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Carter R, Woolfenden H, Baillie A, Amsbury S, Carroll S, Healicon E, Sovatzoglou S, Braybrook S, Gray JE, Hobbs J, Morris RJ, Fleming AJ. Stomatal Opening Involves Polar, Not Radial, Stiffening Of Guard Cells. Curr Biol 2017; 27:2974-2983.e2. [PMID: 28943087 PMCID: PMC5640513 DOI: 10.1016/j.cub.2017.08.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/14/2017] [Accepted: 08/02/2017] [Indexed: 11/23/2022]
Abstract
It has long been accepted that differential radial thickening of guard cells plays an important role in the turgor-driven shape changes required for stomatal pore opening to occur [1, 2, 3, 4]. This textbook description derives from an original interpretation of structure rather than measurement of mechanical properties. Here we show, using atomic force microscopy, that although mature guard cells display a radial gradient of stiffness, this is not present in immature guard cells, yet young stomata show a normal opening response. Finite element modeling supports the experimental observation that radial stiffening plays a very limited role in stomatal opening. In addition, our analysis reveals an unexpected stiffening of the polar regions of the stomata complexes, both in Arabidopsis and other plants, suggesting a widespread occurrence. Combined experimental data (analysis of guard cell wall epitopes and treatment of tissue with cell wall digesting enzymes, coupled with bioassay of guard cell function) plus modeling lead us to propose that polar stiffening reflects a mechanical, pectin-based pinning down of the guard cell ends, which restricts increase of stomatal complex length during opening. This is predicted to lead to an improved response sensitivity of stomatal aperture movement with respect to change of turgor pressure. Our results provide new insight into the mechanics of stomatal function, both negating an established view of the importance of radial thickening and providing evidence for a significant role for polar stiffening. Improved stomatal performance via altered cell-wall-mediated mechanics is likely to be of evolutionary and agronomic significance. Stomatal poles are stiff and have a distinct cell wall composition Loss of polar stiffening is associated with decreased degree of stomatal opening Lack of radial guard cell stiffening does not preclude stomatal opening A “fix and flex” model predicts more efficient opening of stomata via polar stiffening
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Affiliation(s)
- Ross Carter
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK; Department of Physics and Astronomy, University of Sheffield, Sheffield, UK; Computational and Systems Biology, John Innes Centre, Norwich, UK
| | - Hugh Woolfenden
- Computational and Systems Biology, John Innes Centre, Norwich, UK
| | - Alice Baillie
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Sam Amsbury
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Sarah Carroll
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Eleanor Healicon
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Spyros Sovatzoglou
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
| | | | - Julie E Gray
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - Jamie Hobbs
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
| | - Richard J Morris
- Computational and Systems Biology, John Innes Centre, Norwich, UK
| | - Andrew J Fleming
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.
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Shtein I, Popper ZA, Harpaz-Saad S. Permanently open stomata of aquatic angiosperms display modified cellulose crystallinity patterns. PLANT SIGNALING & BEHAVIOR 2017; 12:e1339858. [PMID: 28718691 PMCID: PMC5586356 DOI: 10.1080/15592324.2017.1339858] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Most floating aquatic plants have stomata on their upper leaf surfaces, and usually their stomata are permanently open. We previously identified 3 distinct crystallinity patterns in stomatal cell walls, with angiosperm kidney-shaped stomata having the highest crystallinity in the polar end walls as well as the adjacent polar regions of the guard cells. A numerical bio-mechanical model suggested that the high crystallinity areas are localized to regions where the highest stress is imposed. Here, stomatal cell wall crystallinity was examined in 4 floating plants from 2 different taxa: basal angiosperms from the ANITA grade and monocots. It appears that the non-functional stomata of floating plants display reduced crystallinity in the polar regions as compared with high crystallinity of the ventral (inner) walls. Thus their guard cells are both less flexible and less stress resistant. Our findings suggest that the pattern of cellulose crystallinity in stomata of floating plants from different families was altered as a consequence of similar evolutionary pressures.
