proportion of recent C in soil respiration recovered more rapidly under eT_eCO2 compared to ambient conditions. Overall, our findings suggest that in a warmer climate under elevated CO2 drought effects on the fate of recent C will be amplified and the coupling of photosynthesis and soil respiration will be sustained. To predict the future dynamics of terrestrial C cycling, such interactive effects of multiple global change factors should be considered.
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Affiliation(s)
| | | | - David Reinthaler
- Department of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Alberto Canarini
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Lena Müller
- Department of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Erich M Pötsch
- Institute of Plant Production and Cultural Landscape, Agricultural Research and Education Centre, Raumberg-Gumpenstein, Austria
| | - Andreas Richter
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Wolfgang Wanek
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Michael Bahn
- Department of Ecology, University of Innsbruck, Innsbruck, Austria
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10
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Gebauer R, Plichta R, Urban J, Volařík D, Hájíčková M. The resistance and resilience of European beech seedlings to drought stress during the period of leaf development. TREE PHYSIOLOGY 2020; 40:1147-1164. [PMID: 32470134 DOI: 10.1093/treephys/tpaa066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 05/27/2020] [Indexed: 05/26/2023]
Abstract
Spring drought is becoming a frequently occurring stress factor in temperate forests. However, the understanding of tree resistance and resilience to the spring drought remains insufficient. In this study, European beech (Fagus sylvatica L.) seedlings at the early stage of leaf development were moderately and severely drought stressed for 1 month and then subjected to a 2-week recovery period after rewatering. The study aimed to disentangle the complex relationships between leaf gas exchange, vascular anatomy, tree morphology and patterns of biomass allocation. Stomatal conductance decreased by 80 and 85% upon moderate and severe drought stress, respectively, which brought about a decline in net photosynthesis. However, drought did not affect the indices of slow chlorophyll fluorescence, indicating no permanent damage to the light part of the photosynthetic apparatus. Stem hydraulic conductivity decreased by more than 92% at both drought levels. Consequently, the cambial activity of stressed seedlings declined, which led to lower stem biomass, reduced tree ring width and a lower number of vessels in the current tree ring, these latter also with smaller dimensions. In contrast, the petiole structure was not affected, but at the cost of reduced leaf biomass. Root biomass was reduced only by severe drought. After rewatering, the recovery of gas exchange and regrowth of the current tree ring were observed, all delayed by several days and by lower magnitudes in severely stressed seedlings. The reduced stem hydraulic conductivity inhibited the recovery of gas exchange, but xylem function started to recover by regrowth and refilling of embolized vessels. Despite the damage to conductive xylem, no mortality occurred. These results suggest the low resistance but high resilience of European beech to spring drought. Nevertheless, beech resilience could be weakened if the period between drought events is short, as the recovery of severely stressed seedlings took longer than 14 days.
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Affiliation(s)
- Roman Gebauer
- Department of Forest Botany, Dendrology and Geobiocoenology, Mendel University in Brno, Zemědělská 3, 61300 Brno, Czech Republic
| | - Roman Plichta
- Department of Forest Botany, Dendrology and Geobiocoenology, Mendel University in Brno, Zemědělská 3, 61300 Brno, Czech Republic
| | - Josef Urban
- Department of Forest Botany, Dendrology and Geobiocoenology, Mendel University in Brno, Zemědělská 3, 61300 Brno, Czech Republic
- Siberian Federal University, 79 Svobodny pr., 660041 Krasnoyarsk, Russia
| | - Daniel Volařík
- Department of Forest Botany, Dendrology and Geobiocoenology, Mendel University in Brno, Zemědělská 3, 61300 Brno, Czech Republic
| | - Martina Hájíčková
- Department of Forest Botany, Dendrology and Geobiocoenology, Mendel University in Brno, Zemědělská 3, 61300 Brno, Czech Republic
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11
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Ingrisch J, Karlowsky S, Hasibeder R, Gleixner G, Bahn M. Drought and recovery effects on belowground respiration dynamics and the partitioning of recent carbon in managed and abandoned grassland. GLOBAL CHANGE BIOLOGY 2020; 26:4366-4378. [PMID: 32343042 PMCID: PMC7384171 DOI: 10.1111/gcb.15131] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 04/09/2020] [Indexed: 05/23/2023]
Abstract
The supply of soil respiration with recent photoassimilates is an important and fast pathway for respiratory loss of carbon (C). To date it is unknown how drought and land-use change interactively influence the dynamics of recent C in soil-respired CO2 . In an in situ common-garden experiment, we exposed soil-vegetation monoliths from a managed and a nearby abandoned mountain grassland to an experimental drought. Based on two 13 CO2 pulse-labelling campaigns, we traced recently assimilated C in soil respiration during drought, rewetting and early recovery. Independent of grassland management, drought reduced the absolute allocation of recent C to soil respiration. Rewetting triggered a respiration pulse, which was strongly fuelled by C assimilated during drought. In comparison to the managed grassland, the abandoned grassland partitioned more recent C to belowground respiration than to root C storage under ample water supply. Interestingly, this pattern was reversed under drought. We suggest that these different response patterns reflect strategies of the managed and the abandoned grassland to enhance their respective resilience to drought, by fostering their resistance and recovery respectively. We conclude that while severe drought can override the effects of abandonment of grassland management on the respiratory dynamics of recent C, abandonment alters strategies of belowground assimilate investment, with consequences for soil-CO2 fluxes during drought and drought-recovery.
