Toward identifying molecules responsible for the peculiar properties of the G-layer in tension wood fibres
© Guedes et al; licensee BioMed Central Ltd. 2011
Published: 13 September 2011
Due to its peculiar properties, tension wood formation constitutes a remarkable adaptation mechanism, that makes possible for the tree to reorientate its axes (stem and branches) in response to environnemental cues. In poplar, tension wood fibres harbour an extra cell wall layer, the G-layer, responsible for the peculiar mechanical properties of tension wood. This G-layer is very thick, most likely devoid of lignins and strongly enriched in highly cristalline cellulose. In addition, cellulose microfibril orientation is almost parallel to the fibre axis.
We aim to identify molecular actors responsible for the tensioning of cellulose microfibrils and we choose as candidate, molecules containing complex carbohydrates, such as pectin and the glycosylated part of arabinogalactan proteins. Indeed, a wide array of different carbohydrates has been recently evidenced in the G-layer, suggesting the occurrence of complex polysaccharides other than cellulose within this layer (1, 2).
Material and methods
As a first step, we realized a comparative study between tension and opposite wood fibres using immunochemistry. A number of antibodies raised against different polysaccharide epitopes were assessed.
Our results strongly suggest the involvement of pectin and arabinogalactan proteins in the building of the G-layer.
The PhD thesis of Fernanda TP Guedes is funded by Coordenação de Aperfeiçoamento de Pessoal de Nivel Superior – CAPES.
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