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Bourbia I, Brodribb TJ. Stomatal response to VPD is not triggered by changes in soil-leaf hydraulic conductance in Arabidopsis or Callitris. THE NEW PHYTOLOGIST 2024; 242:444-452. [PMID: 38396304 DOI: 10.1111/nph.19607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 01/29/2024] [Indexed: 02/25/2024]
Abstract
Stomatal closure under high VPDL (leaf to air vapour pressure deficit) is a primary means by which plants prevent large excursions in transpiration rate and leaf water potential (Ψleaf) that could lead to tissue damage. Yet, the drivers of this response remain controversial. Changes in Ψleaf appear to drive stomatal VPDL response, but many argue that dynamic changes in soil-to-leaf hydraulic conductance (Ks-l) make an important contribution to this response pathway, even in well-hydrated soils. Here, we examined whether the regulation of whole plant stomatal conductance (gc) in response to typical changes in daytime VPDL is influenced by dynamic changes in Ks-l. We use well-watered plants of two species with contrasting ecological and physiological features: the herbaceous Arabidopsis thaliana (ecotype Columbia-0) and the dry forest conifer Callitris rhomboidea. The dynamics of Ks-l and gc were continuously monitored by combining concurrent in situ measurements of Ψleaf using an open optical dendrometer and whole plant transpiration using a balance. Large changes in VPDL were imposed to induce stomatal closure and observe the impact on Ks-l. In both species, gc was observed to decline substantially as VPDL increased, while Ks-l remained stable. Our finding suggests that stomatal regulation of transpiration is not contingent on a decrease in Ks-l. Static Ks-l provides a much simpler explanation for transpiration control in hydrated plants and enables simplified modelling and new methods for monitoring plant water use in the field.
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Affiliation(s)
- Ibrahim Bourbia
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tas., 7001, Australia
| | - Timothy J Brodribb
- School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, Tas., 7001, Australia
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Suslov M, Daminova A, Egorov J. Real-Time Dynamics of Water Transport in the Roots of Intact Maize Plants in Response to Water Stress: The Role of Aquaporins and the Contribution of Different Water Transport Pathways. Cells 2024; 13:154. [PMID: 38247845 PMCID: PMC10814095 DOI: 10.3390/cells13020154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Revised: 12/28/2023] [Accepted: 01/09/2024] [Indexed: 01/23/2024] Open
Abstract
Using an original methodological and technical approach, we studied the real-time dynamics of radial water transfer in roots and transpiration rate in intact maize plants in response to water stress. It was shown that the response of maize plants to water stress, induced by 10% PEG 6000, was accompanied by changes in the intensity and redistribution of water transfer along different pathways of radial water transport in the roots. It was shown that during the first minutes of water stress impact, the intensity of transcellular and symplastic water transport in the roots decreased with a parallel short-term increase in the transpiration rate in leaves and, presumably, in apoplastic transport in roots. Further, after a decrease in transpiration rate, the intensity of transcellular and symplastic water transport was restored to approximately the initial values and was accompanied by parallel upregulation of some PIP aquaporin genes in roots and leaves, changes in aquaporin localization in root tissues, and changes in xylem sap pH. Under water stress conditions, cell-to-cell water transport in roots becomes dominant, and aquaporins contribute to the simultaneous regulation of water transport in roots and shoots under water stress.
