The differences in the lignification of earlywood and latewood in larch (Larix sibirica Ldb.)
2007
Antonova, G.F.(V.N. Sukachev Inst. of Forests, Krasnoyarsk (Russian F.)) | Varaksina, T.N. | Stasova, V.V.
The rate of lignin deposition, its content and composition, and molecular weight distribution at different stages of secondary wall thickening during tracheid development of both earlywood and latewood in Siberian larch (Larix sibirica Ldb.) were studied in the stems of 25-year-old trees. The cells of early and late xylem at different stages of secondary wall development were obtained in late June and early in August, respectively. Lignification of the two types of wood was found to involve different dynamics. The intensity of lignin synthesis during earlywood formation increases gradually, reaching the maximum at the last stage of tracheid maturation. In contrast, lignin deposition in the course of latewood development is the highest only in the first stage of lignification and declines by the end of tracheid maturation. There were differences in the composition of alkaline oxidation products of lignin preparations at different developmental stages of early and late xylem. The contents of carbohydrates linked to lignin by ether and ester bonds were the highest in the first stage of lignification and greater in lignifying latewood than in earlywood. Lignins formed at the beginning of lignification of both wood types had higher molecular weights and were more homogeneous than those at the last stage of cell differentiation. The amount of cell wall substances deposited before lignification in earlywood is larger than that in latewood.
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