Acid- and Enzyme-Mediated Solubilization of Cell-Wall beta-1.3,beta-1.4-d-Glucan in Maize Coleoptiles : Implications for Auxin-Mediated Growth.
The release of soluble carbohydrates from isolated cell wall of maize (Zea mays L.) was investigated in the range of pH 1 to 8.5. The pH profile demonstrated two peaks, a broad peak at pH 6 due to enzymatic breakdown of beta-glucan to monosaccharides (wall autolysis) and a sharp peak at pH 2.5 due to acid-mediated, nonenzymatic liberation of macromolecular beta-glucan from the wall. The pH dependence of acid-induced growth and cell-wall extensibility of coleoptile segments closely agrees with the pH dependence of acid-mediated beta-glucan solubilization in the isolated wall. However, there is no evidence that enzymatic or nonenzymatic beta-glucan solubilization is involved in the mechanism of auxin-mediated growth.
Hohl
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Biologisches Institut der Universität, Schänzlestrasse 1, D-7800 Freiburg, Federal Republic of Germany.
Hong
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Schopfer
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