scholarly journals Xyloglucan remodelling defines differential tissue expansion in plants

2019 ◽  
Author(s):  
Silvia Melina Velasquez ◽  
Xiaoyuan Guo ◽  
Marçal Gallemi ◽  
Bibek Aryal ◽  
Peter Venhuizen ◽  
...  
Keyword(s):  
Cell Wall ◽  
Growth Control ◽  
Size Control ◽  
Tissue Expansion ◽  
Central Importance ◽  
Hypocotyl Growth ◽  
Differential Growth ◽  
Rigid Cell Wall ◽  
Genetic Interference ◽  
Cell Wall Mechanics

Size control is a fundamental question in biology, showing incremental complexity in case of plants whose cells possess a rigid cell wall. The phytohormone auxin is a vital growth regulator with central importance for differential growth control. Here we show that growth inducing and repressing auxin conditions correlate with reduced and enhanced complexity of extracellular xyloglucans, respectively. In agreement, genetic interference with xyloglucan complexity distinctly modulates auxin-dependent differential growth rates. Our work proposes that an auxin-dependent, spatially defined effect on xyloglucan structure and its effect on cell wall mechanics specify differential, gravitropic hypocotyl growth.

scholarly journals Xyloglucan Remodeling Defines Auxin-Dependent Differential Tissue Expansion in Plants

2021 ◽  
Vol 22 (17) ◽  
pp. 9222 ◽  
Author(s):  
Silvia Melina Velasquez ◽  
Xiaoyuan Guo ◽  
Marçal Gallemi ◽  
Bibek Aryal ◽  
Peter Venhuizen ◽  
...  
Keyword(s):  
Cell Wall ◽  
Growth Control ◽  
Size Control ◽  
Tissue Expansion ◽  
Major Type ◽  
Hypocotyl Growth ◽  
Differential Growth ◽  
Rigid Cell Wall ◽  
Molecular Complexity ◽  
Genetic Interference

Size control is a fundamental question in biology, showing incremental complexity in plants, whose cells possess a rigid cell wall. The phytohormone auxin is a vital growth regulator with central importance for differential growth control. Our results indicate that auxin-reliant growth programs affect the molecular complexity of xyloglucans, the major type of cell wall hemicellulose in eudicots. Auxin-dependent induction and repression of growth coincide with reduced and enhanced molecular complexity of xyloglucans, respectively. In agreement with a proposed function in growth control, genetic interference with xyloglucan side decorations distinctly modulates auxin-dependent differential growth rates. Our work proposes that auxin-dependent growth programs have a spatially defined effect on xyloglucan’s molecular structure, which in turn affects cell wall mechanics and specifies differential, gravitropic hypocotyl growth.

scholarly journals Anisotropic growth is achieved through the additive mechanical effect of material anisotropy and elastic asymmetry

2018 ◽  
Author(s):  
Firas Bou Daher ◽  
Yuanjie Chen ◽  
Behruz Bozorg ◽  
Jack Clough ◽  
Henrik Jönsson ◽  
...  
Keyword(s):  
Cell Wall ◽  
Growth Characteristic ◽  
Growth Control ◽  
Mechanical Effect ◽  
Anisotropic Growth ◽  
Hypocotyl Growth ◽  
Differential Growth ◽  
Directional Growth ◽  
Additive Combination ◽  
Shoot Meristems

AbstractFast directional growth is a necessity for the young seedling: after germination, the seedling needs to quickly reach through the soil to begin its autotrophic life. In most dicot plants, this rapid escape is due to the anisotropic elongation of the hypocotyl, the columnar organ between the root and the shoot meristems. Such anisotropic growth is common in many plant organs and is canonically attributed to cell wall anisotropy produced by oriented cellulose fibers in the cell wall. More recently, a mechanism based on asymmetric cell wall elasticity has been proposed, produced by differential pectin biochemistry. Here we present a harmonizing model for anisotropic growth control in the dark-grown Arabidopsis hypocotyl: basic anisotropic information is provided by cellulose orientation (proxied by microtubules) and additive anisotropic information is provided by pectin-based elastic asymmetry in the epidermis. We demonstrate that hypocotyl growth was always anisotropic with axial and transverse walls growing differently, from germination. We present experimental evidence for pectin biochemical differences and wall mechanics underlying this differential growth. We demonstrate that pectin biochemical changes control the transition to rapid growth characteristic of Arabidopsis hypocotyl elongation, and provide evidence for a substantial mechanical role for pectin in the cell wall when microtubules are compromised. Lastly, our in silico modelling experiments indicate an additive combination for pectin biochemistry and cellulose orientation in promoting anisotropic growth.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

scholarly journals Determination of organ size: a need to focus on growth rate, not size

2020 ◽  
Vol 64 (4-5-6) ◽  
pp. 299-318
Author(s):  
Carmen M.A. Coelho
Keyword(s):  
Control Mechanism ◽  
Growth Control ◽  
Size Control ◽  
Organ Size ◽  
Cell Competition ◽  
The Past ◽  
Mechanistic Basis ◽  
Regulation Of Growth ◽  
Correct Size

