Exploring the micromechanical design of plant cell walls.

Plants are hierarchically organized in a way that their macroscopic properties emerge from their micro- and nanostructural level. Hence, micromechanical investigations, which focus on the mechanical design of plant cell walls, are well suited for elucidating the details of the relationship between plant form and function. However, due to the complex nature of primary and secondary cell walls, micromechanical tests on the entire structure cannot provide exact values for polymer properties but must be targeted at the general mechanisms of cell wall deformation and polymer interaction. The success of micromechanical examinations depends on well-considered specimen selection and/or sample pretreatment as well as appropriate experimental setups. Making use of structural differences by taking advantage of the natural variability in plant tissue and cell structure, adaptation strategies can be analyzed at the micro- and nanoscale. Targeted genetic and enzymatic treatments can be utilized to specifically modify individual polymers without degrading the structural integrity of the cell wall. The mechanical properties of such artificial systems reveal the functional roles of individual polymers for a better understanding of the mechanical interactions within the cell wall assembly. In terms of testing methodology, in situ methods that combine micromechanical testing with structural and chemical analyses are particularly well suited for the study of the basic structure-property relationships in plant design. The micromechanical approaches reviewed here are not exhaustive, but they do provide a reasonably comprehensive overview of the methodology with which the general mechanisms underlying the functionality of plant micro- and nanostructure can be explored without destroying the entire cell wall.