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Affiliation(s)
| | - Stefan Karlowsky
- Max Planck Institute for BiogeochemistryJenaGermany
- Leibniz‐Institute of Vegetable and Ornamental CropsGroßbeerenGermany
| | | | | | - Michael Bahn
- Department of EcologyUniversity of InnsbruckInnsbruckAustria
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12
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Ruehr NK, Grote R, Mayr S, Arneth A. Beyond the extreme: recovery of carbon and water relations in woody plants following heat and drought stress. TREE PHYSIOLOGY 2019; 39:1285-1299. [PMID: 30924906 PMCID: PMC6703153 DOI: 10.1093/treephys/tpz032] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 01/08/2019] [Accepted: 03/13/2019] [Indexed: 05/19/2023]
Abstract
Plant responses to drought and heat stress have been extensively studied, whereas post-stress recovery, which is fundamental to understanding stress resilience, has received much less attention. Here, we present a conceptual stress-recovery framework with respect to hydraulic and metabolic functioning in woody plants. We further synthesize results from controlled experimental studies following heat or drought events and highlight underlying mechanisms that drive post-stress recovery. We find that the pace of recovery differs among physiological processes. Leaf water potential and abscisic acid concentration typically recover within few days upon rewetting, while leaf gas exchange-related variables lag behind. Under increased drought severity as indicated by a loss in xylem hydraulic conductance, the time for stomatal conductance recovery increases markedly. Following heat stress release, a similar delay in leaf gas exchange recovery has been observed, but the reasons are most likely a slow reversal of photosynthetic impairment and other temperature-related leaf damages, which typically manifest at temperatures above 40 °C. Based thereon, we suggest that recovery of gas exchange is fast following mild stress, while recovery is slow and reliant on the efficiency of repair and regrowth when stress results in functional impairment and damage to critical plant processes. We further propose that increasing stress severity, particular after critical stress levels have been reached, increases the carbon cost involved in reestablishing functionality. This concept can guide future experimental research and provides a base for modeling post-stress recovery of carbon and water relations in trees.
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Affiliation(s)
- Nadine K Ruehr
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research—Atmospheric Environmental Research (KIT/IMK-IFU), Garmisch-Partenkirchen, Germany
| | - Rüdiger Grote
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research—Atmospheric Environmental Research (KIT/IMK-IFU), Garmisch-Partenkirchen, Germany
| | - Stefan Mayr
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Almut Arneth
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research—Atmospheric Environmental Research (KIT/IMK-IFU), Garmisch-Partenkirchen, Germany
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13
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Rao S, Wu Y, Wang R. Bicarbonate stimulates non-structural carbohydrate pools of Camptotheca acuminata. PHYSIOLOGIA PLANTARUM 2019; 165:780-789. [PMID: 29900556 DOI: 10.1111/ppl.12785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 06/04/2018] [Accepted: 06/06/2018] [Indexed: 06/08/2023]
Abstract
The role of root-derived dissolved inorganic carbon (DIC) has been emphasized lately, as it can provide an alternative source of carbon for photosynthesis. The fate of newly fixed DIC and its effect on non-structural carbohydrate (NSC) pools has not been thoroughly elucidated to date. To this end, we used 13 C (NaHCO3 ) as a substrate tracer to investigate the incorporation of newly fixed bicarbonate into the plant organs and NSC compounds of Camptotheca acuminata seedlings for 24 and 72 h. NSC levels across the organs were all markedly increased within 24 h of labeling treatment and afterward only decreased in stems at 72 h. The variation range of NSC concentrations in roots was considerably smaller than in the stem and leaves. As time passed, the δ13 C in NSC compounds was significantly affected by 13 C labeling and was more positive in the roots than in the stem and leaves. Starch was more 13 C-enriched than was soluble carbohydrate, and the δ13 C of root starch was as high as -4.70‰. Bicarbonate incorporation into newly formed NSC compounds contributed up to 0.24% of the root starch within 72 h. These data provided strong evidence that bicarbonate not only acted as a C source that contributed slightly to the NSC pools but also stimulated the increase in NSC pools. The present study expands our understanding of the rapid change of NSC pools across the organs in response to bicarbonate.
