Inhibition of the Coleoptile Growth in Avena sativa by Endosperm Removal : Changes in Auxin, Osmotica and Cell Wall

概要

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Removal of the endosperm from 84-h-old etiolated oat seedlings strongly retarded the subsequent growth of coleoptiles. The contribution of the endosperm to coleoptile growth was studied. Endosperm removal was found to: (1) decrease the endogenous level of indole-3-acetic acid (IAA) in the coleoptile tip. IAA applied to the coleoptile tip stimulated coleoptile growth in seedlings with and without the endosperm. The sensitivity of the coleoptile to a suboptimal concentration of IAA was higher in seedlings without the endosperm than in intact ones. At the optimal concentration of IAA, however, the final length of the coleoptile was larger in intact seedlings than in those without the endosperm. (2) decrease the concentration of the soluble sugars and amino acids in the cell sap: (3) retard the increase in the amount of polysaccharides in the cell wall of the coleoptile, particularly noncellulosic ones. (4) make the cell wall mechanically rigid according to stress-relaxation analysis of the cell wall. (5) induce an increase in the osmotic potential of the coleoptile cell sap. From these results, it was concluded that the endosperm supplies the coleoptile with IAA, sugars and amino acids, thus promoting coleoptile growth.
日本植物生理学会の論文