The regulation of growth and the determination of organ-size in animals is an area of research that has received much attention during the past two and a half decades. Classic regeneration and cell-competition studies performed during the last century suggested that for size to be determined, organ-size is sensed and this sense of size feeds back into the growth control mechanism such that growth stops at the “correct” size. Recent work using Drosophila imaginal discs as a system has provided a particularly detailed cellular and molecular understanding of growth. Yet, a clear mechanistic basis for size-sensing has not emerged. I re-examine these studies from a different perspective and ask whether there is scope for alternate modes of size control in which size does not need to be sensed.

scholarly journals Even Visually Intact Cell Walls in Waterlogged Archaeological Wood Are Chemically Deteriorated and Mechanically Fragile: A Case of a 170 Year-Old Shipwreck

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1113 ◽  
Author(s):  
Liuyang Han ◽  
Xingling Tian ◽  
Tobias Keplinger ◽  
Haibin Zhou ◽  
Ren Li ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Walls ◽  
Intact Cell ◽  
Nitrogen Adsorption ◽  
Wet Chemistry ◽  
Archaeological Wood ◽  
Waterlogged Archaeological Wood ◽  
X Ray Scattering ◽  
Crystallite Structure ◽  
Cell Wall Mechanics

Structural and chemical deterioration and its impact on cell wall mechanics were investigated for visually intact cell walls (VICWs) in waterlogged archaeological wood (WAW). Cell wall mechanical properties were examined by nanoindentation without prior embedding. WAW showed more than 25% decrease of both hardness and elastic modulus. Changes of cell wall composition, cellulose crystallite structure and porosity were investigated by ATR-FTIR imaging, Raman imaging, wet chemistry, 13C-solid state NMR, pyrolysis-GC/MS, wide angle X-ray scattering, and N2 nitrogen adsorption. VICWs in WAW possessed a cleavage of carboxyl in side chains of xylan, a serious loss of polysaccharides, and a partial breakage of β-O-4 interlinks in lignin. This was accompanied by a higher amount of mesopores in cell walls. Even VICWs in WAW were severely deteriorated at the nanoscale with impact on mechanics, which has strong implications for the conservation of archaeological shipwrecks.

Growth Control and Cell Wall Signaling in Plants

2012 ◽  
Vol 63 (1) ◽  
pp. 381-407 ◽  
Author(s):  
Sebastian Wolf ◽  
Kian Hématy ◽  
Herman Höfte
Keyword(s):  
Cell Wall ◽  
Growth Control

Methods to quantify primary plant cell wall mechanics

2019 ◽  
Vol 70 (14) ◽  
pp. 3615-3648 ◽  
Author(s):  
Amir J Bidhendi ◽  
Anja Geitmann
Keyword(s):  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Polymer Network ◽  
Plant Cells ◽  
Tensile Tests ◽  
Mechanical Modeling ◽  
Experimental Conditions ◽  
Testing Techniques ◽  
Cell Wall Mechanics

Abstract The primary plant cell wall is a dynamically regulated composite material of multiple biopolymers that forms a scaffold enclosing the plant cells. The mechanochemical make-up of this polymer network regulates growth, morphogenesis, and stability at the cell and tissue scales. To understand the dynamics of cell wall mechanics, and how it correlates with cellular activities, several experimental frameworks have been deployed in recent years to quantify the mechanical properties of plant cells and tissues. Here we critically review the application of biomechanical tool sets pertinent to plant cell mechanics and outline some of their findings, relevance, and limitations. We also discuss methods that are less explored but hold great potential for the field, including multiscale in silico mechanical modeling that will enable a unified understanding of the mechanical behavior across the scales. Our overview reveals significant differences between the results of different mechanical testing techniques on plant material. Specifically, indentation techniques seem to consistently report lower values compared with tensile tests. Such differences may in part be due to inherent differences among the technical approaches and consequently the wall properties that they measure, and partly due to differences between experimental conditions.

An extensin peroxidase is associated with white-light inhibition of lupin (Lupinus albus) hypocotyl growth

1999 ◽  
Vol 26 (1) ◽  
pp. 29 ◽  
Author(s):  
P. Jackson ◽  
S. Paulo ◽  
C. P. P. Ricardo ◽  
M. Brownleader ◽  
P. O. Freire
Keyword(s):  
Cell Wall ◽  
White Light ◽  
Cell Expansion ◽  
Structural Changes ◽  
Lupinus Albus ◽  
Extension Rate ◽  
Hypocotyl Growth ◽  
Cross Links ◽  
Quantitative Changes

The spatial distribution of the major basic (B2; pI 8.8) peroxidase of the intercellular fluid has an inverse relation with extension rate in etiolated hypocotyls of Lupinus albus L., suggesting its possible role in the control of cell expansion. White-light irradiation of etiolated hypocotyls resulted in growth inhibition and the induction of B2 and acidic (A2, pI 4.7–5.2) isoperoxidases (EC 1.1.11.7) to higher physiological activities. However, only the activities of the B2 isoperoxidases underwent quantitative changes in both space and time which suggested their role in growth-retardation. We have purified the B2 and A2 (pI 5.2) peroxidases to apparent electrophoretic homogeneity. To corroborate evidence obtained elsewhere that growth cessation coincides with cell wall structural changes and cell wall rigidification, we have shown that the B2 peroxidase, and not A2 peroxidase, cross-links tomato extensin in vitro. The B2 peroxidase may therefore catalyse the developmentally and light regulated formation of a covalently cross-linked cell wall extensin matrix in lupin hypocotyls. The cell wall would be more rigid or more recalcitrant to wall-loosening and subsequently contribute to the control of cell expansion.

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