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Woolfenden HC, Bourdais G, Kopischke M, Miedes E, Molina A, Robatzek S, Morris RJ. A computational approach for inferring the cell wall properties that govern guard cell dynamics. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 92:5-18. [PMID: 28741858 PMCID: PMC5637902 DOI: 10.1111/tpj.13640] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/08/2017] [Accepted: 07/13/2017] [Indexed: 05/02/2023]
Abstract
Guard cells dynamically adjust their shape in order to regulate photosynthetic gas exchange, respiration rates and defend against pathogen entry. Cell shape changes are determined by the interplay of cell wall material properties and turgor pressure. To investigate this relationship between turgor pressure, cell wall properties and cell shape, we focused on kidney-shaped stomata and developed a biomechanical model of a guard cell pair. Treating the cell wall as a composite of the pectin-rich cell wall matrix embedded with cellulose microfibrils, we show that strong, circumferentially oriented fibres are critical for opening. We find that the opening dynamics are dictated by the mechanical stress response of the cell wall matrix, and as the turgor rises, the pectinaceous matrix stiffens. We validate these predictions with stomatal opening experiments in selected Arabidopsis cell wall mutants. Thus, using a computational framework that combines a 3D biomechanical model with parameter optimization, we demonstrate how to exploit subtle shape changes to infer cell wall material properties. Our findings reveal that proper stomatal dynamics are built on two key properties of the cell wall, namely anisotropy in the form of hoop reinforcement and strain stiffening.
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Affiliation(s)
- Hugh C. Woolfenden
- Computational and Systems BiologyJohn Innes CentreNorwich Research ParkNorwichNR4 7UHUK
| | - Gildas Bourdais
- The Sainsbury LaboratoryNorwich Research ParkNorwichNR4 7UHUK
| | | | - Eva Miedes
- Centro de Biotecnología y Genómica de Plantas (CBGP)Universidad Politécnica de Madrid (UPM)Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)Campus de Montegancedo UPM28223Pozuelo de AlarcónMadridSpain
- Departamento de Biotecnología‐Biología VegetalEscuela Técnica Superior de Ingeniería AgrónomicaAlimentaria y de Biosistemas, UPM28040MadridSpain
| | - Antonio Molina
- Centro de Biotecnología y Genómica de Plantas (CBGP)Universidad Politécnica de Madrid (UPM)Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)Campus de Montegancedo UPM28223Pozuelo de AlarcónMadridSpain
- Departamento de Biotecnología‐Biología VegetalEscuela Técnica Superior de Ingeniería AgrónomicaAlimentaria y de Biosistemas, UPM28040MadridSpain
| | - Silke Robatzek
- The Sainsbury LaboratoryNorwich Research ParkNorwichNR4 7UHUK
| | - Richard J. Morris
- Computational and Systems BiologyJohn Innes CentreNorwich Research ParkNorwichNR4 7UHUK
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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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Konopka-Postupolska D, Clark G. Annexins as Overlooked Regulators of Membrane Trafficking in Plant Cells. Int J Mol Sci 2017; 18:E863. [PMID: 28422051 PMCID: PMC5412444 DOI: 10.3390/ijms18040863] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 04/03/2017] [Accepted: 04/06/2017] [Indexed: 12/11/2022] Open
Abstract
Annexins are an evolutionary conserved superfamily of proteins able to bind membrane phospholipids in a calcium-dependent manner. Their physiological roles are still being intensively examined and it seems that, despite their general structural similarity, individual proteins are specialized toward specific functions. However, due to their general ability to coordinate membranes in a calcium-sensitive fashion they are thought to participate in membrane flow. In this review, we present a summary of the current understanding of cellular transport in plant cells and consider the possible roles of annexins in different stages of vesicular transport.
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Affiliation(s)
- Dorota Konopka-Postupolska
- Plant Biochemistry Department, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw 02-106, Poland.
| | - Greg Clark
- Molecular, Cell, and Developmental Biology, University of Texas, Austin, TX 78712, USA.
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Rui Y, Anderson CT. Functional Analysis of Cellulose and Xyloglucan in the Walls of Stomatal Guard Cells of Arabidopsis. PLANT PHYSIOLOGY 2016; 170:1398-419. [PMID: 26729799 PMCID: PMC4775103 DOI: 10.1104/pp.15.01066] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 01/03/2016] [Indexed: 05/18/2023]
Abstract
Stomatal guard cells are pairs of specialized epidermal cells that control water and CO2 exchange between the plant and the environment. To fulfill the functions of stomatal opening and closure that are driven by changes in turgor pressure, guard cell walls must be both strong and flexible, but how the structure and dynamics of guard cell walls enable stomatal function remains poorly understood. To address this question, we applied cell biological and genetic analyses to investigate guard cell walls and their relationship to stomatal function in Arabidopsis (Arabidopsis thaliana). Using live-cell spinning disk confocal microscopy, we measured the motility of cellulose synthase (CESA)-containing complexes labeled by green fluorescent protein (GFP)-CESA3 and observed a reduced proportion of GFP-CESA3 particles colocalizing with microtubules upon stomatal closure. Imaging cellulose organization in guard cells revealed a relatively uniform distribution of cellulose in the open state and a more fibrillar pattern in the closed state, indicating that cellulose microfibrils undergo dynamic reorganization during stomatal movements. In cesa3(je5) mutants defective in cellulose synthesis and xxt1 xxt2 mutants lacking the hemicellulose xyloglucan, stomatal apertures, changes in guard cell length, and cellulose reorganization were aberrant during fusicoccin-induced stomatal opening or abscisic acid-induced stomatal closure, indicating that sufficient cellulose and xyloglucan are required for normal guard cell dynamics. Together, these results provide new insights into how guard cell walls allow stomata to function as responsive mediators of gas exchange at the plant surface.
