101
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Abstract
Crassulacean acid metabolism (CAM) has evolved from a C3 ground state to increase water use efficiency of photosynthesis. During CAM evolution, selective pressures altered the abundance and expression patterns of C3 genes and their regulators to enable the trait. The circadian pattern of CO2 fixation and the stomatal opening pattern observed in CAM can be explained largely with a regulatory architecture already present in C3 plants. The metabolic CAM cycle relies on enzymes and transporters that exist in C3 plants and requires tight regulatory control to avoid futile cycles between carboxylation and decarboxylation. Ecological observations and modeling point to mesophyll conductance as a major factor during CAM evolution. The present state of knowledge enables suggestions for genes for a minimal CAM cycle for proof-of-concept engineering, assuming altered regulation of starch synthesis and degradation are not critical elements of CAM photosynthesis and sufficient malic acid export from the vacuole is possible.
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Affiliation(s)
- Katharina Schiller
- Computational Biology, Faculty of Biology, CeBiTec, Bielefeld University, 33615 Bielefeld, Germany; ,
| | - Andrea Bräutigam
- Computational Biology, Faculty of Biology, CeBiTec, Bielefeld University, 33615 Bielefeld, Germany; ,
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102
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Mukarram M, Choudhary S, Kurjak D, Petek A, Khan MMA. Drought: Sensing, signalling, effects and tolerance in higher plants. PHYSIOLOGIA PLANTARUM 2021; 172:1291-1300. [PMID: 33847385 DOI: 10.1111/ppl.13423] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 03/21/2021] [Accepted: 04/09/2021] [Indexed: 05/12/2023]
Abstract
Drought can be considered as a cocktail of multiple stressful conditions that contribute to osmotic and ionic imbalance in plants. Considering that water is vital for plant life, the very survival of the plant becomes questionable during drought conditions. Water deficit affects a wide spectrum of morpho-physiological phenomena restricting overall plant growth, development and productivity. To evade such complications and ameliorate drought-induced effects, plants have a battery of various defence mechanisms. These mechanisms can vary from stomatal adjustments to osmotic adjustments and antioxidant metabolism to ion regulations. In this review, we critically evaluate how drought is perceived and signalled through the whole plant via abscisic acid mediated pathways. Additionally, the impact of drought on photosynthesis, gas exchange variables and reactive oxygen species pathway was also reviewed, along with the reversal of these induced effects through associated morpho-physiological counter mechanisms.
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Affiliation(s)
- Mohammad Mukarram
- Advance Plant Physiology Section, Department of Botany, Aligarh Muslim University, Aligarh, India
- Department of Integrated Forest and Landscape Protection, Faculty of Forestry, Technical University in Zvolen, Zvolen, Slovakia
| | - Sadaf Choudhary
- Advance Plant Physiology Section, Department of Botany, Aligarh Muslim University, Aligarh, India
| | - Daniel Kurjak
- Department of Integrated Forest and Landscape Protection, Faculty of Forestry, Technical University in Zvolen, Zvolen, Slovakia
| | - Anja Petek
- Department of Integrated Forest and Landscape Protection, Faculty of Forestry, Technical University in Zvolen, Zvolen, Slovakia
| | - M Masroor A Khan
- Advance Plant Physiology Section, Department of Botany, Aligarh Muslim University, Aligarh, India
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103
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Flütsch S, Santelia D. Mesophyll-derived sugars are positive regulators of light-driven stomatal opening. THE NEW PHYTOLOGIST 2021; 230:1754-1760. [PMID: 33666260 DOI: 10.1111/nph.17322] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 02/08/2021] [Indexed: 06/12/2023]
Abstract
Guard cell membrane ion transport and metabolism are deeply interconnected, and their coordinated regulation is integral to stomatal opening. Whereas ion transport is exceptionally well understood, how guard cell metabolism influences stomatal movements is less well known. Organic metabolites, such as malate and sugars, fulfill several functions in guard cells during stomatal opening as allosteric activators, counter-ions, energy source and osmolytes. However, their origin and exact fate remain debated. Recent work revealed that the guard cell carbon pool regulating stomatal function and plant growth is mostly of mesophyll origin, highlighting a tight correlation between mesophyll and guard cell metabolism. This review discusses latest research into guard cell carbon metabolism and its impact on stomatal function and whole plant physiology.
