GIWAXS reveals interactions between cellulose and matrix polysaccharides in plant primary cell walls*

The spatial organization and interactions of the cell wall components determine growth, and physical and chemical properties of the cell wall. Elucidating the interactions between wall biopolymers is crucial for understanding how cell walls are assembled and for designing efficient approaches to digest cell walls for renewable energy and biomaterials. Here, we used grazing incidence wide angle X-ray scattering (GIWAXS) to investigate the effect of defective cell wall biosynthesis on the nanoscale organization of cellulose in primary cell walls. GIWAXS reveals that cellulose crystals have a preferred alignment in primary cell walls.  X-ray pole figures constructed using GIWAXS were used to quantify the degree of preferred orientation (texture) of cellulose crystals. Comparing pole figures from pectin and xyloglucan deficient mutants to that of wild type Arabidopsis thaliana reveals that cellulose texture is disrupted in pectin mutants, but not in xyloglucan mutants. Our results indicate that an absence of normal pectin during cell wall biosynthesis alters cellulose patterning in plant cell walls.