Plant cell walls - mechanical and chemical modifications underpin growth and stress response

Abstract

Plant cell wall mechanics and its relationship to growth and environmental stress are not entirely revealed. By using atomic force microscopy stiffness tomography we monitored stiffness distribution in the cell wall layers and its evolution during growth phases of living single Arabidopsis cells. In the beginning and end of the cell growth, the average stiffness of the cell wall was low and the wall was mechanically homogenous, while in the exponential growth phase the average wall stiffness increased, with increasing heterogeneity and polysaccharide/lignin content shown by Fourier-transform infrared (FTIR) spectroscopy. In adult plants, we studied mechanical stimuli-induced compression/tension reaction in the tree stems, and thigmotropic twining of the vines. Confocal- and fluorescence detected linear dichroism (FDLD) microscopy revealed that in juvenile spruce stems under bending stress cell wall organisation changed. Our spectroscopic, FTIR- and FDLD microscopic studies of parenchima cell walls in Dioscorea vine stem mechanics showed that mechanical strain changes polysaccharid/lignin ratio and organisation,cellulose fibril order staying unchanged.