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Affiliation(s)
- Sabrina Flütsch
- Institute of Integrative Biology, ETH Zürich, Universitätstrasse 16, Zürich, 8092, Switzerland
| | - Diana Santelia
- Institute of Integrative Biology, ETH Zürich, Universitätstrasse 16, Zürich, 8092, Switzerland
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104
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Mallatt J, Blatt MR, Draguhn A, Robinson DG, Taiz L. Debunking a myth: plant consciousness. PROTOPLASMA 2021; 258:459-476. [PMID: 33196907 PMCID: PMC8052213 DOI: 10.1007/s00709-020-01579-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 10/22/2020] [Indexed: 05/18/2023]
Abstract
Claims that plants have conscious experiences have increased in recent years and have received wide coverage, from the popular media to scientific journals. Such claims are misleading and have the potential to misdirect funding and governmental policy decisions. After defining basic, primary consciousness, we provide new arguments against 12 core claims made by the proponents of plant consciousness. Three important new conclusions of our study are (1) plants have not been shown to perform the proactive, anticipatory behaviors associated with consciousness, but only to sense and follow stimulus trails reactively; (2) electrophysiological signaling in plants serves immediate physiological functions rather than integrative-information processing as in nervous systems of animals, giving no indication of plant consciousness; (3) the controversial claim of classical Pavlovian learning in plants, even if correct, is irrelevant because this type of learning does not require consciousness. Finally, we present our own hypothesis, based on two logical assumptions, concerning which organisms possess consciousness. Our first assumption is that affective (emotional) consciousness is marked by an advanced capacity for operant learning about rewards and punishments. Our second assumption is that image-based conscious experience is marked by demonstrably mapped representations of the external environment within the body. Certain animals fit both of these criteria, but plants fit neither. We conclude that claims for plant consciousness are highly speculative and lack sound scientific support.
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Affiliation(s)
- Jon Mallatt
- The University of Washington WWAMI Medical Education Program at The University of Idaho, Moscow, ID 83844 USA
| | - Michael R. Blatt
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow, G12 8QQ UK
| | - Andreas Draguhn
- Institute for Physiology and Pathophysiology, Medical Faculty, University of Heidelberg, 69120 Heidelberg, Germany
| | - David G. Robinson
- Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany
| | - Lincoln Taiz
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Cruz, CA 95064 USA
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105
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Mallatt J, Blatt MR, Draguhn A, Robinson DG, Taiz L. Debunking a myth: plant consciousness. PROTOPLASMA 2021. [PMID: 33196907 DOI: 10.1007/s00709-026-01579-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Claims that plants have conscious experiences have increased in recent years and have received wide coverage, from the popular media to scientific journals. Such claims are misleading and have the potential to misdirect funding and governmental policy decisions. After defining basic, primary consciousness, we provide new arguments against 12 core claims made by the proponents of plant consciousness. Three important new conclusions of our study are (1) plants have not been shown to perform the proactive, anticipatory behaviors associated with consciousness, but only to sense and follow stimulus trails reactively; (2) electrophysiological signaling in plants serves immediate physiological functions rather than integrative-information processing as in nervous systems of animals, giving no indication of plant consciousness; (3) the controversial claim of classical Pavlovian learning in plants, even if correct, is irrelevant because this type of learning does not require consciousness. Finally, we present our own hypothesis, based on two logical assumptions, concerning which organisms possess consciousness. Our first assumption is that affective (emotional) consciousness is marked by an advanced capacity for operant learning about rewards and punishments. Our second assumption is that image-based conscious experience is marked by demonstrably mapped representations of the external environment within the body. Certain animals fit both of these criteria, but plants fit neither. We conclude that claims for plant consciousness are highly speculative and lack sound scientific support.
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Affiliation(s)
- Jon Mallatt
- The University of Washington WWAMI Medical Education Program at The University of Idaho, Moscow, ID, 83844, USA.
| | - Michael R Blatt
- Laboratory of Plant Physiology and Biophysics, Bower Building, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Andreas Draguhn
- Institute for Physiology and Pathophysiology, Medical Faculty, University of Heidelberg, 69120, Heidelberg, Germany
| | - David G Robinson
- Centre for Organismal Studies, University of Heidelberg, 69120, Heidelberg, Germany
| | - Lincoln Taiz
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Cruz, CA, 95064, USA
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106
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Movahedi M, Zoulias N, Casson SA, Sun P, Liang YK, Hetherington AM, Gray JE, Chater CCC. Stomatal responses to carbon dioxide and light require abscisic acid catabolism in Arabidopsis. Interface Focus 2021; 11:20200036. [PMID: 33633834 DOI: 10.1098/rsfs.2020.0036] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2020] [Indexed: 11/12/2022] Open
Abstract
In plants, stomata control water loss and CO2 uptake. The aperture and density of stomatal pores, and hence the exchange of gases between the plant and the atmosphere, are controlled by internal factors such as the plant hormone abscisic acid (ABA) and external signals including light and CO2. In this study, we examine the importance of ABA catabolism in the stomatal responses to CO2 and light. By using the ABA 8'-hydroxylase-deficient Arabidopsis thaliana double mutant cyp707a1 cyp707a3, which is unable to break down and instead accumulates high levels of ABA, we reveal the importance of the control of ABA concentration in mediating stomatal responses to CO2 and light. Intriguingly, our experiments suggest that endogenously produced ABA is unable to close stomata in the absence of CO2. Furthermore, we show that when plants are grown in short day conditions ABA breakdown is required for the modulation of both elevated [CO2]-induced stomatal closure and elevated [CO2]-induced reductions in leaf stomatal density. ABA catabolism is also required for the stomatal density response to light intensity, and for the full range of light-induced stomatal opening, suggesting that ABA catabolism is critical for the integration of stomatal responses to a range of environmental stimuli.