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Affiliation(s)
- Ilana Shtein
- Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Zoë A. Popper
- Botany and Plant Science, Ryan Institute for Environmental, Marine and Energy Research, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Smadar Harpaz-Saad
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
- CONTACT Smadar Harpaz-Saad Plant Sciences, The Hebrew University of Jerusalem, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture Faculty of Agriculture Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 7610001, Israel
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53
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Shtein I, Shelef Y, Marom Z, Zelinger E, Schwartz A, Popper ZA, Bar-On B, Harpaz-Saad S. Stomatal cell wall composition: distinctive structural patterns associated with different phylogenetic groups. ANNALS OF BOTANY 2017; 119:1021-1033. [PMID: 28158449 PMCID: PMC5604698 DOI: 10.1093/aob/mcw275] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 12/05/2016] [Indexed: 05/18/2023]
Abstract
Background and Aims Stomatal morphology and function have remained largely conserved throughout ∼400 million years of plant evolution. However, plant cell wall composition has evolved and changed. Here stomatal cell wall composition was investigated in different vascular plant groups in attempt to understand their possible effect on stomatal function. Methods A renewed look at stomatal cell walls was attempted utilizing digitalized polar microscopy, confocal microscopy, histology and a numerical finite-elements simulation. The six species of vascular plants chosen for this study cover a broad structural, ecophysiological and evolutionary spectrum: ferns ( Asplenium nidus and Platycerium bifurcatum ) and angiosperms ( Arabidopsis thaliana and Commelina erecta ) with kidney-shaped stomata, and grasses (angiosperms, family Poaceae) with dumbbell-shaped stomata ( Sorghum bicolor and Triticum aestivum ). Key Results Three distinct patterns of cellulose crystallinity in stomatal cell walls were observed: Type I (kidney-shaped stomata, ferns), Type II (kidney-shaped stomata, angiosperms) and Type III (dumbbell-shaped stomata, grasses). The different stomatal cell wall attributes investigated (cellulose crystallinity, pectins, lignin, phenolics) exhibited taxon-specific patterns, with reciprocal substitution of structural elements in the end-walls of kidney-shaped stomata. According to a numerical bio-mechanical model, the end walls of kidney-shaped stomata develop the highest stresses during opening. Conclusions The data presented demonstrate for the first time the existence of distinct spatial patterns of varying cellulose crystallinity in guard cell walls. It is also highly intriguing that in angiosperms crystalline cellulose appears to have replaced lignin that occurs in the stomatal end-walls of ferns serving a similar wall strengthening function. Such taxon-specific spatial patterns of cell wall components could imply different biomechanical functions, which in turn could be a consequence of differences in environmental selection along the course of plant evolution.
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Affiliation(s)
- Ilana Shtein
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Yaniv Shelef
- Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Ziv Marom
- Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Einat Zelinger
- The Interdepartmental Equipment Unit, The Robert H. Smith Faculty of Agriculture, Food & Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Amnon Schwartz
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Zoë A. Popper
- Botany and Plant Science, Ryan Institute for Environmental, Marine and Energy Research, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Benny Bar-On
- Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Smadar Harpaz-Saad
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
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Sampedro J, Valdivia ER, Fraga P, Iglesias N, Revilla G, Zarra I. Soluble and Membrane-Bound β-Glucosidases Are Involved in Trimming the Xyloglucan Backbone. PLANT PHYSIOLOGY 2017; 173:1017-1030. [PMID: 27956490 PMCID: PMC5291047 DOI: 10.1104/pp.16.01713] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 12/09/2016] [Indexed: 05/23/2023]
Abstract
In many flowering plants, xyloglucan is a major component of primary cell walls, where it plays an important role in growth regulation. Xyloglucan can be degraded by a suite of exoglycosidases that remove specific sugars. In this work, we show that the xyloglucan backbone, formed by (1→4)-linked β-d-glucopyranosyl residues, can be attacked by two different Arabidopsis (Arabidopsis thaliana) β-glucosidases from glycoside hydrolase family 3. While BGLC1 (At5g20950; for β-glucosidase active against xyloglucan 1) is responsible for all or most of the soluble activity, BGLC3 (At5g04885) is usually a membrane-anchored protein. Mutations in these two genes, whether on their own or combined with mutations in other exoglycosidase genes, resulted in the accumulation of partially digested xyloglucan subunits, such as GXXG, GXLG, or GXFG. While a mutation in BGLC1 had significant effects on its own, lack of BGLC3 had only minor effects. On the other hand, double bglc1 bglc3 mutants revealed a synergistic interaction that supports a role for membrane-bound BGLC3 in xyloglucan metabolism. In addition, bglc1 bglc3 was complemented by overexpression of either BGLC1 or BGLC3 In overexpression lines, BGLC3 activity was concentrated in a microsome-enriched fraction but also was present in soluble form. Finally, both genes were generally expressed in the same cell types, although, in some cases, BGLC3 was expressed at earlier stages than BGLC1 We propose that functional specialization could explain the separate localization of both enzymes, as a membrane-bound β-glucosidase could specifically digest soluble xyloglucan without affecting the wall-bound polymer.
