Organization of the Plant Cell Wall

Sarkar, Purnamrita; Auer, Manfred

doi:10.1201/b20316-10

Cited by 1 publication

(1 citation statement)

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“…The minus/plus/minus 27° deviation from an axial orientation caused a dramatic stiffness drop in the axial direction, but also a 200-fold increase in the elastic strain energy density. Without transition zones (18 layers that are minus/plus/minus 27° inclined, Fig. S3B), axial stiffness was further reduced by a factor of 4, with an increased elastic energy storage of 30%, whereas if all microfibrils (54 layers) were inclined by 27° (Fig.…”

Section: Mechanical Cell Wall Propertiesmentioning

confidence: 99%

Cryo-Electron tomography 3D structure and nanoscale model of Arabidopsis thaliana cell wall

Sarkar

et al. 2018

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23Using cryo-electron tomography of vitrified sections of one month-old Arabidopsis thaliana 24 inflorescence stem tissue, we visualized primary and secondary cell walls of xylem tissue. 25Extensive quantitative and statistical analysis of segmented 3D tomographic data allowed 26 geometrically idealized 3D-CAD model building of prototypic microfibrils, cross-links, and their 27 supramolecular microfibril 3D organization. We propose a prototypic microfibril model where a 28 cellulose core is heavily decorated by a thin sheath of hemicellulose with infrequent but sturdy 29 hemicellulose-based cross-links. Such prototypic microfibrils then adopt a rather unexpected 3D 30 supramolecular organization of high order and complexity. We discuss a possible new role for 31 lignin in plant cell walls at low concentrations with lignin not acting as a matrix but rather as a 32 reinforcement of microfibrils and cross-links. Extensive computational simulations of 33 mechanical properties further revealed that this 3D organization of the cell wall is not optimized 34 for load bearing but instead for flexibility and ductility. 35 36 One Sentence Summary: 37 Cryo-electron tomography and mechanical simulations revealed cell wall 3D architecture, 38 optimized for flexibility/ductility. 39 40 3 Cell walls provide mechanical strength and protection to plants, while being flexible to 41 support their growth and development and have been studied for over eight decades (1-6). The 42 current model of plant cell walls portrays a framework of ~3.5 nm thick cellulose microfibrils, 43interconnected by single-strand hemicellulose thus forming a rather loose 3D "long-tether" 44 network, with hemicellulose adhering to significant stretches of the microfibrils (7-14). Other 45 prominent cell wall components, pectins are predominantly found in the middle lamella (ML) 46 adhering two adjacent cells (15), whereas phenolic lignin polymers are thought to form a 47 hydrophobic matrix in between the cellulose-hemicellulose network (15, 16). The most 48 commonly discussed cell wall model has microfibrils alternating between two sharply distinct 49 orientations, not unlike textile fabric (3, 7, 11), however alternative models have been proposed 50 (1)(2)(17)(18)(19). 51Numerical simulation of mechanical properties using approximation techniques such as 52 the finite element method (20) require realistic 3D cell wall structures and models, and to date 53 have been based on the assumption of pseudo-random fiber networks (21-23). Model building 54 allows virtual testing of the different cell wall components and alternative 3D configurations. As 55 for fiber-reinforced composites, homogenization techniques can be combined with finite element 56 methods to extract global properties such as stiffness of the wall. 57Here we used cryo-electron tomography vitreous sections of 1-month old Arabidopsis 58 thaliana inflorescence stems (24) to reveal the 3D nano-architecture of microfibrils and their 59 cross-connectors, as well as the supramolecular 3D organization of ...

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Section: Mechanical Cell Wall Propertiesmentioning

confidence: 99%