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Affiliation(s)
- Yue Rui
- Department of Biology (Y.R., C.T.A.) and Center for Lignocellulose Structure and Formation (C.T.A.), Pennsylvania State University, University Park, Pennsylvania 16802
| | - Charles T Anderson
- Department of Biology (Y.R., C.T.A.) and Center for Lignocellulose Structure and Formation (C.T.A.), Pennsylvania State University, University Park, Pennsylvania 16802
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Polevova S, Breygina M, Matveyeva N, Yermakov I. Periplasmic multilamellar membranous structures in Nicotiana tabacum L. pollen grains treated with Ni²⁺ or Cu²⁺. PROTOPLASMA 2014; 251:1521-5. [PMID: 24802108 DOI: 10.1007/s00709-014-0651-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 04/18/2014] [Indexed: 06/03/2023]
Abstract
Essential trace elements Ni(2+) and Cu(2+) can block pollen germination without causing cell death. Mechanisms of this effect remain unclear. Using TEM, we studied the effects of Ni(2+) or Cu(2+) treatment on the ultrastructure of the aperture regions in tobacco pollen preparing to germinate in vitro, since in these zones, the main fluxes of water, ions, and metabolites cross the plasmalemma. Neither Ni(2+) nor Cu(2+) altered the cytoplasm ultrastructure, but both affected the reorganization of apertural periplasm during pollen activation. Numerous multilamellar membranous structures continuous with the plasma membrane could be seen in hydrated but not yet activated pollen. When the normal activation was completed, the structures disappeared and the plasmalemma became smooth. In the presence of 1 mM Ni(2+) or 100 μM Cu(2+), these structures preserved its original appearance. It is assumed to be the storage form for the membrane material, which is to provide an initial phase of the pollen tube growth. Ni(2+) and Cu(2+) affect the utilization of these membranes, thereby, blocking the pollen germination.
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Affiliation(s)
- Svetlana Polevova
- Higher Plants Department, Faculty of Biology, Lomonosov Moscow State University, Lenin Hills, Moscow, Russia, 119234,
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Staykova M, Stone HA. The role of the membrane confinement in the surface area regulation of cells. Commun Integr Biol 2014. [DOI: 10.4161/cib.16854] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Liu Q, Qiao F, Ismail A, Chang X, Nick P. The plant cytoskeleton controls regulatory volume increase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2111-20. [PMID: 23660128 DOI: 10.1016/j.bbamem.2013.04.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 04/28/2013] [Accepted: 04/30/2013] [Indexed: 01/08/2023]
Abstract
The ability to adjust cell volume is required for the adaptation to osmotic stress. Plant protoplasts can swell within seconds in response to hypoosmotic shock suggesting that membrane material is released from internal stores. Since the stability of plant membranes depends on submembraneous actin, we asked, whether this regulatory volume control depends on the cytoskeleton. As system we used two cell lines from grapevine which differ in their osmotic tolerance and observed that the cytoskeleton responded differently in these two cell lines. To quantify the ability for regulatory volume control, we used hydraulic conductivity (Lp) as readout and demonstrated a role of the cytoskeleton in protoplast swelling. Chelation of calcium, inhibition of calcium channels, or manipulation of membrane fluidity, did not significantly alter Lp, whereas direct manipulation of the cytoskeleton via specific chemical reagents, or indirectly, through the bacterial elicitor Harpin or activation of phospholipase D, was effective. By optochemical engineering of actin using a caged form of the phytohormone auxin we can break the symmetry of actin organisation resulting in a localised deformation of cell shape indicative of a locally increased Lp. We interpret our findings in terms of a model, where the submembraneous cytoskeleton controls the release of intracellular membrane stores during regulatory volume change.
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Affiliation(s)
- Qiong Liu
- Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology, Kaiserstr. 2, 76128 Karlsruhe, Germany.
