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-alpha and I-beta crystalline phases present in each developmental stage of coniferous tracheid cell wall formation. The IR spectra showed that initially the I-alpha 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-beta phase). Although it is reasonable that the content for I-beta, 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-beta cellulose for the primary wall the stress-reduced I-beta is also possible to be crystallized in an alternative way. This means that throughout the period the I-alpha-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-alpha 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-alpha and I-beta phases might be related to a biological growth system in coniferous wood cells. (C) 1999 Elsevier Science B.V. All rights reserved.