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Affiliation(s)
- Mahsa Movahedi
- Clinical Biomanufacturing Facility, Old Road, Headington, Oxford OX3 7JT, UK
| | - Nicholas Zoulias
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Stuart A Casson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Peng Sun
- State Key Laboratory of Hybrid Rice, Department of Plant Science, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Yun-Kuan Liang
- State Key Laboratory of Hybrid Rice, Department of Plant Science, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
| | - Alistair M Hetherington
- School of Biological Sciences, Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Julie E Gray
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Caspar C C Chater
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.,Department of Natural Capital and Plant Health, Royal Botanic Gardens, Kew, Richmond TW9 3AE, UK
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107
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Zhao C, Chavan S, He X, Zhou M, Cazzonelli CI, Chen ZH, Tissue DT, Ghannoum O. Smart glass impacts stomatal sensitivity of greenhouse Capsicum through altered light. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:3235-3248. [PMID: 33484266 DOI: 10.1093/jxb/erab028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 01/19/2021] [Indexed: 06/12/2023]
Abstract
Optical films that alter light transmittance may reduce energy consumption in high-tech greenhouses, but their impact on crop physiology remains unclear. We compared the stomatal responses of Capsicum plants grown hydroponically under control glass (70% diffuse light) or the smart glass (SG) film ULR-80, which blocked >50% of short-wave radiation and ~9% of photosynthetically active radiation (PAR). SG had no significant effects on steady-state (gs) or maximal (gmax) stomatal conductance. In contrast, SG reduced stomatal pore size and sensitivity to exogenous abscisic acid (ABA), thereby increasing rates of leaf water loss, guard cell K+ and Cl- efflux, and Ca2+ influx. SG induced faster stomatal closing and opening rates on transition between low (100 µmol m-2 s-1) and high PAR (1500 µmol m-2 s-1), which compromised water use efficiency relative to control plants. The fraction of blue light (0% or 10%) did not affect gs in either treatment. Increased expression of stomatal closure and photoreceptor genes in epidermal peels of SG plants is consistent with fast stomatal responses to light changes. In conclusion, stomatal responses of Capsicum to SG were more affected by changes in light intensity than spectral quality, and re-engineering of the SG should maximize PAR transmission, and hence CO2 assimilation.
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Affiliation(s)
- Chenchen Zhao
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
- School of Science, Western Sydney University, Penrith, NSW 2753, Australia
- Tasmanian Institute of Agriculture, University of Tasmania, Prospect, TAS, 7250, Australia
| | - Sachin Chavan
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
- National Vegetable Protected Cropping Centre, Western Sydney University, Hawkesbury Campus, Richmond, NSW 2753, Australia
| | - Xin He
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
- National Vegetable Protected Cropping Centre, Western Sydney University, Hawkesbury Campus, Richmond, NSW 2753, Australia
| | - Meixue Zhou
- Tasmanian Institute of Agriculture, University of Tasmania, Prospect, TAS, 7250, Australia
| | - Christopher I Cazzonelli
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
- National Vegetable Protected Cropping Centre, Western Sydney University, Hawkesbury Campus, Richmond, NSW 2753, Australia
| | - Zhong-Hua Chen
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
- School of Science, Western Sydney University, Penrith, NSW 2753, Australia
- National Vegetable Protected Cropping Centre, Western Sydney University, Hawkesbury Campus, Richmond, NSW 2753, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
- National Vegetable Protected Cropping Centre, Western Sydney University, Hawkesbury Campus, Richmond, NSW 2753, Australia
| | - Oula Ghannoum
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
- National Vegetable Protected Cropping Centre, Western Sydney University, Hawkesbury Campus, Richmond, NSW 2753, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Australia
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108
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Moore CE, Meacham-Hensold K, Lemonnier P, Slattery RA, Benjamin C, Bernacchi CJ, Lawson T, Cavanagh AP. The effect of increasing temperature on crop photosynthesis: from enzymes to ecosystems. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:2822-2844. [PMID: 33619527 PMCID: PMC8023210 DOI: 10.1093/jxb/erab090] [Citation(s) in RCA: 101] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 02/19/2021] [Indexed: 05/03/2023]
Abstract
As global land surface temperature continues to rise and heatwave events increase in frequency, duration, and/or intensity, our key food and fuel cropping systems will likely face increased heat-related stress. A large volume of literature exists on exploring measured and modelled impacts of rising temperature on crop photosynthesis, from enzymatic responses within the leaf up to larger ecosystem-scale responses that reflect seasonal and interannual crop responses to heat. This review discusses (i) how crop photosynthesis changes with temperature at the enzymatic scale within the leaf; (ii) how stomata and plant transport systems are affected by temperature; (iii) what features make a plant susceptible or tolerant to elevated temperature and heat stress; and (iv) how these temperature and heat effects compound at the ecosystem scale to affect crop yields. Throughout the review, we identify current advancements and future research trajectories that are needed to make our cropping systems more resilient to rising temperature and heat stress, which are both projected to occur due to current global fossil fuel emissions.
