The impact of microfibril orientations on the biomechanics of plant cell walls and tissues: modelling and simulations

TL;DR

This study models how the orientation of cellulose microfibrils at the ends of plant cells influences their mechanical behavior, revealing that microfibril arrangement affects lateral expansion and response to forces.

Contribution

It introduces a numerical elasticity model considering microfibril orientations at cell ends, providing new insights into their biomechanical role in plant cell growth.

Findings

Microfibril orientation affects lateral cell expansion.

Microfibril arrangement influences response to directed forces.

Orientation at cell ends does not impact axial expansion.

Abstract

It is known that the orientation of cellulose microfibrils within plant cell walls has an important impact on the morphogenesis of plant cells and tissues. Viewing the shape of a plant cell as a square prism or cylinder with the axis aligning with the primary direction of expansion and growth, the orientation of the microfibrils within the cell wall on the sides of the cell is known. However, not much is known about their orientation at the ends of the cell. Here we investigate the impact of the orientation of cellulose microfibrils within a plant cell wall at the ends of the cell by solving the equations of linear elasticity numerically. Three different scenarios for the orientation of the microfibrils are considered. The macroscopic elastic properties of the cell wall are obtained using homogenization theory from the microscopic description of the elastic properties of the cell wall microfibrils and wall matrix. It is found that the orientation of the microfibrils in the upper and lower parts of cell walls do not affect the expansion of the cell in the direction of its axis but do affect its expansion in the lateral directions. The arrangement of the microfibrils in the upper and lower parts of cell walls is especially important in the case of directed forces acting on plant cell walls and tissues.