Characterization of cellulose microfibril crystal orientation in primary cell walls using X-ray scattering

Cellulose, one of the key components in plant cell walls, holds promise as a renewable source for biofuel production. In plant cell walls, cellulose is assembled into fibrils that are 3-5 nm in diameter and several hundred microns long. These cellulose microfibrils are stiff and are the load bearing component in plant cell walls. Nevertheless, many aspects of cellulose microfibril organization remain unknown, such as the orientation of cellulose crystals within fibrils. We have used grazing-incidence wide angle X-ray scattering to measure the distribution of cellulose crystal orientations with respect to the plant cell wall. Taking advantage of the high-flux X-ray source at synchrotron facilities and grazing incidence geometry, we generated pole figures to systematically study a series of primary cell walls. Samples were treated with different chemicals and enzymes to remove various components of the cell wall. Our results demonstrate that crystals within cellulose microfibrils in the plant cell wall have a preferred orientation, and that the degree of orientational order (texturing) varies depending on the plant species and type of tissue in a way not currently possible to reveal with other techniques.