Modelling the mechanical properties of xylem tissue from tobacco plants (Nicotiana tabacum 'Samsun') by considering the importance of molecular and micromechanisms

Abstract

Tobacco plants (Nicotiana tabacum 'Samsun') have xylem cell walls which are more sensitive to changes in the properties of the matrix than was predicted using current cell wall mechanical models. A model is proposed which can account for the importance of the cell wall matrix in determining the modulus of the material. This model is based on a helical spring system, with micromechanisms operating at the molecular scale. Xylem tissue fibre cells can behave as helical springs when the crosslink density of lignin is low, or they can behave like a composite sheet with fibres at an angle to the applied load when the crosslink density is high. This highlights the importance of molecular modelling when the properties of complex biological materials are being investigated.