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Affiliation(s)
- Maksim Suslov
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center, Russian Academy of Sciences, P.O. Box 30, Kazan 420111, Russia
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Gal A, Dalal A, Anfang M, Sharma D, Binenbaum J, Muchaki P, Kumar R, Egbaria A, Duarte KE, Kelly G, de Souza WR, Sade N. Plasma membrane aquaporins regulate root hydraulic conductivity in the model plant Setaria viridis. PLANT PHYSIOLOGY 2023; 193:2640-2660. [PMID: 37607257 DOI: 10.1093/plphys/kiad469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/26/2023] [Accepted: 08/02/2023] [Indexed: 08/24/2023]
Abstract
The high rate of productivity observed in panicoid crops is in part due to their extensive root system. Recently, green foxtail (Setaria viridis) has emerged as a genetic model system for panicoid grasses. Natural accessions of S. viridis originating from different parts of the world, with differential leaf physiological behavior, have been identified. This work focused on understanding the physiological and molecular mechanisms controlling root hydraulic conductivity and root-to-shoot gas exchange signaling in S. viridis. We identified 2 accessions, SHA and ZHA, with contrasting behavior at the leaf, root, and whole-plant levels. Our results indicated a role for root aquaporin (AQP) plasma membrane (PM) intrinsic proteins in the differential behavior of SHA and ZHA. Moreover, a different root hydraulic response to low levels of abscisic acid between SHA and ZHA was observed, which was associated with root AQPs. Using cell imaging, biochemical, and reverse genetic approaches, we identified PM intrinsic protein 1;6 (PIP1;6) as a possible PIP1 candidate that regulates radial root hydraulics and root-to-shoot signaling of gas exchange in S. viridis. In heterologous systems, PIP1;6 localized in the endoplasmic reticulum, and upon interaction with PIP2s, relocalization to the PM was observed. PIP1;6 was predominantly expressed at the root endodermis. Generation of knockout PIP1;6 plants (KO-PIP1;6) in S. viridis showed altered root hydraulic conductivity, altered gas exchange, and alteration of root transcriptional patterns. Our results indicate that PIPs are essential in regulating whole-plant water homeostasis in S. viridis. We conclude that root hydraulic conductivity and gas exchange are positively associated and are regulated by AQPs.
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Affiliation(s)
- Atara Gal
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ahan Dalal
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Moran Anfang
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Davinder Sharma
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Jenia Binenbaum
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Purity Muchaki
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Rakesh Kumar
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Aiman Egbaria
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Karoline Estefani Duarte
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Santo André 09210170, Brazil
| | - Gilor Kelly
- The Volcani Center, Institute of Plant Sciences, Agricultural Research Organization, Rishon Le-Zion 7505101, Israel
| | - Wagner Rodrigo de Souza
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Santo André 09210170, Brazil
| | - Nir Sade
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
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Ferguson JN, Jithesh T, Lawson T, Kromdijk J. Excised leaves show limited and species-specific effects on photosynthetic parameters across crop functional types. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:6662-6676. [PMID: 37565685 PMCID: PMC10662226 DOI: 10.1093/jxb/erad319] [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: 04/25/2023] [Accepted: 08/10/2023] [Indexed: 08/12/2023]
Abstract
Photosynthesis is increasingly becoming a recognized target for crop improvement. Phenotyping photosynthesis-related traits on field-grown material is a key bottleneck to progress here due to logistical barriers and short measurement days. Many studies attempt to overcome these challenges by phenotyping excised leaf material in the laboratory. To date there are no demonstrated examples of the representative nature of photosynthesis measurements performed on excised leaves relative to attached leaves in crops. Here, we tested whether standardized leaf excision on the day prior to phenotyping affected a range of common photosynthesis-related traits across crop functional types using tomato (C3 dicot), barley (C3 monocot), and maize (C4 monocot). Potentially constraining aspects of leaf physiology that could be predicted to impair photosynthesis in excised leaves, namely leaf water potential and abscisic acid accumulation, were not different between attached and excised leaves. We also observed non-significant differences in spectral reflectance and chlorophyll fluorescence traits between the treatments across the three species. However, we did observe some significant differences between traits associated with gas exchange and photosynthetic capacity across all three species. This study represents a useful reference for those who perform measurements of this nature and the differences reported should be considered in associated experimental design and statistical analyses.
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Affiliation(s)
- John N Ferguson
- Department of Plant Sciences, University of Cambridge, Cambridge, Cambridgeshire, CB2 3EA, UK
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK
| | - Tamanna Jithesh
- Department of Plant Sciences, University of Cambridge, Cambridge, Cambridgeshire, CB2 3EA, UK
| | - Tracy Lawson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK
| | - Johannes Kromdijk
- Department of Plant Sciences, University of Cambridge, Cambridge, Cambridgeshire, CB2 3EA, UK
- Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
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Abdalla M, Bitterlich M, Jansa J, Püschel D, Ahmed MA. The role of arbuscular mycorrhizal symbiosis in improving plant water status under drought. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:4808-4824. [PMID: 37409696 DOI: 10.1093/jxb/erad249] [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: 12/21/2022] [Accepted: 06/28/2023] [Indexed: 07/07/2023]
Abstract
Arbuscular mycorrhizal fungi (AMF) have been presumed to ameliorate crop tolerance to drought. Here, we review the role of AMF in maintaining water supply to plants from drying soils and the underlying biophysical mechanisms. We used a soil-plant hydraulic model to illustrate the impact of several AMF mechanisms on plant responses to edaphic drought. The AMF enhance the soil's capability to transport water and extend the effective root length, thereby attenuating the drop in matric potential at the root surface during soil drying. The synthesized evidence and the corresponding simulations demonstrate that symbiosis with AMF postpones the stress onset limit, which is defined as the disproportionality between transpiration rates and leaf water potentials, during soil drying. The symbiosis can thus help crops survive extended intervals of limited water availability. We also provide our perspective on future research needs and call for reconciling the dynamic changes in soil and root hydraulics in order to better understand the role of AMF in plant water relations in the face of climate changes.
