Isolation, histochemistry and monosaccharide composition of the walls of root hairs from Heterozostera tasmanica (Martens ex Aschers.) den Hartog

Abstract

The walls of root hairs of the marine monocotyledon Heterozostera tasmanica (Martens ex Ashcers.) den Hartog were isolated after disruption of the root hairs by sonication. Histological examination using a range of stains indicated the presence of polyanionic molecules in the walls. After treatment with the detergent cetyltrimethylammonium bromide (CTAB), the staining with Alcian Blue was abolished. Protein staining was observed only after CTAB treatment. The root hairs stained with Auramine O before and after CTAB treatment suggesting the presence of lipid and/or cutin. Both Congo Red and Calcofluor White M2R induced intense ultraviolet fluorescence after detergent treatment, indicating the presence of β-glucans. Callose ((1→3)-β-glucan) deposits were revealed, after CTAB treatment, by the aniline blue fluorochrome. Carbohydrates constituted 83% (w/w) of the root hair wall. No lignin was detected, but a significant amount (17%, w/w) of the wall preparation was not recovered. The main monosaccharides present were apoise, 40 mol %, uronic acids 33 mol % and glucose, 10 mol %, together with smaller amounts of rhamnose, fucose, arabinose, xylose, mannose and galactose totalling 17 mol %. It is likely that the major wall polysaccharide is an apiogalacturonan and that most of the glucose arises from cellulose.