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Staykova M, Stone HA. The role of the membrane confinement in the surface area regulation of cells. Commun Integr Biol 2011; 4:616-8. [PMID: 22046479 DOI: 10.4161/cib.4.5.16854] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 06/08/2011] [Indexed: 11/19/2022] Open
Abstract
We propose a new in vitro system to study the mechanics of surface area regulation in cells, which takes into an account the spatial confinement of the cell membrane. By coupling a lipid bilayer to the strain-controlled deformation of an elastic sheet, we show that upon straining the supported lipid bilayer expands its surface area by absorbing adherent lipid vesicles and upon compression decreases its area by expelling lipid tubes out of its plane. The processes are reversible and closely resemble in vivo observations on shrinking cells. Our results suggest that the mechanics of the area regulation in cells is controlled primarily by the membrane tension and the effects of the membrane confinement.
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Affiliation(s)
- Margarita Staykova
- Department of Mechanical and Aerospace Engineering; Princeton University; Princeton, NJ USA
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Wang XL, Gao XQ, Wang XC. Stochastic dynamics of actin filaments in guard cells regulating chloroplast localization during stomatal movement. PLANT, CELL & ENVIRONMENT 2011; 34:1248-57. [PMID: 21443604 DOI: 10.1111/j.1365-3040.2011.02325.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Actin filaments and chloroplasts in guard cells play roles in stomatal function. However, detailed actin dynamics vary, and the roles that they play in chloroplast localization during stomatal movement remain to be determined. We examined the dynamics of actin filaments and chloroplast localization in transgenic tobacco expressing green fluorescent protein (GFP)-mouse talin in guard cells by time-lapse imaging. Actin filaments showed sliding, bundling and branching dynamics in moving guard cells. During stomatal movement, long filaments can be severed into small fragments, which can form longer filaments by end-joining activities. With chloroplast movement, actin filaments near chloroplasts showed severing and elongation activity in guard cells during stomatal movement. Cytochalasin B treatment abolished elongation, bundling and branching activities of actin filaments in guard cells, and these changes of actin filaments, and as a result, more chloroplasts were localized at the centre of guard cells. However, chloroplast turning to avoid high light, and sliding of actin fragments near the chloroplast, was unaffected following cytochalasin B treatment in guard cells. We suggest that the sliding dynamics of actin may play roles in chloroplast turning in guard cells. Our results indicate that the stochastic dynamics of actin filaments in guard cells regulate chloroplast localization during stomatal movement.
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Affiliation(s)
- Xiu-Ling Wang
- State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian 271018, China
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Mechanics of surface area regulation in cells examined with confined lipid membranes. Proc Natl Acad Sci U S A 2011; 108:9084-8. [PMID: 21562210 DOI: 10.1073/pnas.1102358108] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Cells are wrapped in inelastic membranes, yet they can sustain large mechanical strains by regulating their area. The area regulation in cells is achieved either by membrane folding or by membrane exo- and endocytosis. These processes involve complex morphological transformations of the cell membrane, i.e., invagination, vesicle fusion, and fission, whose precise mechanisms are still under debate. Here we provide mechanistic insights into the area regulation of cell membranes, based on the previously neglected role of membrane confinement, as well as on the strain-induced membrane tension. Commonly, the membranes of mammalian and plant cells are not isolated, but rather they are adhered to an extracellular matrix, the cytoskeleton, and to other cell membranes. Using a lipid bilayer, coupled to an elastic sheet, we are able to demonstrate that, upon straining, the confined membrane is able to regulate passively its area. In particular, by stretching the elastic support, the bilayer laterally expands without rupture by fusing adhered lipid vesicles; upon compression, lipid tubes grow out of the membrane plane, thus reducing its area. These transformations are reversible, as we show using cycles of expansion and compression, and closely reproduce membrane processes found in cells during area regulation. Moreover, we demonstrate a new mechanism for the formation of lipid tubes in cells, which is driven by the membrane lateral compression and may therefore explain the various membrane tubules observed in shrinking cells.
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Li B, Xie M, Sun M, Jia W. How does plasmalemma surface area accommodate alterations in guard cell volume during stomatal closing? PLANT SIGNALING & BEHAVIOR 2010; 5:1468-1469. [PMID: 21051937 PMCID: PMC3115257 DOI: 10.4161/psb.5.11.13470] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Accepted: 08/28/2010] [Indexed: 05/30/2023]
Abstract
During stomatal movement, guard cells undergo considerable and repetitive variations in cell volume and consequently surface area over a period of minutes. Due to limited stretching capability of the plasmalemma, alterations in the surface area must accommodate the volume changes through membrane turnover. Using fluorescence imaging and electrophysiology techniques, extensive studies imply that endocytosis may be a critical mechanism for the plasmalemma turnover. In contrast to the conventional studies, using transmission electronic microscope in combination with laser confocal microscope so that the membrane turnover can be detected without a resolution limitation, our works, recently published in Journal of Experimental Botany, has provided strong evidences that excretion and folding of plasmalemma are critical for the accommodation of the cell volume alterations in intact guard cells in Vicia faba L. These results have opened a new perspective on the mechanism for the membrane turnover during stomatal movement. In this addendum, we further discuss some key issues about the mechanisms for the accommodation of the cell volume alterations during stomatal movements.
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Affiliation(s)
- Bingbing Li
- College of Agronomy and Biotechnology, China Agricultural University, Beijing, China
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