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Affiliation(s)
- Mohanned Abdalla
- Chair of Root-Soil Interaction, School of Life Sciences, Technical University of Munich, Freising, Germany
- Chair of Soil Physics, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
- Department of Horticulture, Faculty of Agriculture, University of Khartoum, Khartoum North, Sudan
| | - Michael Bitterlich
- Humboldt-Universität zu Berlin, Thaer-Institute, Division Urban Plant Ecophysiology, Berlin, Germany
| | - Jan Jansa
- Laboratory of Fungal Biology, Institute of Microbiology, Czech Academy of Sciences, Prague, Czech Republic
| | - David Püschel
- Department of Mycorrhizal Symbioses, Institute of Botany of the Czech Academy of Sciences, Průhonice, Czech Republic
| | - Mutez A Ahmed
- Chair of Root-Soil Interaction, School of Life Sciences, Technical University of Munich, Freising, Germany
- Chair of Soil Physics, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
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Chen S, ten Tusscher KHWJ, Sasidharan R, Dekker SC, de Boer HJ. Parallels between drought and flooding: An integrated framework for plant eco-physiological responses to water stress. PLANT-ENVIRONMENT INTERACTIONS (HOBOKEN, N.J.) 2023; 4:175-187. [PMID: 37583875 PMCID: PMC10423978 DOI: 10.1002/pei3.10117] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 06/18/2023] [Indexed: 08/17/2023]
Abstract
Drought and flooding occur at opposite ends of the soil moisture spectrum yet their resulting stress responses in plants share many similarities. Drought limits root water uptake to which plants respond with stomatal closure and reduced leaf gas exchange. Flooding limits root metabolism due to soil oxygen deficiency, which also limits root water uptake and leaf gas exchange. As drought and flooding can occur consecutively in the same system and resulting plant stress responses share similar mechanisms, a single theoretical framework that integrates plant responses over a continuum of soil water conditions from drought to flooding is attractive. Based on a review of recent literature, we integrated the main plant eco-physiological mechanisms in a single theoretical framework with a focus on plant water transport, plant oxygen dynamics, and leaf gas exchange. We used theory from the soil-plant-atmosphere continuum modeling as "backbone" for our framework, and subsequently incorporated interactions between processes that regulate plant water and oxygen status, abscisic acid and ethylene levels, and the resulting acclimation strategies in response to drought, waterlogging, and complete submergence. Our theoretical framework provides a basis for the development of mathematical models to describe plant responses to the soil moisture continuum from drought to flooding.
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Affiliation(s)
- Siluo Chen
- Computational Developmental Biology, Department of BiologyUtrecht UniversityUtrechtThe Netherlands
- Centre for Complex System StudiesUtrecht UniversityUtrechtThe Netherlands
| | | | - Rashmi Sasidharan
- Plant Stress Resilience, Institute of Environmental BiologyUtrecht UniversityUtrechtThe Netherlands
| | - Stefan C. Dekker
- Environmental Sciences, Copernicus Institute of Sustainable DevelopmentUtrecht UniversityUtrechtThe Netherlands
| | - Hugo J. de Boer
- Environmental Sciences, Copernicus Institute of Sustainable DevelopmentUtrecht UniversityUtrechtThe Netherlands
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Müllers Y, Postma JA, Poorter H, van Dusschoten D. Deep-water uptake under drought improved due to locally increased root conductivity in maize, but not in faba bean. PLANT, CELL & ENVIRONMENT 2023; 46:2046-2060. [PMID: 36942406 DOI: 10.1111/pce.14587] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 03/16/2023] [Accepted: 03/19/2023] [Indexed: 06/08/2023]
Abstract
Moderate soil drying can cause a strong decrease in the soil-root system conductance. The resulting impact on root water uptake depends on the spatial distribution of the altered conductance relatively to remaining soil water resources, which is largely unknown. Here, we analyzed the vertical distribution of conductance across root systems using a novel, noninvasive sensor technology on pot-grown faba bean and maize plants. Withholding water for 4 days strongly enhanced the vertical gradient in soil water potential. Therefore, roots in upper and deeper soil layers were affected differently: In drier, upper layers, root conductance decreased by 66%-72%, causing an amplification of the drop in leaf water potential. In wetter, deeper layers, root conductance increased in maize but not in faba bean. The consequently facilitated deep-water uptake in maize contributed up to 21% of total water uptake at the end of the measurement. Analysis of root length distributions with MRI indicated that the locally increased conductance was mainly caused by an increased intrinsic conductivity and not by additional root growth. Our findings show that plants can partly compensate for a reduced root conductance in upper, drier soil layers by locally increasing root conductivity in wetter layers, thereby improving deep-water uptake.