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Affiliation(s)
- Javier Sampedro
- Departemento Biología Funcional, Facultad de Biología, Universidad de Santiago, Santiago de Compostela, 15782 Spain
| | - Elene R Valdivia
- Departemento Biología Funcional, Facultad de Biología, Universidad de Santiago, Santiago de Compostela, 15782 Spain
| | - Patricia Fraga
- Departemento Biología Funcional, Facultad de Biología, Universidad de Santiago, Santiago de Compostela, 15782 Spain
| | - Natalia Iglesias
- Departemento Biología Funcional, Facultad de Biología, Universidad de Santiago, Santiago de Compostela, 15782 Spain
| | - Gloria Revilla
- Departemento Biología Funcional, Facultad de Biología, Universidad de Santiago, Santiago de Compostela, 15782 Spain
| | - Ignacio Zarra
- Departemento Biología Funcional, Facultad de Biología, Universidad de Santiago, Santiago de Compostela, 15782 Spain
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55
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John SP, Hasenstein KH. The role of peltate scales in desiccation tolerance of Pleopeltis polypodioides. PLANTA 2017; 245:207-220. [PMID: 27928638 DOI: 10.1007/s00425-016-2631-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 11/30/2016] [Indexed: 05/14/2023]
Abstract
The extreme drought tolerance of the resurrection fern is in part the result of the dorsal scales that assist in water distribution and controlled desiccation. We studied the effect of peltate scales on water uptake and loss of the desiccation-tolerant epiphytic fern Pleopeltis polypodioides using optical and FTIR microscopy and staining with calcofluor, solophenyl flavine7GFE, and Ruthenium Red. We provide information on structure, property, and function of the scales by measuring water uptake and dehydration, contact angles, and metabolic activity. Peltate scales mainly contain cellulose, xylogalactans, and pectin. Water is absorbed from the center of scales, and the overlapping arrangement of scales facilitates surface spreading of water. Intact fronds hydrated fully within 5 h of imbibition of the apical pinna, without scales water uptake stopped after 1 h. Hydration rates via rhizomes followed a longer time course but also improved in the presence of scales. Fronds with and without scales lost half of their water content in 15 or 4 h, respectively. The overall metabolism of rapidly dehydrated fronds was significantly reduced compared with slowly dehydrated fronds. Thus, water management and metabolism of Pleopeltis are dependent on surface properties determined by peltate scales.
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Affiliation(s)
- Susan P John
- Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, 70503, USA
| | - Karl H Hasenstein
- Department of Biology, University of Louisiana at Lafayette, Lafayette, LA, 70503, USA.
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56
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Li S, Wang KW. Plant-inspired adaptive structures and materials for morphing and actuation: a review. BIOINSPIRATION & BIOMIMETICS 2016; 12:011001. [PMID: 27995902 DOI: 10.1088/1748-3190/12/1/011001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Plants exhibit a variety of reversible motions, from the slow opening of pine cones to the impulsive closing of Venus flytrap leaves. These motions are achieved without muscles and they have inspired a wide spectrum of engineered materials and structures. This review summarizes the recent developments of plant-inspired adaptive structures and materials for morphing and actuation. We begin with a brief overview of the actuation strategies and physiological features associated to these plant movements, showing that different combinations of these strategies and features can lead to motions with different deformation characteristics and response speeds. Then we offer a comprehensive survey of the plant-inspired morphing and actuation systems, including pressurized cellular structures, osmotic actuation, anisotropic hygroscopic materials, and bistable systems for rapid movements. Although these engineered systems are vastly different in terms of their size scales and intended applications, their working principles are all related to the actuation strategies and physiological features in plants. This review is to promote future cross-disciplinary studies between plant biology and engineering, which can foster new solutions for many applications such as morphing airframes, soft robotics and kinetic architectures.
