Macromolecular biophysics of the plant cell wall: Concepts and methodology

Plant cell walls provide form and mechanical strength to the living plant, but the relationship between their complex architecture and their remarkabl e ability to withstand external stress is not well understood. Primary cell wails are adapted to withstand tensile stresses while secondary cell walls also need to withstand compressive stresses. Therefore while primary cell walls can with advantage be flexible and elastic, secondary cell walls must be rigid to avoid buckling under compressive loads. In addition, primary c ell walls must be capable of growth and are subjected to cell separation fo rces at the cell corners. To understand how these stresses are resisted by cell walls, it will be necessary to find out how the walls deform internall y under load, and how rigid are specific constituents of each type of cell wall. The most promising spectroscopic techniques for this purpose are soli d-stale nuclear magnetic resonance (NMR), and Fourier-transform infrared (F TIR) and Raman microscopy. By NMR relaxation experiments, it is possible to probe thermal motion in each cell-wall component. Novel adaptations of FTI R and Raman spectroscopy promise to allow mechanical stress and strain upon specific polymers to be examined in situ within the cell wall. (C) 2000 Ed itions scientifiques et medicares Elsevier SAS.