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Affiliation(s)
- Sen Rao
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanyou Wu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - Rui Wang
- Food and Pharmaceutical Engineering Institute, Guiyang University, Guiyang 550005, China
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14
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Hesse BD, Goisser M, Hartmann H, Grams TEE. Repeated summer drought delays sugar export from the leaf and impairs phloem transport in mature beech. TREE PHYSIOLOGY 2019; 39:192-200. [PMID: 30388272 DOI: 10.1093/treephys/tpy122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 09/07/2018] [Accepted: 10/05/2018] [Indexed: 05/24/2023]
Abstract
Phloem sustains maintenance and growth processes through transport of sugars from source to sink organs. Under low water availability, tree functioning is impaired, i.e., growth/photosynthesis decline and phloem transport may be hindered. In a 3-year throughfall exclusion (TE) experiment on mature European beech (Fagus sylvatica L.) we conducted 13CO2 branch labeling to investigate translocation of recently fixed photoassimilates under experimental drought over 2 years (2015 and 2016). We hypothesized (H1) that mean residence time of photoassimilates in leaves (MRT) increases, whereas (H2) phloem transport velocity (Vphloem) decreases under drought. Transport of carbohydrates in the phloem was assessed via δ13C of CO2 efflux measured at two branch positions following 13CO2 labeling. Pre-dawn water potential (ΨPD) and time-integrated soil water deficit (iSWD) were used to quantify drought stress. The MRT increased by 46% from 32.1 ± 5.4 h in control (CO) to 46.9 ± 12.3 h in TE trees, supporting H1, and positively correlated (P < 0.001) with iSWD. Confirming H2, Vphloem in 2016 decreased by 47% from 20.7 ± 5.8 cm h-1 in CO to 11.0 ± 2.9 cm h-1 in TE trees and positively correlated with ΨPD (P = 0.001). We suggest that the positive correlation between MRT and iSWD is a result of the accumulation of osmolytes maintaining cell turgor in the leaves under longer drought periods. Furthermore, we propose that the positive correlation between Vphloem and ΨPD is due to a lower water uptake of phloem conduits from surrounding tissues under increasing drought leading to a higher phloem sap viscosity and lower Vphloem. The two mechanisms increasing MRT and reducing Vphloem respond differently to low water availability and impair trees' carbon translocation under drought.
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Affiliation(s)
- Benjamin D Hesse
- Technical University of Munich, Department of Ecology and Ecosystem Management - Chair for Ecophysiology of Plants, Hans-Carl-von-Carlowitz Platz 2, Freising, Germany
| | - Michael Goisser
- Technical University of Munich, Department of Ecology and Ecosystem Management - Chair for Ecophysiology of Plants, Hans-Carl-von-Carlowitz Platz 2, Freising, Germany
| | - Henrik Hartmann
- Max-Planck Institute for Biogeochemistry, Department of Biogeochemical Processes, Hans Knöll Str. 10, Jena, Germany
| | - Thorsten E E Grams
- Technical University of Munich, Department of Ecology and Ecosystem Management - Chair for Ecophysiology of Plants, Hans-Carl-von-Carlowitz Platz 2, Freising, Germany
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15
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Salmon Y, Dietrich L, Sevanto S, Hölttä T, Dannoura M, Epron D. Drought impacts on tree phloem: from cell-level responses to ecological significance. TREE PHYSIOLOGY 2019; 39:173-191. [PMID: 30726983 DOI: 10.1093/treephys/tpy153] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 12/03/2018] [Accepted: 01/25/2019] [Indexed: 06/09/2023]
Abstract
On-going climate change is increasing the risk of drought stress across large areas worldwide. Such drought events decrease ecosystem productivity and have been increasingly linked to tree mortality. Understanding how trees respond to water shortage is key to predicting the future of ecosystem functions. Phloem is at the core of the tree functions, moving resources such as non-structural carbohydrates, nutrients, and defence and information molecules across the whole plant. Phloem function and ability to transport resources is tightly controlled by the balance of carbon and water fluxes within the tree. As such, drought is expected to impact phloem function by decreasing the amount of available water and new photoassimilates. Yet, the effect of drought on the phloem has received surprisingly little attention in the last decades. Here we review existing knowledge on drought impacts on phloem transport from loading and unloading processes at cellular level to possible effects on long-distance transport and consequences to ecosystems via ecophysiological feedbacks. We also point to new research frontiers that need to be explored to improve our understanding of phloem function under drought. In particular, we show how phloem transport is affected differently by increasing drought intensity, from no response to a slowdown, and explore how severe drought might actually disrupt the phloem transport enough to threaten tree survival. Because transport of resources affects other organisms interacting with the tree, we also review the ecological consequences of phloem response to drought and especially predatory, mutualistic and competitive relations. Finally, as phloem is the main path for carbon from sources to sink, we show how drought can affect biogeochemical cycles through changes in phloem transport. Overall, existing knowledge is consistent with the hypotheses that phloem response to drought matters for understanding tree and ecosystem function. However, future research on a large range of species and ecosystems is urgently needed to gain a comprehensive understanding of the question.
