(240i) Mechano-Chemical Analyses of Plant Cell Walls at Nanoscale Using Atomic Force Microscopy Coupled with Infrared Spectroscopy

Plant cell walls play a critical role in protecting against environmental stress, providing structural support, and determining the rate and direction of cell growth. The organization of plant cell wall components plays a role in determining the local mechanical properties of the cell wall. As a result, the natural processes of plant cell and tissue growth, development, and function rely on control of cell wall composition, arrangement, and ultrastructure to manipulate local mechanical properties. Investigating the role of local chemical composition on the local mechanical properties of the plant cell wall requires that methodologies probing the cell wall chemical and mechanical properties be at a length scale smaller than the size of the plant cell. In this study, methods of atomic force microscopy coupled with Infrared spectroscopy (AFM-IR) was developed to perform nanoscale multimodal imaging of the physical, chemical, and mechanical features of plant cell walls in the Arabidopsis stems and roots, and poplar tension wood. AFM-IR not only overcomes the diffraction resolution limit of other chemical imaging techniques like IR microspectroscopy, but also characterizes mechanical and chemical properties of the samples simultaneously at nanoscale. Using multivariate statistical analysis tools, we were able to quantify compositional variations and mechanical heterogeneity, and to correlate the chemical composition and local mechanical properties in Arabidopsis and poplar cell walls.