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.

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

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Firas Bou Daher ◽  
Yuanjie Chen ◽  
Behruz Bozorg ◽  
Jack Clough ◽  
Henrik Jönsson ◽  
...  
Keyword(s):  
Cell Wall ◽  
Growth Regulation ◽  
Growth Control ◽  
Cellulose Fibers ◽  
Mechanical Effect ◽  
Anisotropic Growth ◽  
Material Anisotropy ◽  
Directional Growth ◽  
Cell Wall Elasticity ◽  
Shoot Meristems

Fast directional growth is a necessity for the young seedling; after germination, it needs to quickly penetrate 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. Anisotropic growth is common in plant organs and is canonically attributed to cell wall anisotropy produced by oriented cellulose fibers. Recently, a mechanism based on asymmetric pectin-based cell wall elasticity has been proposed. Here we present a harmonizing model for anisotropic growth control in the dark-grown Arabidopsis thaliana hypocotyl: basic anisotropic information is provided by cellulose orientation) and additive anisotropic information is provided by pectin-based elastic asymmetry in the epidermis. We quantitatively show that hypocotyl elongation is anisotropic starting at germination. We present experimental evidence for pectin biochemical differences and wall mechanics providing important growth regulation in the hypocotyl. Lastly, our in silico modelling experiments indicate an additive collaboration between pectin biochemistry and cellulose orientation in promoting anisotropic 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 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.

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

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.

scholarly journals The Proline-Rich Family Protein EXTENSIN33 Is Required for Etiolated Arabidopsis thaliana Hypocotyl Growth

2020 ◽  
Vol 61 (6) ◽  
pp. 1191-1203 ◽  
Author(s):  
Malgorzata Zdanio ◽  
Agnieszka Karolina Boron ◽  
Daria Balcerowicz ◽  
Sébastjen Schoenaers ◽  
Marios Nektarios Markakis ◽  
...  
Keyword(s):  
Cell Wall ◽  
Reverse Genetics ◽  
Constant Load ◽  
Hypocotyl Growth ◽  
Native Promoter ◽  
Family Protein ◽  
Altered Cell ◽  
The Moment ◽  
Elongation Phase ◽  
Mutant Lines

Abstract Growth of etiolated Arabidopsis hypocotyls is biphasic. During the first phase, cells elongate slowly and synchronously. At 48 h after imbibition, cells at the hypocotyl base accelerate their growth. Subsequently, this rapid elongation propagates through the hypocotyl from base to top. It is largely unclear what regulates the switch from slow to fast elongation. Reverse genetics-based screening for hypocotyl phenotypes identified three independent mutant lines of At1g70990, a short extensin (EXT) family protein that we named EXT33, with shorter etiolated hypocotyls during the slow elongation phase. However, at 72 h after imbibition, these dark-grown mutant hypocotyls start to elongate faster than the wild type (WT). As a result, fully mature 8-day-old dark-grown hypocotyls were significantly longer than WTs. Mutant roots showed no growth phenotype. In line with these results, analysis of native promoter-driven transcriptional fusion lines revealed that, in dark-grown hypocotyls, expression occurred in the epidermis and cortex and that it was strongest in the growing part. Confocal and spinning disk microscopy on C-terminal protein-GFP fusion lines localized the EXT33-protein to the ER and cell wall. Fourier-transform infrared microspectroscopy identified subtle changes in cell wall composition between WT and the mutant, reflecting altered cell wall biomechanics measured by constant load extensometry. Our results indicate that the EXT33 short EXT family protein is required during the first phase of dark-grown hypocotyl elongation and that it regulates the moment and extent of the growth acceleration by modulating cell wall extensibility.

Anisotropic Growth Control of Polyaniline Nanostructures and Their Morphology-Dependent Electrochemical Characteristics

ACS Nano ◽  
2012 ◽  
Vol 6 (9) ◽  
pp. 7624-7633 ◽  
Author(s):  
Hyun-Woo Park ◽  
Taejoon Kim ◽  
Jinyoung Huh ◽  
Minjeong Kang ◽  
Ji Eun Lee ◽  
...  
Keyword(s):  
Growth Control ◽  
Electrochemical Characteristics ◽  
Anisotropic Growth

Growth control by cell wall pectins

PROTOPLASMA ◽  
2012 ◽  
Vol 249 (S2) ◽  
pp. 169-175 ◽  
Author(s):  
Sebastian Wolf ◽  
Steffen Greiner
Keyword(s):  
Cell Wall ◽  
Growth Control

scholarly journals A Fungus-Specific Ras Homolog Contributes to the Hyphal Growth and Virulence of Aspergillus fumigatus

2005 ◽  
Vol 4 (12) ◽  
pp. 1982-1989 ◽  
Author(s):  
Jarrod R. Fortwendel ◽  
Wei Zhao ◽  
Ruchi Bhabhra ◽  
Steven Park ◽  
David S. Perlin ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Growth Control ◽  
Biomass Accumulation ◽  
Hyphal Growth ◽  
Pathogenic Fungi ◽  
Total Biomass ◽  
Gene Encoding ◽  
Directional Growth ◽  
Solid Media ◽  
Hyphal Morphology

ABSTRACT The Ras family of GTPase proteins has been shown to control morphogenesis in many organisms, including several species of pathogenic fungi. In a previous study, we identified a gene encoding a fungus-specific Ras subfamily homolog, rasB, in Aspergillus fumigatus. Here we report that deletion of A. fumigatus rasB caused decreased germination and growth rates on solid media but had no effect on total biomass accumulation after 24 h of growth in liquid culture. The ΔrasB mutant had an irregular hyphal morphology characterized by increased branching. Expression of rasBΔ113-135, a mutant transgene lacking the conserved rasB internal amino acid insertion, did not complement the deletion phenotype of delayed growth and germination rates and abnormal hyphal morphology. Virulence of the rasB deletion strain was diminished; mice infected with this strain exhibited ∼65% survival compared to ∼10% with wild-type and reconstituted strains. These data support the hypothesis that rasB homologs, which are highly conserved among fungi that undergo hyphal growth, control signaling modules important to the directional growth of fungal hyphae.

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