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Affiliation(s)
- Suyi Li
- Department of Mechanical Engineering, Clemson University, Clemson, SC, 29634, USA
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57
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Amsbury S, Hunt L, Elhaddad N, Baillie A, Lundgren M, Verhertbruggen Y, Scheller HV, Knox JP, Fleming AJ, Gray JE. Stomatal Function Requires Pectin De-methyl-esterification of the Guard Cell Wall. Curr Biol 2016; 26:2899-2906. [PMID: 27720618 PMCID: PMC5106435 DOI: 10.1016/j.cub.2016.08.021] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 07/06/2016] [Accepted: 08/05/2016] [Indexed: 12/12/2022]
Abstract
Stomatal opening and closure depends on changes in turgor pressure acting within guard cells to alter cell shape [1]. The extent of these shape changes is limited by the mechanical properties of the cells, which will be largely dependent on the structure of the cell walls. Although it has long been observed that guard cells are anisotropic due to differential thickening and the orientation of cellulose microfibrils [2], our understanding of the composition of the cell wall that allows them to undergo repeated swelling and deflation remains surprisingly poor. Here, we show that the walls of guard cells are rich in un-esterified pectins. We identify a pectin methylesterase gene, PME6, which is highly expressed in guard cells and required for stomatal function. pme6-1 mutant guard cells have walls enriched in methyl-esterified pectin and show a decreased dynamic range in response to triggers of stomatal opening/closure, including elevated osmoticum, suggesting that abrogation of stomatal function reflects a mechanical change in the guard cell wall. Altered stomatal function leads to increased conductance and evaporative cooling, as well as decreased plant growth. The growth defect of the pme6-1 mutant is rescued by maintaining the plants in elevated CO2, substantiating gas exchange analyses, indicating that the mutant stomata can bestow an improved assimilation rate. Restoration of PME6 rescues guard cell wall pectin methyl-esterification status, stomatal function, and plant growth. Our results establish a link between gene expression in guard cells and their cell wall properties, with a corresponding effect on stomatal function and plant physiology. The guard cell wall is distinguished by a relatively low level of methylated pectin Increased methyl pectin leads to stomata with a smaller dynamic range of movement These plants show increased evaporative cooling and decreased growth under drought Elevated CO2 restores mutant plant growth to normal
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Affiliation(s)
- Sam Amsbury
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Lee Hunt
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Nagat Elhaddad
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK; Department of Botany, University of Omar Al-Mukhtar, Al-Baida, Libya
| | - Alice Baillie
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Marjorie Lundgren
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Yves Verhertbruggen
- Biological Systems and Engineering Division and Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Henrik V Scheller
- Biological Systems and Engineering Division and Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - J Paul Knox
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Andrew J Fleming
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
| | - Julie E Gray
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.
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58
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Rui Y, Yi H, Kandemir B, Wang JZ, Puri VM, Anderson CT. Integrating cell biology, image analysis, and computational mechanical modeling to analyze the contributions of cellulose and xyloglucan to stomatal function. PLANT SIGNALING & BEHAVIOR 2016; 11:e1183086. [PMID: 27220916 PMCID: PMC4973784 DOI: 10.1080/15592324.2016.1183086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Cell walls are likely to be essential determinants of the amazing strength and flexibility of the guard cells that surround each stomatal pore in plants, but surprisingly little is known about cell wall composition, organization, and dynamics in guard cells. Recent analyses of cell wall organization and stomatal function in the guard cells of Arabidopsis thaliana mutants with defects in cellulose and xyloglucan have allowed for the development of new hypotheses about the relative contributions of these components to guard cell function. Advanced image analysis methods can allow for the automated detection of key structures, such as microtubules (MTs) and Cellulose Synthesis Complexes (CSCs), in guard cells, to help determine their contributions to stomatal function. A major challenge in the mechanical modeling of dynamic biological structures, such as guard cell walls, is to connect nanoscale features (e.g., wall polymers and their molecular interactions) with cell-scale mechanics; this challenge can be addressed by applying multiscale computational modeling that spans multiple spatial scales and physical attributes for cell walls.
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Affiliation(s)
- Yue Rui
- Department of Biology, The Pennsylvania State University, University Park, PA, USA
- Plant Biology Interdepartmental Graduate Program, The Pennsylvania State University, University Park, PA, USA
| | - Hojae Yi
- Department of Agricultural and Biological Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Baris Kandemir
- College of Information Sciences and Technology, The Pennsylvania State University, University Park, PA, USA
| | - James Z. Wang
- College of Information Sciences and Technology, The Pennsylvania State University, University Park, PA, USA
| | - Virendra M. Puri
- Department of Agricultural and Biological Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Charles T. Anderson
- Department of Biology, The Pennsylvania State University, University Park, PA, USA
- Center for Lignocellulose Structure and Formation, The Pennsylvania State University, University Park, PA, USA
- CONTACT Charles T. Anderson
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