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Affiliation(s)
- Caitlin E Moore
- School of Agriculture and Environment, The University of Western Australia, Crawley, Australia
- Institute for Sustainability, Energy & Environment, University of Illinois at Urbana-Champaign, Urbana, USA
- Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, USA
- Correspondence: or
| | - Katherine Meacham-Hensold
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, USA
| | | | - Rebecca A Slattery
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, USA
| | - Claire Benjamin
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, USA
| | - Carl J Bernacchi
- Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, USA
- Global Change and Photosynthesis Research Unit, United States Department of Agriculture–Agricultural Research Service, Urbana, USA
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, USA
| | - Tracy Lawson
- School of Life Sciences, University of Essex, Colchester, UK
| | - Amanda P Cavanagh
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, USA
- School of Life Sciences, University of Essex, Colchester, UK
- Correspondence: or
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109
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Ozone Response of Leaf Physiological and Stomatal Characteristics in Brassica juncea L. at Supraoptimal Temperatures. LAND 2021. [DOI: 10.3390/land10040357] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Plants are affected by the features of their surrounding environment, such as climate change and air pollution caused by anthropogenic activities. In particular, agricultural production is highly sensitive to environmental characteristics. Since no environmental factor is independent, the interactive effects of these factors on plants are essential for agricultural production. In this context, the interactive effects of ozone (O3) and supraoptimal temperatures remain unclear. Here, we investigated the physiological and stomatal characteristics of leaf mustard (Brassica juncea L.) in the presence of charcoal-filtered (target concentration, 10 ppb) and elevated (target concentration, 120 ppb) O3 concentrations and/or optimal (22/20 °C day/night) and supraoptimal temperatures (27/25 °C). Regarding physiological characteristics, the maximum rate of electron transport and triose phosphate use significantly decreased in the presence of elevated O3 at a supraoptimal temperature (OT conditions) compared with those in the presence of elevated O3 at an optimal temperature (O conditions). Total chlorophyll content was also significantly affected by supraoptimal temperature and elevated O3. The chlorophyll a/b ratio significantly reduced under OT conditions compared to C condition at 7 days after the beginning of exposure (DAE). Regarding stomatal characteristics, there was no significant difference in stomatal pore area between O and OT conditions, but stomatal density under OT conditions was significantly increased compared with that under O conditions. At 14 DAE, the levels of superoxide (O2-), which is a reactive oxygen species, were significantly increased under OT conditions compared with those under O conditions. Furthermore, leaf weight was significantly reduced under OT conditions compared with that under O conditions. Collectively, these results indicate that temperature is a key driver of the O3 response of B. juncea via changes in leaf physiological and stomatal characteristics.
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110
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Pantaleno R, Scuffi D, García-Mata C. Hydrogen sulphide as a guard cell network regulator. THE NEW PHYTOLOGIST 2021; 230:451-456. [PMID: 33251582 DOI: 10.1111/nph.17113] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/08/2020] [Indexed: 06/12/2023]
Abstract
Hydrogen sulphide (H2 S) is an endogenously produced gasotransmitter that has rapidly emerged as an active signalling component of several plant processes, stomatal movement regulation among them. The guard cells (GCs), pairs of cells that neighbour the stomatal pores, transduce endogenous and environmental signals, through signalling network, to control stomatal pore size. In this complex network, which has become a model system for plant signalling, few highly connected components form a core that links most of the pathways. The evidence summarized in this insight, on the interplay between H2 S and different key components of the GC networks, points towards H2 S as a regulator of the GC core signalling pathway.