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Affiliation(s)
- Yann Salmon
- Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, Gustaf Hällströmin katu 2b, University of Helsinki, Helsinki, Finland
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, Latokartanonkaari 7, University of Helsinki, Helsinki, Finland
| | - Lars Dietrich
- Department of Environmental Sciences, University of Basel, Schönbeinstrasse 6, Basel, Switzerland
| | - Sanna Sevanto
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, PO Box 1663 MA 495, Los Alamos, NM, USA
| | - Teemu Hölttä
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, Latokartanonkaari 7, University of Helsinki, Helsinki, Finland
| | - Masako Dannoura
- Kyoto University, Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto, Japan
- Kyoto University, Laboratory of Forest Utilization, Graduate School of Agriculture, Kyoto, Japan
| | - Daniel Epron
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
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16
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Dannoura M, Epron D, Desalme D, Massonnet C, Tsuji S, Plain C, Priault P, Gérant D. The impact of prolonged drought on phloem anatomy and phloem transport in young beech trees. TREE PHYSIOLOGY 2019; 39:201-210. [PMID: 29931112 DOI: 10.1093/treephys/tpy070] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 05/04/2018] [Accepted: 05/18/2018] [Indexed: 06/08/2023]
Abstract
Phloem failure has recently been recognized as one of the mechanisms causing tree mortality under drought, though direct evidence is still lacking. We combined 13C pulse-labelling of 8-year-old beech trees (Fagus sylvatica L.) growing outdoors in a nursery with an anatomical study of the phloem tissue in their stems to examine how drought alters carbon transport and phloem transport capacity. For the six trees under drought, predawn leaf water potential ranged from -0.7 to -2.4 MPa, compared with an average of -0.2 MPa in five control trees with no water stress. We also observed a longer residence time of excess 13C in the foliage and the phloem sap in trees under drought compared with controls. Compared with controls, excess 13C in trunk respiration peaked later in trees under moderate drought conditions and showed no decline even after 4 days under more severe drought conditions. We estimated higher phloem sap viscosity in trees under drought. We also observed much smaller sieve-tube radii in all drought-stressed trees, which led to lower sieve-tube conductivity and lower phloem conductance in the tree stem. We concluded that prolonged drought affected phloem transport capacity through a change in anatomy and that the slowdown of phloem transport under drought likely resulted from a reduced driving force due to lower hydrostatic pressure between the source and sink organs.
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Affiliation(s)
- Masako Dannoura
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
- Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto University, Kyoto, Japan
- Laboratory of Forest Utilization, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Daniel Epron
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Dorine Desalme
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Catherine Massonnet
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Shoko Tsuji
- Laboratory of Ecosystem Production and Dynamics, Graduate School of Global Environmental Studies, Kyoto University, Kyoto, Japan
| | - Caroline Plain
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Pierrick Priault
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
| | - Dominique Gérant
- Université de Lorraine, AgroParisTech, INRA, UMR Silva, Faculté des Sciences et Technologies, Nancy, France
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17
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Karlowsky S, Augusti A, Ingrisch J, Akanda MKU, Bahn M, Gleixner G. Drought-Induced Accumulation of Root Exudates Supports Post-drought Recovery of Microbes in Mountain Grassland. FRONTIERS IN PLANT SCIENCE 2018; 9:1593. [PMID: 30464767 PMCID: PMC6234839 DOI: 10.3389/fpls.2018.01593] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 10/15/2018] [Indexed: 05/28/2023]
Abstract
Droughts strongly affect carbon and nitrogen cycling in grasslands, with consequences for ecosystem productivity. Therefore, we investigated how experimental grassland communities interact with groups of soil microorganisms. In particular, we explored the mechanisms of the drought-induced decoupling of plant photosynthesis and microbial carbon cycling and its recovery after rewetting. Our aim was to better understand how root exudation during drought is linked to pulses of soil microbial activity and changes in plant nitrogen uptake after rewetting. We set up a mesocosm experiment on a meadow site and used shelters to simulate drought. We performed two 13C-CO2 pulse labelings, the first at peak drought and the second in the recovery phase, and traced the flow of assimilates into the carbohydrates of plants and the water extractable organic carbon and microorganisms from the soil. Total microbial tracer uptake in the main metabolism was estimated by chloroform fumigation extraction, whereas the lipid biomarkers were used to assess differences between the microbial groups. Drought led to a reduction of aboveground versus belowground plant growth and to an increase of 13C tracer contents in the carbohydrates, particularly in the roots. Newly assimilated 13C tracer unexpectedly accumulated in the water-extractable soil organic carbon, indicating that root exudation continued during the drought. In contrast, drought strongly reduced the amount of 13C tracer assimilated into the soil microorganisms. This reduction was more severe in the growth-related lipid biomarkers than in the metabolic compounds, suggesting a slowdown of microbial processes at peak drought. Shortly after rewetting, the tracer accumulation in the belowground plant carbohydrates and in the water-extractable soil organic carbon disappeared. Interestingly, this disappearance was paralleled by a quick recovery of the carbon uptake into metabolic and growth-related compounds from the rhizospheric microorganisms, which was probably related to the higher nitrogen supply to the plant shoots. We conclude that the decoupling of plant photosynthesis and soil microbial carbon cycling during drought is due to reduced carbon uptake and metabolic turnover of rhizospheric soil microorganisms. Moreover, our study suggests that the maintenance of root exudation during drought is connected to a fast reinitiation of soil microbial activity after rewetting, supporting plant recovery through increased nitrogen availability.
