Ultrastructure of the innermost surface of differentiating normal and compression wood tracheids as revealed by field emission scanning electron microscopy

Abstract

The ultrastructure of the innermost surface of Cryptomeria japonica differentiating normal wood (NW) and compression wood (CW) was comparatively investigated by field emission electron microscopy (FE-SEM) combined with enzymatic degradation of hemicelluloses. Cellulose microfibril (CMF) bundles were readily observed in NW tracheids in the early stage of secondary cell wall formation, but not in CW tracheids because of the heavy accumulation of amorphous materials composed mainly of galactans and lignin. This result suggests that the ultrastructural deposition of cell wall components in the tracheid cell wall differ between NW and CW from the early stage of secondary cell wall formation. Delignified NW and CW tracheids showed similar structural changes during differentiating stages after xylanase or beta-mannanase treatment, whereas they exhibited clear differences in ultrastructure in mature stages. Although thin CMF bundles were exposed in both delignified mature NW and CW tracheids by xylanase treatment, ultrastructural changes following beta-mannanase treatment were only observed in CW tracheids. CW tracheids also showed different degradation patterns between xylanase and beta-mannanase. CMF bundles showed a smooth surface in delignified mature CW tracheids treated with xylanase, whereas they had an uneven surface in delignified mature CW tracheids treated with beta-mannanase, indicating that the uneven surface of CMF bundles was related to xylans. The present results suggest that ultrastructural deposition and organization of lignin and hemicelluloses in CW tracheids may differ from those of NW tracheids.

Keywords

Cellulose microfibril; Compression wood; Cryptomeria japonica; FE-SEM; Hemicellulose; Lignin

Published in

Planta
2012, volume: 235, number: 6, pages: 1209-1219
Publisher: SPRINGER

SLU Authors

• Kim, Jongsik

  • Department of Forest Products, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Biochemistry
Wood Science
Molecular Biology

Publication identifier

• DOI: https://doi.org/10.1007/s00425-011-1569-7

Permanent link to this page (URI)

https://res.slu.se/id/publ/45522