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Affiliation(s)
- Rosario Pantaleno
- Instituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Mar del Plata, 7600, Argentina
| | - Denise Scuffi
- Instituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Mar del Plata, 7600, Argentina
| | - Carlos García-Mata
- Instituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Mar del Plata, 7600, Argentina
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111
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Wilson MJ, Fradera‐Soler M, Summers R, Sturrock CJ, Fleming AJ. Ploidy influences wheat mesophyll cell geometry, packing and leaf function. PLANT DIRECT 2021; 5:e00314. [PMID: 33855257 PMCID: PMC8026107 DOI: 10.1002/pld3.314] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/08/2020] [Accepted: 02/21/2021] [Indexed: 05/06/2023]
Abstract
Leaf function is influenced by leaf structure, which is itself related not only to the spatial arrangement of constituent mesophyll cells, but also their size and shape. In this study, we used confocal microscopy to image leaves of Triticum genotypes varying in ploidy level to extract 3D information on individual mesophyll cell size and geometry. Combined with X-ray Computed Tomography and gas exchange analysis, the effect of changes in wheat mesophyll cell geometry upon leaf structure and function were investigated. Mesophyll cell size and shape were found to have changed during the course of wheat evolution. An unexpected linear relationship between mesophyll cell surface area and volume was discovered, suggesting anisotropic scaling of mesophyll cell geometry with increasing ploidy. Altered mesophyll cell size and shape were demonstrated to be associated with changes in mesophyll tissue architecture. Under experimental growth conditions, CO2 assimilation did not vary with ploidy, but stomatal conductance was lower in hexaploid plants, conferring a greater instantaneous water-use efficiency. We propose that as wheat mesophyll cells have become larger with increased ploidy, this has been accompanied by changes in cell geometry and packing which limit water loss while maintaining carbon assimilation.
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Affiliation(s)
- Matthew J. Wilson
- Department of Animal and Plant SciencesUniversity of SheffieldSheffieldUK
| | - Marc Fradera‐Soler
- Department of Plant and Environmental SciencesUniversity of CopenhagenCopenhagenDenmark
- Hounsfield FacilityDivision of Agriculture and Environmental SciencesSchool of BiosciencesUniversity of NottinghamSutton BoningtonUK
| | | | - Craig J. Sturrock
- Hounsfield FacilityDivision of Agriculture and Environmental SciencesSchool of BiosciencesUniversity of NottinghamSutton BoningtonUK
| | - Andrew J. Fleming
- Department of Animal and Plant SciencesUniversity of SheffieldSheffieldUK
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112
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Pridgeon AJ, Hetherington AM. ABA signalling and metabolism are not essential for dark-induced stomatal closure but affect response speed. Sci Rep 2021; 11:5751. [PMID: 33707501 PMCID: PMC7952387 DOI: 10.1038/s41598-021-84911-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 02/17/2021] [Indexed: 11/16/2022] Open
Abstract
Stomata are microscopic pores that open and close, acting to balance CO2 uptake with water loss. Stomata close in response to various signals including the drought hormone abscisic acid (ABA), microbe-associated-molecular-patterns, high CO2 levels, and darkness. The signalling pathways underlying ABA-induced stomatal closure are well known, however, the mechanism for dark-induced stomatal closure is less clear. ABA signalling has been suggested to play a role in dark-induced stomatal closure, but it is unclear how this occurs. Here we investigate the role of ABA in promoting dark-induced stomatal closure. Tracking stomatal movements on the surface of leaf discs we find, although steady state stomatal apertures are affected by mutations in ABA signalling and metabolism genes, all mutants investigated close in response to darkness. However, we observed a delayed response to darkness for certain ABA signalling and metabolism mutants. Investigating this further in the quadruple ABA receptor mutant (pyr1pyl1pyl2pyl4), compared with wild-type, we found reduced stomatal conductance kinetics. Although our results suggest a non-essential role for ABA in dark-induced stomatal closure, we show that ABA modulates the speed of the dark-induced closure response. These results highlight the role of ABA signalling and metabolic pathways as potential targets for enhancing stomatal movement kinetics.
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Affiliation(s)
- Ashley J Pridgeon
- School of Biological Sciences, Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
| | - Alistair M Hetherington
- School of Biological Sciences, Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK.
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113
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Franzisky BL, Geilfus CM, Romo-Pérez ML, Fehrle I, Erban A, Kopka J, Zörb C. Acclimatisation of guard cell metabolism to long-term salinity. PLANT, CELL & ENVIRONMENT 2021; 44:870-884. [PMID: 33251628 DOI: 10.1111/pce.13964] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 11/19/2020] [Accepted: 11/26/2020] [Indexed: 06/12/2023]
Abstract
Stomatal movements are enabled by changes in guard cell turgor facilitated via transient accumulation of inorganic and organic ions imported from the apoplast or biosynthesized within guard cells. Under salinity, excess salt ions accumulate within plant tissues resulting in osmotic and ionic stress. To elucidate whether (a) Na+ and Cl- concentrations increase in guard cells in response to long-term NaCl exposure and how (b) guard cell metabolism acclimates to the anticipated stress, we profiled the ions and primary metabolites of leaves, the apoplast and isolated guard cells at darkness and during light, that is, closed and fully opened stomata. In contrast to leaves, the primary metabolism of guard cell preparations remained predominantly unaffected by increased salt ion concentrations. Orchestrated reductions of stomatal aperture and guard cell osmolyte synthesis were found, but unlike in leaves, no increases of stress responsive metabolites or compatible solutes occurred. Diverging regulation of guard cell metabolism might be a prerequisite to facilitate the constant adjustment of turgor that affects aperture. Moreover, the photoperiod-dependent sucrose accumulation in the apoplast and guard cells changed to a permanently replete condition under NaCl, indicating that stress-related photosynthate accumulation in leaves contributes to the permanent closing response of stomata under stress.
