Quantitative analysis for the cellulose Iα crystalline phase in developing wood cell walls

FT-IR and X-ray analyses were employed to determine the relative ratio of cellulose I(α) and I(β) crystalline phases present in each developmental stage of coniferous tracheid cell wall formation. The IR spectra showed that initially the I(α) phase occupies 50% of the crystalline regions in the primary cell wall cellulose and this value drops to 20% after ceasing of the cell enlarging growth for the formation of the secondary wall cellulose (the remaining regions are composed of the I(β) phase). Although it is reasonable that the content for I(β), which is stress-reduced crystalline form, was higher in the secondary wall formation (Kataoka Y, and Kondo T. Macromolecules 1996;29:6356-6358) it is more interesting that during the crystallization of stress-induced I(α) cellulose for the primary wall the stress-reduced I(β) is also possible to be crystallized in an alternative way. This means that throughout the period the I(α)-causing stress may not be necessarily kept loaded. In light of our previously reported hypothesis (Kataoka Y. and Kondo T. Macromolecules 1998;31:760-764) for the formation of I(α) phase due to cellular growing stresses in the primary wall cellulose, such an alternating on-off stress effect to account for the occurrence of both I(α) and I(β) phases might be related to a biological growth system in coniferous wood cells.