Immunolocalization of (1,4)-β-galactan in tension wood fibers of poplar
Matthias Arend (1)
1. Technische Universität München, Fachgebiet Angewandte Holzbiologie, Winzererstrasse 45, 80797 München, Germany () / Received January 2, 2008; accepted March 14, 2008; published online June 2, 2008
Summary
The occurrence and distribution of (1,4)-β-galactan in wood cells of poplar (Populus trichocarpa Torr. & A. Gray × P. koreana Rehder) were studied by immunolabeling with a monoclonal antibody (LM5) specific to this carbohydrate epitope. Immunofluorescence
microscopy revealed exclusive binding of the LM5 antibody to tension wood fibers, indicating the specific presence of (1,4)-β-galactan
in cell walls of this wood cell type. Higher magnifications achieved with the fluorescence microscope and additional immunogold
electron microscopy showed that the binding of the LM5 antibody was mainly restricted to a narrow cell wall area between the
gelatinous G-layer and the secondary cell wall. This labeling pattern strongly suggests a role of (1,4)-β-galactan in cross-linking
the G-layer and secondary cell wall. Furthermore, the exclusive localization of (1,4)-β-galactan in tension wood strengthens
the view that this carbohydrate epitope can be considered a highly specific marker of reaction wood formation in mechanically
stressed trees.
