Immunolocalisation of galactan in compression wood of Pinus radiata

Hamburg

2007

S. 105-110

7 Abb., 12 Lit. Ang.

Artikel aus einer ZeitschriftUnselbständiges Werk

200151616

Galactan was localised in Pinus radiata compression wood cells by confocal microscopy using immunofluorescence and by transmission electron microscopy (TEM) using immunogold cytochemistry. The compression wood containing regions of sections were readily identified by confocal microscopy because of a strong lignin autofluorescence of their cell wall, reflecting a high lignin content. The pattern of immunofluorescence localisation of galactan closely corresponded to the pattern of lignin autofluorescence, with the compression wood regions being brightly fluorescent for galactan and the normal wood regions showing only a weak fluorescence. Higher magnifications, which more clearly resolved the patterns of cell wall autofluorescence and galactan immunofluorescence, showed the outer S2 region of compression wood cell wall to display brightest autofluorescence, indicating this cell wall to be most highly lignified, and immunofluorescence for galactan to be strongest in this region. High magnification confocal imaging also indicated that while the compound middle lamella region of compression wood was also autofluorescent, this region lacked fluorescence for galactan. The higher resolution of TEM, combined with the use of gold-conjugated secondary antibody, confirmed the results obtained by confocal microscopy, as well as showing that gold particles were confined to the cell wall regions corresponding to S1 and outer S2 layers. Gold particles were not found in other regions of compression wood cell wall. The observed specific cell wall localisation of galactan suggests that galactan may have a role in the development and function of compression wood cells by modeling cell wall nano-architecture for specific functions.