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Affiliation(s)
| | - Angela Augusti
- Research Institute on Terrestrial Ecosystems, Consiglio Nazionale delle Ricerche, Rome, Italy
| | | | | | - Michael Bahn
- Institute of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Gerd Gleixner
- Max Planck Institute for Biogeochemistry, Jena, Germany
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18
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Gavrichkova O, Liberati D, de Dato G, Abou Jaoudé R, Brugnoli E, de Angelis P, Guidolotti G, Pausch J, Spohn M, Tian J, Kuzyakov Y. Effects of rain shortage on carbon allocation, pools and fluxes in a Mediterranean shrub ecosystem - a 13C labelling field study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 627:1242-1252. [PMID: 30857089 DOI: 10.1016/j.scitotenv.2018.01.311] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 01/29/2018] [Accepted: 01/29/2018] [Indexed: 06/09/2023]
Abstract
Hydrological cycle is expected to become the primary cause of ecosystem's degradation in near future under changing climate. Rain manipulation experiments under field conditions provide accurate picture on the responses of biotic processes to changed water availability for plants. A field experiment, mimicking expected changes in rain patterns, was established in a Mediterranean shrub community at Porto Conte, Italy, in 2001. In November 2011 Cistus monspeliensis, one of the dominating shrub species in the Mediterranean basin, was 13C labelled on plots subjected to extended rain shortage period and on control non manipulated plots. Carbon (C) allocation was traced by 13C dynamics in shoots, shoot-respired CO2, roots, microbial biomass, K2SO4-extractable C and CO2 respired from soil. Most of the recovered 13C (60%) was respired by shoots within 2weeks in control plots. In rain shortage treatment, 13C remained incorporated in aboveground plant parts. Residence time of 13C in leaves was longer under the rain shortage because less 13C was lost by shoot respiration and because 13C was re-allocated to leaves from woody tissues. The belowground C sink was weak (3-4% of recovered 13C) and independent on rain manipulation. Extended rain shortage promoted C exudation into rhizosphere soil in expense of roots. Together with lowered photosynthesis, this "save" economy of new C metabolites reduces the growing season under rain shortage resulting in decrease of shrub cover and C losses from the system on the long-term.
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Affiliation(s)
- Olga Gavrichkova
- Institute of Agro Environmental and Forest Biology, National Research Council, Porano 05010, Monterotondo Scalo 00015 and Cinte Tesino 38050, Italy; Peoples Friendship University of Russia (RUDN University), 117198 Moscow, Russian Federation.
| | - Dario Liberati
- Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Viterbo 01100, Italy
| | - Giovanbattista de Dato
- Council for Agricultural Research and Economics (CREA) - Research Centre for Forestry and Wood, 52100 Arezzo, Italy
| | - Renée Abou Jaoudé
- Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Viterbo 01100, Italy
| | - Enrico Brugnoli
- Institute of Agro Environmental and Forest Biology, National Research Council, Porano 05010, Monterotondo Scalo 00015 and Cinte Tesino 38050, Italy
| | - Paolo de Angelis
- Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Viterbo 01100, Italy
| | - Gabriele Guidolotti
- Institute of Agro Environmental and Forest Biology, National Research Council, Porano 05010, Monterotondo Scalo 00015 and Cinte Tesino 38050, Italy
| | - Johanna Pausch
- Department of Soil Science of Temperate Ecosystems, University of Göttingen, Göttingen 37077, Germany; Department of Agricultural Soil Science, University of Göttingen, Göttingen 37077, Germany
| | - Marie Spohn
- Department of Soil Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University Bayreuth, Germany
| | - Jing Tian
- Department of Soil Science of Temperate Ecosystems, University of Göttingen, Göttingen 37077, Germany; Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences (CAS), 100101 Beijing, China; Department of Agricultural Soil Science, University of Göttingen, Göttingen 37077, Germany
| | - Yakov Kuzyakov
- Department of Soil Science of Temperate Ecosystems, University of Göttingen, Göttingen 37077, Germany; Peoples Friendship University of Russia (RUDN University), 117198 Moscow, Russian Federation; Institute of Environmental Sciences, Kazan Federal University, 420049 Kazan, Russian Federation; Department of Agricultural Soil Science, University of Göttingen, Göttingen 37077, Germany
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19
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Pflug EE, Buchmann N, Siegwolf RTW, Schaub M, Rigling A, Arend M. Resilient Leaf Physiological Response of European Beech ( Fagus sylvatica L.) to Summer Drought and Drought Release. FRONTIERS IN PLANT SCIENCE 2018; 9:187. [PMID: 29515605 PMCID: PMC5825912 DOI: 10.3389/fpls.2018.00187] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 01/31/2018] [Indexed: 05/22/2023]
Abstract
Drought is a major environmental constraint to trees, causing severe stress and thus adversely affecting their functional integrity. European beech (Fagus sylvatica L.) is a key species in mesic forests that is commonly expected to suffer in a future climate with more intense and frequent droughts. Here, we assessed the seasonal response of leaf physiological characteristics of beech saplings to drought and drought release to investigate their potential to recover from the imposed stress and overcome previous limitations. Saplings were transplanted to model ecosystems and exposed to a simulated summer drought. Pre-dawn water potentials (ψpd), stomatal conductance (gS), intercellular CO2 concentration (ci), net-photosynthesis (AN), PSII chlorophyll fluorescence (PItot), non-structural carbohydrate concentrations (NSC; soluble sugars, starch) and carbon isotope signatures were measured in leaves throughout the growing season. Pre-dawn water potentials (ψpd), gS, ci, AN, and PItot decreased as drought progressed, and the concentration of soluble sugars increased at the expense of starch. Carbon isotopes in soluble sugars (δ13CS) showed a distinct increase under drought, suggesting, together with decreased ci, stomatal limitation of AN. Drought effects on ψpd, ci, and NSC disappeared shortly after re-watering, while full recovery of gS, AN, and PItot was delayed by 1 week. The fast recovery of NSC was reflected by a rapid decay of the drought signal in δ13C values, indicating a rapid turnover of assimilates and a reactivation of carbon metabolism. After recovery, the previously drought-exposed saplings showed a stimulation of AN and a trend toward elevated starch concentrations, which counteracted the previous drought limitations. Overall, our results suggest that the internal water relations of beech saplings and the physiological activity of leaves are restored rapidly after drought release. In the case of AN, stimulation after drought may partially compensate for limitations on photosynthetic activity during drought. Our observations suggest high resilience of beech to drought, contradicting the general belief that beech is particularly sensitive to environmental stressors.