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Affiliation(s)
- Yannik Müllers
- IBG-2, Plant Sciences, Forschungszentrum Jülich, Jülich, Germany
| | | | - Hendrik Poorter
- IBG-2, Plant Sciences, Forschungszentrum Jülich, Jülich, Germany
- Department of Natural Sciences, Macquarie University, Sydney, Australia
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Zheng C, Bochmann H, Liu Z, Kant J, Schrey SD, Wojciechowski T, Postma JA. Plant root plasticity during drought and recovery: What do we know and where to go? FRONTIERS IN PLANT SCIENCE 2023; 14:1084355. [PMID: 37008469 PMCID: PMC10061088 DOI: 10.3389/fpls.2023.1084355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 02/28/2023] [Indexed: 06/19/2023]
Abstract
AIMS Drought stress is one of the most limiting factors for agriculture and ecosystem productivity. Climate change exacerbates this threat by inducing increasingly intense and frequent drought events. Root plasticity during both drought and post-drought recovery is regarded as fundamental to understanding plant climate resilience and maximizing production. We mapped the different research areas and trends that focus on the role of roots in plant response to drought and rewatering and asked if important topics were overlooked. METHODS We performed a comprehensive bibliometric analysis based on journal articles indexed in the Web of Science platform from 1900-2022. We evaluated a) research areas and temporal evolution of keyword frequencies, b) temporal evolution and scientific mapping of the outputs over time, c) trends in the research topics analysis, d) marked journals and citation analysis, and e) competitive countries and dominant institutions to understand the temporal trends of root plasticity during both drought and recovery in the past 120 years. RESULTS Plant physiological factors, especially in the aboveground part (such as "photosynthesis", "gas-exchange", "abscisic-acid") in model plants Arabidopsis, crops such as wheat and maize, and trees were found to be the most popular study areas; they were also combined with other abiotic factors such as salinity, nitrogen, and climate change, while dynamic root growth and root system architecture responses received less attention. Co-occurrence network analysis showed that three clusters were classified for the keywords including 1) photosynthesis response; 2) physiological traits tolerance (e.g. abscisic acid); 3) root hydraulic transport. Thematically, themes evolved from classical agricultural and ecological research via molecular physiology to root plasticity during drought and recovery. The most productive (number of publications) and cited countries and institutions were situated on drylands in the USA, China, and Australia. In the past decades, scientists approached the topic mostly from a soil-plant hydraulic perspective and strongly focused on aboveground physiological regulation, whereas the actual belowground processes seemed to have been the elephant in the room. There is a strong need for better investigation into root and rhizosphere traits during drought and recovery using novel root phenotyping methods and mathematical modeling.
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Affiliation(s)
- Congcong Zheng
- Institute of Bio- and Geosciences – Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, Jülich, Germany
- Faculty of Agriculture, University of Bonn, Bonn, Germany
| | - Helena Bochmann
- Institute of Bio- and Geosciences – Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, Jülich, Germany
- Faculty of Agriculture, University of Bonn, Bonn, Germany
| | - Zhaogang Liu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
| | - Josefine Kant
- Institute of Bio- and Geosciences – Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Silvia D. Schrey
- Institute of Bio- and Geosciences – Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Tobias Wojciechowski
- Institute of Bio- and Geosciences – Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Johannes Auke Postma
- Institute of Bio- and Geosciences – Plant Sciences (IBG-2), Forschungszentrum Jülich GmbH, Jülich, Germany
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