Polymer nanoscale morphology in Chara australis Brown cell walls studied by advanced solid state techniques

The cell wall of the green algae Chara australis Brown (Charophyta, Algae) has been examined with solid state techniques (suitable for characterising the nanoscale arrangement of polymers) and solid state chemistry. The chemical composition of a bulk dried sample of Chara australis was examined using cross-polarisation magic angle spinning (CP-MAS) ¹³C nuclear magnetic resonance (NMR). The presence of phenyl-propane subunits typical of the cross linked polymer, lignin, is not revealed. The arrangement of cellulose in the cell wall was probed by examining the wide angle diffraction pattern of a single fibre oriented with respect to an x-ray beam. The pattern produced was typical of a textured crystalline lattice embedded in an amorphous matrix. The x-ray reflections are much broader than most found in higher plants and it is difficult to resolve texture. Polarised Raman scattering from a similar sample provided clearer evidence of a textured cellulose matrix embedded in an amorphous matrix. It is found that the charophyte cell wall has many similarities in chemical composition and nanoscale arrangement of cell wall polymers to that of the higher plant, including the presence and arrangement, of cellulose and various polysaccharides.