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Affiliation(s)
- Ellen E. Pflug
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
- Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Rolf T. W. Siegwolf
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, Switzerland
| | - Marcus Schaub
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
| | - Andreas Rigling
- Forest Dynamics, Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
| | - Matthias Arend
- Physiological Plant Ecology, University of Basel, Basel, Switzerland
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20
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Galiano L, Timofeeva G, Saurer M, Siegwolf R, Martínez-Vilalta J, Hommel R, Gessler A. The fate of recently fixed carbon after drought release: towards unravelling C storage regulation in Tilia platyphyllos and Pinus sylvestris. PLANT, CELL & ENVIRONMENT 2017; 40:1711-1724. [PMID: 28432768 DOI: 10.1111/pce.12972] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 04/04/2017] [Accepted: 04/07/2017] [Indexed: 06/07/2023]
Abstract
Carbon reserves are important for maintaining tree function during and after stress. Increasing tree mortality driven by drought globally has renewed the interest in how plants regulate allocation of recently fixed C to reserve formation. Three-year-old seedlings of two species (Tilia platyphyllos and Pinus sylvestris) were exposed to two intensities of experimental drought during ~10 weeks, and 13 C pulse labelling was subsequently applied with rewetting. Tracking the 13 C label across different organs and C compounds (soluble sugars, starch, myo-inositol, lipids and cellulose), together with the monitoring of gas exchange and C mass balances over time, allowed for the identification of variations in C allocation priorities and tree C balances that are associated with drought effects and subsequent drought release. The results demonstrate that soluble sugars accumulated in P. sylvestris under drought conditions independently of growth trends; thus, non-structural carbohydrates (NSC) formation cannot be simply considered a passive overflow process in this species. Once drought ceased, C allocation to storage was still prioritized at the expense of growth, which suggested the presence of 'drought memory effects', possibly to ensure future growth and survival. On the contrary, NSC and growth dynamics in T. platyphyllos were consistent with a passive (overflow) view of NSC formation.
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Affiliation(s)
- Lucía Galiano
- Swiss Federal Research Institute WSL, Birmensdorf, CH-8903, Switzerland
- Institute of Hydrology, University of Freiburg, Freiburg, D-79098, Germany
| | - Galina Timofeeva
- Swiss Federal Research Institute WSL, Birmensdorf, CH-8903, Switzerland
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute PSI, Villigen, CH-5232, Switzerland
- Forest Ecology, Department of Environmental Systems Science, Institute of Terrestrial Ecosystems, ETH Zürich, Zürich, CH-8092, Switzerland
| | - Matthias Saurer
- Swiss Federal Research Institute WSL, Birmensdorf, CH-8903, Switzerland
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute PSI, Villigen, CH-5232, Switzerland
| | - Rolf Siegwolf
- Swiss Federal Research Institute WSL, Birmensdorf, CH-8903, Switzerland
- Laboratory of Atmospheric Chemistry, Paul Scherrer Institute PSI, Villigen, CH-5232, Switzerland
| | - Jordi Martínez-Vilalta
- CREAF, Cerdanyola del Vallès, E-08193, Spain
- Autonomous University of Barcelona UAB, Cerdanyola del Vallès, E-08193, Spain
| | - Robert Hommel
- Eberswalde University of Sustainable Development, Schicklerstraße 5, 16225, Eberswalde, Germany
| | - Arthur Gessler
- Swiss Federal Research Institute WSL, Birmensdorf, CH-8903, Switzerland
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21
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Liu JF, Arend M, Yang WJ, Schaub M, Ni YY, Gessler A, Jiang ZP, Rigling A, Li MH. Effects of drought on leaf carbon source and growth of European beech are modulated by soil type. Sci Rep 2017; 7:42462. [PMID: 28195166 PMCID: PMC5307967 DOI: 10.1038/srep42462] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 01/11/2017] [Indexed: 02/01/2023] Open
Abstract
Drought potentially affects carbon balance and growth of trees, but little is known to what extent soil plays a role in the trade-off between carbon gain and growth investment. In the present study, we analyzed leaf non-structural carbohydrates (NSC) as an indicator of the balance of photosynthetic carbon gain and carbon use, as well as growth of European beech (Fagus sylvatica L.) saplings, which were grown on two different soil types (calcareous and acidic) in model ecosystems and subjected to a severe summer drought. Our results showed that drought led in general to increased total NSC concentrations and to decreased growth rate, and drought reduced shoot and stem growth of plants in acidic soil rather than in calcareous soil. This result indicated that soil type modulated the carbon trade-off between net leaf carbon gain and carbon investment to growth. In drought-stressed trees, leaf starch concentration and growth correlated negatively whereas soluble sugar:starch ratio and growth correlated positively, which may contribute to a better understanding of growth regulation under drought conditions. Our results emphasize the role of soil in determining the trade-off between the balance of carbon gain and carbon use on the leaf level and growth under stress (e.g. drought).