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Affiliation(s)
| | - Christoph-Martin Geilfus
- Division of Controlled Environment Horticulture, Faculty of Life Sciences, Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Humboldt-University of Berlin, Berlin, Germany
| | | | - Ines Fehrle
- Max-Planck-Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Alexander Erban
- Max-Planck-Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Joachim Kopka
- Max-Planck-Institute of Molecular Plant Physiology, Potsdam-Golm, Germany
| | - Christian Zörb
- Institute of Crop Science, University of Hohenheim, Stuttgart, Germany
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Vandegeer RK, Zhao C, Cibils-Stewart X, Wuhrer R, Hall CR, Hartley SE, Tissue DT, Johnson SN. Silicon deposition on guard cells increases stomatal sensitivity as mediated by K + efflux and consequently reduces stomatal conductance. PHYSIOLOGIA PLANTARUM 2021; 171:358-370. [PMID: 32880970 DOI: 10.1111/ppl.13202] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/27/2020] [Accepted: 09/01/2020] [Indexed: 06/11/2023]
Abstract
Silicon (Si) has been widely reported to improve plant resistance to water stress via various mechanisms including cuticular Si deposition to reduce leaf transpiration. However, there is limited understanding of the effects of Si on stomatal physiology, including the underlying mechanisms and implications for resistance to water stress. We grew tall fescue (Festuca arundinacea Schreb. cv. Fortuna) hydroponically, with or without Si, and treated half of the plants with 20% polyethylene glycol to impose physiological drought (osmotic stress). Scanning electron microscopy in conjunction with X-ray mapping found that Si was deposited on stomatal guard cells and as a sub-cuticular layer in Si-treated plants. Plants grown in Si had a 28% reduction in stomatal conductance and a 23% reduction in cuticular conductance. When abscisic acid was applied exogenously to epidermal leaf peels to promote stomatal closure, Si plants had 19% lower stomatal aperture compared to control plants (i.e. increased stomatal sensitivity) and an increased efflux of guard cell K+ ions. However, the changes in stomatal physiology with Si were not substantial enough to improve water stress resistance, as shown by a lack of significant effect of Si on water potential, growth, photosynthesis and water-use efficiency. Our findings suggest a novel underlying mechanism for reduced stomatal conductance with Si application; specifically, that Si deposition on stomatal guard cells promotes greater stomatal sensitivity as mediated by guard cell K+ efflux.
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Affiliation(s)
- Rebecca K Vandegeer
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales, 2751, Australia
| | - Chenchen Zhao
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales, 2751, Australia
| | - Ximena Cibils-Stewart
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales, 2751, Australia
- Instituto Nacional de Investigación Agropecuaria (INIA), La Estanzuela Research Station, Ruta 50, Km. 11, Colonia, Uruguay
| | - Richard Wuhrer
- Advanced Materials Characterisation Facility (AMCF), Western Sydney University, Locked Bag 1797, Penrith, New South Wales, 2751, Australia
| | - Casey R Hall
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales, 2751, Australia
| | - Susan E Hartley
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales, 2751, Australia
| | - Scott N Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales, 2751, Australia
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115
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Waqas M, Yaning C, Iqbal H, Shareef M, Rehman HU, Bilal HM. Synergistic consequences of salinity and potassium deficiency in quinoa: Linking with stomatal patterning, ionic relations and oxidative metabolism. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 159:17-27. [PMID: 33310530 DOI: 10.1016/j.plaphy.2020.11.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/05/2020] [Indexed: 06/12/2023]
Abstract
Quinoa emerged as an ideal food security crop due to its exceptional nutritive profile and stress enduring potential and also deemed as model plant to study the salt-tolerance mechanisms. However to fill the research gaps of this imperative crop, the present work aimed to study the effect of potassium (K) deficiency either separately or in combination with salinity. First, we investigated the stomatal and physiological based variations in quinoa growth under salinity and K, then series of analytical tools were used with model approach to interpret the stomatal aperture (SA) and photosynthesis (Pn) changes. Results revealed that quinoa efficiently deployed antioxidants to scavenge the excessive reactive oxygen species (ROS), had high uptake and retention of K+, Ca2+, Mg2+ with Cl⁻ as charge balancing ion, increased stomata density (SD) and declined the SA to maintain the Pn which resulted the improved growth under salinity. Whereas, K-deficiency caused the stunted growth more severally under salinity due to disruption in ionic homeostasis, excessive ROS production elicited the oxidative damages, SD and SA reduced and ultimately declined in Pn. Our best fitted regression model explored that dependent variables like Pn and SA changed according to theirs signified explanatory variables with quantification per unit based as stomatal conductance (Gs, 51), SD (0.05), ROS (-0.79) and K+ (0.08), Cl⁻ (0.34) and Na+ (- 0.52) respectively. Overall, moderate salinity promoted the quinoa growth, while K-deficiency particularly with salinity reduced the quinoa performance by affecting stomatal and non-stomatal factors.
