Use of lectin to detect the sugar components of maize root cap slime.

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Abstract
The main sugars known to be present in maize [Zea mays cv. Caldera] root cap slime (fucose, galactose, glucose) were detected by the use of various lectins. The detection of sugars present in the slime was conducted by experiments of inhibition of [rabbit and human] red blood cell agglutination and by labeling with fluoresceinyl derivatives of lectins (Flu-lectins). The slime could not be used as an inhibitor of red blood cell agglutination because the red blood cells were untrapped in the undisrupted slime and could not sediment. The sedimentation of red blood cells in the presence of sonicated slime was not impaired. Sonicated slime specifically inhibited the agglutination induced by the following lectins: fucose binding proteins (LtA from Lotus tetragonolobus and UeA from Ulex europaeus), glucose (or mannose) binding protein (Concanavalin A from Canavalia ensiformis), galactose binding lectin (PNA from Arachis hypogaea). The minimal concentrations of sonicated slime required to give a total inhibition were 0.7 .mu.g/ml, 25 .mu.g/ml, respectively. The red blood cell agglutination induced by a N-acetyl glucosamine binding lectin (WGA from Triticum vulgare) was not inhibited by the sonicated slime. The agglutination activity of the lectins which bind sugars known to be present in the slime was inhibited by the sonicated slime. Flu-UeA and Flu-LtA band strongly root cap cells and the secreted slime; Flu-Con A gave only a weak labeling. Flu-PNA, of which the agglutination activity is very easily inhibited by sonicated slime, did not give any labeling at the root cap level. Flu-WGA, of which the agglutination activity was not inhibited by the sonicated slime, did not give any labeling. The sugar binding specificity of the lectins and of the lectin accessibility of sugars in the slime are discussed. Possibly fucose is fully accessible in both sonicated and unsonicated slime while galactose is not accessible in unsonicated slime. Fucose binding lectins, amongst all the test lectins, may be the best tools to investigate the biosynthesis of maize slime.