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Affiliation(s)
- Jian-Feng Liu
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China
- Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland
| | - Matthias Arend
- Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland
- Institute of Botany, University of Basel, Basel, Switzerland
| | - Wen-Juan Yang
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China
| | - Marcus Schaub
- Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland
| | - Yan-Yan Ni
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China
| | - Arthur Gessler
- Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland
- Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
| | - Ze-Ping Jiang
- State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China
| | - Andreas Rigling
- Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland
| | - Mai-He Li
- Swiss Federal Research Institute WSL, CH-8903 Birmensdorf, Switzerland
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
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22
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Kannenberg SA, Phillips RP. Plant responses to stress impacts: the C we do not see. TREE PHYSIOLOGY 2017; 37:151-153. [PMID: 27885174 DOI: 10.1093/treephys/tpw108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 10/20/2016] [Indexed: 06/06/2023]
Affiliation(s)
- Steven A Kannenberg
- Department of Biology, Indiana University, 1001 E. 3rd St., Bloomington, IN47405, USA
| | - Richard P Phillips
- Department of Biology, Indiana University, 1001 E. 3rd St., Bloomington, IN47405, USA
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23
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Soil microbial communities buffer physiological responses to drought stress in three hardwood species. Oecologia 2016; 183:631-641. [DOI: 10.1007/s00442-016-3783-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 11/17/2016] [Indexed: 02/07/2023]
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24
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Blessing CH, Barthel M, Gentsch L, Buchmann N. Strong Coupling of Shoot Assimilation and Soil Respiration during Drought and Recovery Periods in Beech As Indicated by Natural Abundance δ 13C Measurements. FRONTIERS IN PLANT SCIENCE 2016; 7:1710. [PMID: 27909442 PMCID: PMC5112276 DOI: 10.3389/fpls.2016.01710] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 10/31/2016] [Indexed: 05/27/2023]
Abstract
Drought down-regulates above- and belowground carbon fluxes, however, the resilience of trees to drought will also depend on the speed and magnitude of recovery of these above- and belowground fluxes after re-wetting. Carbon isotope composition of above- and belowground carbon fluxes at natural abundance provides a methodological approach to study the coupling between photosynthesis and soil respiration (SR) under conditions (such as drought) that influence photosynthetic carbon isotope discrimination. In turn, the direct supply of root respiration with recent photoassimilates will impact on the carbon isotope composition of soil-respired CO2. We independently measured shoot and soil CO2 fluxes of beech saplings (Fagus sylvatica L.) and their respective δ13C continuously with laser spectroscopy at natural abundance. We quantified the speed of recovery of drought stressed trees after re-watering and traced photosynthetic carbon isotope signal in the carbon isotope composition of soil-respired CO2. Stomatal conductance responded strongly to the moderate drought (-65%), induced by reduced soil moisture content as well as increased vapor pressure deficit. Simultaneously, carbon isotope discrimination decreased by 8‰, which in turn caused a significant increase in δ13C of recent metabolites (1.5-2.5‰) and in δ13C of SR (1-1.5‰). Generally, shoot and soil CO2 fluxes and their δ13C were in alignment during drought and subsequent stress release, clearly demonstrating a permanent dependence of root respiration on recently fixed photoassimilates, rather than on older reserves. After re-watering, the drought signal persisted longer in δ13C of the water soluble fraction that integrates multiple metabolites (soluble sugars, amino acids, organic acids) than in the neutral fraction which represents most recently assimilated sugars or in the δ13C of SR. Nevertheless, full recovery of all aboveground physiological variables was reached within 4 days - and within 7 days for SR - indicating high resilience of (young) beech against moderate drought.
