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

Abstract

Using cryo-electron tomography of vitrified sections of one month-old Arabidopsis thaliana inflorescence stem tissue, we visualized primary and secondary cell walls of xylem tissue. Extensive quantitative and statistical analysis of segmented 3D tomographic data allowed geometrically idealized 3D-CAD model building of prototypic microfibrils, cross-links, and their supramolecular microfibril 3D organization. We propose a prototypic microfibril model where a cellulose core is heavily decorated by a thin sheath of hemicellulose with infrequent but sturdy hemicellulose-based cross-links. Such prototypic microfibrils then adopt a rather unexpected 3D supramolecular organization of high order and complexity. We discuss a possible new role for lignin in plant cell walls at low concentrations with lignin not acting as a matrix but rather as a reinforcement of microfibrils and cross-links. Extensive computational simulations of mechanical properties further revealed that this 3D organization of the cell wall is not optimized for load bearing but instead for flexibility and ductility.\n\nOne Sentence SummaryCryo-electron tomography and mechanical simulations revealed cell wall 3D architecture, optimized for flexibility/ductility.