Comparative studies on lignin structures in normal and tension wood of Populus x euramericana cv. 74/76

Tension wood is a type of defect of wood, however, it has some especial character and structure. In this study, cellulase lignin structures in normal and tension wood of Poplar 107 (Populus x euramericana cv. '74/76') were compared using ultraviolet (UV), Fourier transform infrared (FT-IR), Raman and magnetic resonance (NMR) sped, oscopy, gel permeation chromatography (GPC) and elemental analysis.The results showed that the lignins in both normal and tension wood were dominated by syringyl units, followed by guaiacyl and p-hydroxyphenyl units. The FT-IR result presented that the relative intensity of syringyl units in normal and tension wood were 0.87 and 0.90. The contents of aliphatic hydroxyl, met hoxyl, condensed phenolic hydroxyl and carboxyl of lignin in tension wood were higher than those of phenolic hydroxyl groups and beta-5. The contents of beta-O-4, beta-beta and beta-1 in tension wood were similar with those in normal wood. The average per-C-9-unit formulae of the lignin in normal and tension wood of Poplar 107 were C9H7.21O1.79(OH)(1.)(17)(_x)(0001)(_)(OCH3)(1.55) and C9H7.23O1.76(OH)(1).(25_x)(0001)(_)(OCH3)(1.)(62), respectively. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study compared the cellulase lignin structures in normal and tension wood of Poplar 107, and found that tension wood had higher lignin content. Both normal and tension wood were dominated by syringyl units, with tension wood showing higher content of certain elements compared to normal wood.