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Affiliation(s)
- Carola H. Blessing
- Centre for Carbon Water and Food, University of Sydney, Brownlow HillNSW, Australia
- Institute of Agricultural Sciences, ETH ZürichZürich, Switzerland
| | - Matti Barthel
- Institute of Agricultural Sciences, ETH ZürichZürich, Switzerland
| | - Lydia Gentsch
- Chair of Bioclimatology, Georg-August University of GöttingenGöttingen, Germany
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH ZürichZürich, Switzerland
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25
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Hommel R, Siegwolf R, Zavadlav S, Arend M, Schaub M, Galiano L, Haeni M, Kayler ZE, Gessler A. Impact of interspecific competition and drought on the allocation of new assimilates in trees. PLANT BIOLOGY (STUTTGART, GERMANY) 2016; 18:785-96. [PMID: 27061772 DOI: 10.1111/plb.12461] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 04/07/2016] [Indexed: 05/21/2023]
Abstract
In trees, the interplay between reduced carbon assimilation and the inability to transport carbohydrates to the sites of demand under drought might be one of the mechanisms leading to carbon starvation. However, we largely lack knowledge on how drought effects on new assimilate allocation differ between species with different drought sensitivities and how these effects are modified by interspecific competition. We assessed the fate of (13) C labelled assimilates in above- and belowground plant organs and in root/rhizosphere respired CO2 in saplings of drought-tolerant Norway maple (Acer platanoides) and drought-sensitive European beech (Fagus sylvatica) exposed to moderate drought, either in mono- or mixed culture. While drought reduced stomatal conductance and photosynthesis rates in both species, both maintained assimilate transport belowground. Beech even allocated more new assimilate to the roots under moderate drought compared to non-limited water supply conditions, and this pattern was even more pronounced under interspecific competition. Even though maple was a superior competitor compared to beech under non-limited soil water conditions, as indicated by the changes in above- and belowground biomass of both species in the interspecific competition treatments, we can state that beech was still able to efficiently allocate new assimilate belowground under combined drought and interspecific competition. This might be seen as a strategy to maintain root osmotic potential and to prioritise root functioning. Our results thus show that beech tolerates moderate drought stress plus competition without losing its ability to supply belowground tissues. It remains to be explored in future work if this strategy is also valid during long-term drought exposure.
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Affiliation(s)
- R Hommel
- Leibniz Centre for Agricultural Landscape Research (ZALF), Institute for Landscape Biogeochemistry, Müncheberg, Germany
| | - R Siegwolf
- Laboratory of Atmospheric Chemistry, Stable Isotopes and Ecosystem Fluxes, Paul Scherrer Institute (PSI), Villigen, Switzerland
| | - S Zavadlav
- Department of Forest Physiology and Genetics, Ljubljana, Slovenia
| | - M Arend
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
| | - M Schaub
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
| | - L Galiano
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
- Institute of Hydrology, University of Freiburg, Freiburg, Germany
| | - M Haeni
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
| | - Z E Kayler
- Leibniz Centre for Agricultural Landscape Research (ZALF), Institute for Landscape Biogeochemistry, Müncheberg, Germany
| | - A Gessler
- Leibniz Centre for Agricultural Landscape Research (ZALF), Institute for Landscape Biogeochemistry, Müncheberg, Germany
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
- Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
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26
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Blessing CH, Werner RA, Siegwolf R, Buchmann N. Allocation dynamics of recently fixed carbon in beech saplings in response to increased temperatures and drought. TREE PHYSIOLOGY 2015; 35:585-98. [PMID: 25877767 DOI: 10.1093/treephys/tpv024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 03/08/2015] [Indexed: 05/05/2023]
Abstract
The response of carbon allocation to drought has often been studied in terms of short-term transport velocity of recently fixed carbon from leaves to roots and root respiration. However, its dynamic response to other environmental conditions, e.g., to changes in temperature, is less clear. Here, we investigated the effects of drought, increased temperatures and their combination on transport velocity as well as on distribution of recent photoassimilates for different compounds, such as sugars, starch, organic acids and amino acids. We used a (13)CO(2) pulse-labelling approach and studied the recovery of (13)C in different plant tissues and compounds of beech saplings (Fagus sylvatica L.) during a 9-day chase period. Neither total dry biomass nor dry weights of leaves or roots were affected by drought or increased temperatures. Generally, the fast transfer of recently fixed assimilates from leaves to roots took about 1 day, while (13)C enrichment in soil CO(2) efflux peaked only 2 days after labelling. Increased temperatures prolonged mean transfer times of recent photoassimilates from the leaves to the roots, probably caused by enhanced intermediate storage alongside basipetal transfer, clearly impacting short-term carbon allocation. This temperature effect was seen in the delayed peak in (13)C excess of root sugars, decoupling the roots from the leaves in the short term. On average, ∼40% of the (13)C label initially present in the plant was recovered in the roots (over all treatment combinations), providing strong evidence for preferred carbon allocation into the roots at the end of the growing season. Root starch was the principal compound for long-term storage of carbon, whereas leaf (transitory) starch was remobilized again after some days, exhibiting the longest mean residence times under dry and warm conditions. These observation clearly point to different functionalities of the same compound (i.e., starch) in different plant tissues and the crucial role of roots for long-term carbon storage.
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Affiliation(s)
- Carola H Blessing
- Institute of Agricultural Sciences, ETH Zurich, Universitätstrasse 2, 8048 Zurich, Switzerland
| | - Roland A Werner
- Institute of Agricultural Sciences, ETH Zurich, Universitätstrasse 2, 8048 Zurich, Switzerland
| | - Rolf Siegwolf
- Paul Scherrer Institute (PSI), Laboratory of Atmospheric Chemistry, CH-5232 Villigen PSI, Switzerland
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH Zurich, Universitätstrasse 2, 8048 Zurich, Switzerland
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