Studies on the specificity of interaction of cereal cell wall components with Congo Red and Calcofluor. Specific detection and histochemistry of (1→3),(1→4),-β-D-glucan

The (1→3),(1→4)-β-D-glucan of oats (Avena sativa) induces major changes in the absorption and fluorescence spectra of the dyes Congo Red and Calcofluor, and is stained intensely by these dyes. The interactions are not observed following degradation of the polysaccharide by a specific β-D-glucan endohydrolase from Bacillus subtilis (EC. 3.2.1.73). Spectral changes in the dyes, and staining as assessed by fluorescence microscopy, were observed with various cell wall preparations and polysaccharide fractions from oats, barley (Hordeum vulgare) and wheat (Triticum aestivum), but were abolished following treatment with the β-D-glucan endohydrolase, thereby establishing the specificity of the dye binding. Components other than (1→3),(1→4)-β-D-gslucan, such as arabinoxylan, nelther stained nor showed interaction in solution. The specificity of the dye-polysaccharide interaction enabled the location of (1→3),(1→4)-β-D-glucan to be identified as being in the endosperm cell walls and inner walls of aleurone cells in oats, barley and wheat.