Journal Article

Auxin-Induced Elongation Growth and Expressions of Cell Wall-Bound Exo- and Endo-β-Glucanases in Barley Coleoptiles

Toshihisa Kotake, Naoki Nakagawa, Kazuyoshi Takeda and Naoki Sakurai

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 41, issue 11, pages 1272-1278
Published in print November 2000 | ISSN: 0032-0781
Published online November 2000 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcd056
Auxin-Induced Elongation Growth and Expressions of Cell Wall-Bound Exo- and Endo-β-Glucanases in Barley Coleoptiles

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When auxin stimulates rapid cell elongation growth of cereal coleoptiles, it causes a degradation of 1,3:1,4-β-glucan in hemicellulosic polysaccharides. We examined gene expressions of endo-1,3:1,4-β-glucanase (EI) and exo-β-glucanase (ExoII), of which optimum pH are about 5, and molecular distribution of hemicellulosic polysaccharides in barley (Hordeum vulgare L.) coleoptile segments treated with or without IAA. IAA (10–5 M) stimulated the gene expression of EI, while it did not affect that of ExoII. IAA induced gene expression of EI after 4 h and increased wall-bound glucanase activity after 8 h. The molecular weight distribution of hemicellulosic polysaccharides from coleoptile cell walls was shifted to lower molecular weight region by 2 h of IAA treatment. Fusicoccin (10–6 M) mimicked IAA-induced elongation growth and the decrease in molecular weight of hemicellulosic 1,3:1,4-β-glucan of coleoptiles in the first 4 h, but it did not promote elongation growth thereafter. These facts suggest that acidification of barley cell walls by IAA action enhances pre-existing cell wall-bound glucanase activity in the early first phase of IAA-induced growth and the late second phase involves the gene expression of EI by IAA.

Keywords: Key words: Acid growth — Barley (Hordeum vulgare) coleoptile — Fusicoccin — Glucanase — IAA.; Abbreviations: ExoII, an isozyme of barley exo-β-glucanase II; EI and EII, isozymes of barley endo-1,3:1,4-β-glucanase I and II, respectively; FC, fusicoccin.

Journal Article.  4159 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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