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Affiliation(s)
- Muhammad Waqas
- State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China; Xinjiang Institute of Ecology and Geography, University of Chinese Academy of Sciences, Beijing, China; Department of Environmental Sciences, University of Okara, Punjab, Pakistan.
| | - Chen Yaning
- State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China.
| | - Hassan Iqbal
- State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China; Xinjiang Institute of Ecology and Geography, University of Chinese Academy of Sciences, Beijing, China
| | - Muhammad Shareef
- Cele National Station for Desert and Grassland Observation and Research, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China; Department of Botany, Division of Science and Technology, University of Education Lahore, Pakistan; Department of Botany, Hameeda Rasheed Institute of Science and Technology, Multan, Pakistan
| | - Hafeez Ur Rehman
- Department of Agronomy, University of Agriculture, Faisalabad, Pakistan
| | - Hafiz Muhammad Bilal
- Department of Environmental Sciences, University of Okara, Punjab, Pakistan; PARC-Arid Zone Research Institute, Umerkot, Sindh, Pakistan
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116
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Pignon CP, Leakey ADB, Long SP, Kromdijk J. Drivers of Natural Variation in Water-Use Efficiency Under Fluctuating Light Are Promising Targets for Improvement in Sorghum. FRONTIERS IN PLANT SCIENCE 2021; 12:627432. [PMID: 33597965 PMCID: PMC7882533 DOI: 10.3389/fpls.2021.627432] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 01/05/2021] [Indexed: 05/20/2023]
Abstract
Improving leaf intrinsic water-use efficiency (iWUE), the ratio of photosynthetic CO2 assimilation to stomatal conductance, could decrease crop freshwater consumption. iWUE has primarily been studied under steady-state light, but light in crop stands rapidly fluctuates. Leaf responses to these fluctuations substantially affect overall plant performance. Notably, photosynthesis responds faster than stomata to decreases in light intensity: this desynchronization results in substantial loss of iWUE. Traits that could improve iWUE under fluctuating light, such as faster stomatal movement to better synchronize stomata with photosynthesis, show significant natural diversity in C3 species. However, C4 crops have been less closely investigated. Additionally, while modification of photosynthetic or stomatal traits independent of one another will theoretically have a proportionate effect on iWUE, in reality these traits are inter-dependent. It is unclear how interactions between photosynthesis and stomata affect natural diversity in iWUE, and whether some traits are more tractable drivers to improve iWUE. Here, measurements of photosynthesis, stomatal conductance and iWUE under steady-state and fluctuating light, along with stomatal patterning, were obtained in 18 field-grown accessions of the C4 crop sorghum. These traits showed significant natural diversity but were highly correlated, with important implications for improvement of iWUE. Some features, such as gradual responses of photosynthesis to decreases in light, appeared promising for improvement of iWUE. Other traits showed tradeoffs that negated benefits to iWUE, e.g., accessions with faster stomatal responses to decreases in light, expected to benefit iWUE, also displayed more abrupt losses in photosynthesis, resulting in overall lower iWUE. Genetic engineering might be needed to break these natural tradeoffs and achieve optimal trait combinations, e.g., leaves with fewer, smaller stomata, more sensitive to changes in photosynthesis. Traits describing iWUE at steady-state, and the change in iWUE following decreases in light, were important contributors to overall iWUE under fluctuating light.
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Affiliation(s)
- Charles P. Pignon
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Andrew D. B. Leakey
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- *Correspondence: Andrew D. B. Leakey,
| | - Stephen P. Long
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom
| | - Johannes Kromdijk
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
- Department of Plant Sciences, University of Cambridge, Cambridge, United Kingdom
- Johannes Kromdijk, ;
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117
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Westbrook AS, McAdam SAM. Stomatal density and mechanics are critical for high productivity: insights from amphibious ferns. THE NEW PHYTOLOGIST 2021; 229:877-889. [PMID: 32761918 DOI: 10.1111/nph.16850] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 07/28/2020] [Indexed: 06/11/2023]
Abstract
Angiosperm dominance in terrestrial landscapes is partially attributable to high photosynthetic capacities. Angiosperms benefit from diverse anatomical and physiological adaptations, making it difficult to determine which factors may have been prerequisites for the evolution of enhanced photosynthetic rates in this group. We employed a novel approach to this problem: comparisons between angiosperms and Marsileaceae, a family of semi-aquatic ferns that are among the only land plants to match angiosperm photosynthetic rates. We found that Marsileaceae have very high stomatal densities and, like angiosperms but unlike all other ferns previously studied, exhibit wrong-way stomatal responses to excision. These results suggest that stomatal density and a little-studied angiosperm trait, the capacity for lateral displacement of guard cells into neighboring epidermal cells, are crucial for facilitating high rates of gas exchange. Our analysis also associates these adaptations in Marsileaceae with an increased risk of excessive water loss during drought. Our findings indicate that evolution in stomatal physiology was a prerequisite for high photosynthetic capacities in vascular plants and a key driver of the abrupt Cretaceous rise of the angiosperms.
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Affiliation(s)
- Anna S Westbrook
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA
| | - Scott A M McAdam
- Department of Botany and Plant Pathology, Purdue Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA
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118
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Santos MG, Davey PA, Hofmann TA, Borland A, Hartwell J, Lawson T. Stomatal Responses to Light, CO 2, and Mesophyll Tissue in Vicia faba and Kalanchoë fedtschenkoi. FRONTIERS IN PLANT SCIENCE 2021; 12:740534. [PMID: 34777422 PMCID: PMC8579043 DOI: 10.3389/fpls.2021.740534] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 09/22/2021] [Indexed: 05/14/2023]
Abstract
The responses of stomatal aperture to light intensity and CO2 concentration were studied in both Vicia faba (C3) and Kalanchoë fedtschenkoi (Crassulacean acid metabolism; CAM), in material sampled from both light and dark periods. Direct comparison was made between intact leaf segments, epidermises grafted onto exposed mesophyll, and isolated epidermal peels, including transplantations between species and between diel periods. We reported the stomatal opening in response to darkness in isolated CAM peels from the light period, but not from the dark. Furthermore, we showed that C3 mesophyll has stimulated CAM stomata in transplanted peels to behave as C3 in response to light and CO2. By using peels and mesophyll from plants sampled in the dark and the light period, we provided clear evidence that CAM stomata behaved differently from C3. This might be linked to stored metabolites/ions and signalling pathway components within the guard cells, and/or a mesophyll-derived signal. Overall, our results provided evidence for both the involvement of guard cell metabolism and mesophyll signals in stomatal responses in both C3 and CAM species.
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Affiliation(s)
- Mauro G. Santos
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, United Kingdom
| | - Phillip A. Davey
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, United Kingdom
| | | | - Anne Borland
- School of Natural and Environmental Sciences, Devonshire Building, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - James Hartwell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Tracy Lawson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, United Kingdom
- *Correspondence: Tracy Lawson
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119
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Stomatal and Leaf Morphology Response of European Beech (Fagus sylvatica L.) Provenances Transferred to Contrasting Climatic Conditions. FORESTS 2020. [DOI: 10.3390/f11121359] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Climate change-induced elevated temperatures and drought are considered to be serious threats to forest ecosystems worldwide, negatively affecting tree growth and viability. We studied nine European beech (Fagus sylvatica L.) provenances located in two provenance trial plots with contrasting climates in Central Europe. Stomata play a vital role in the water balance of plants by regulating gaseous exchanges between plants and the atmosphere. Therefore, to explain the possible adaptation and acclimation of provenances to climate conditions, stomatal (stomatal density, the length of guard cells, and the potential conductance index) and leaf morphological traits (leaf size, leaf dry weight and specific leaf area) were assessed. The phenotypic plasticity index was calculated from the variability of provenances’ stomatal and leaf traits between the provenance plots. We assessed the impact of various climatic characteristics and derived indices (e.g., ecodistance) on intraspecific differences in stomatal and leaf traits. Provenances transferred to drier and warmer conditions acclimated through a decrease in stomatal density, the length of guard cells, potential conductance index, leaf size and leaf dry weight. The reduction in stomatal density and the potential conductance index was proportional to the degree of aridity difference between the climate of origin and conditions of the new site. Moreover, we found that the climate heterogeneity and latitude of the original provenance sites influence the phenotypic plasticity of provenances. Provenances from lower latitudes and less heterogeneous climates showed higher values of phenotypic plasticity. Furthermore, we observed a positive correlation between phenotypic plasticity and mortality in the arid plot but not in the more humid plot. Based on these impacts of the climate on stomatal and leaf traits of transferred provenances, we can improve the predictions of provenance reactions for future scenarios of global climate change.
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