Journal Article

Changes in the Activities and Polypeptide Levels of Exo- and Endoglucanases in Cell Walls during Developmental Growth of <i>Zea mays</i> Coleoptiles

Masahiro Inouhe and Donald J. Nevins

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 39, issue 7, pages 762-768
Published in print July 1998 | ISSN: 0032-0781
Published online July 1998 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/oxfordjournals.pcp.a029432
Changes in the Activities and Polypeptide Levels of Exo- and Endoglucanases in Cell Walls during Developmental Growth of Zea mays Coleoptiles

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Exo- and endoglucanases present in cereal coleoptile cell walls are capable of mediating hydrolysis of non-cellulosic rβ-(l,3)(l,4)-glucan in situ. To assess the relationship with cell elongation, glucanase activities and the respective polypeptide abundance were determined as a function of Zea mays coleoptile development. Both exo- and endoglucanase activities were quite low initially, but increased to achieve maximum levels by days 5 or 6. Western blots revealed that the density of the protein bands increased with coleoptile development generally in correspondence to activity levels. However, in bioassays with 3 d old coleoptile segments we found that auxin stimulation of glucanase activities did not result from increased glucanase polypeptide levels. Hence, there was no evidence for de novo protein synthesis in excised coleoptiles in response to added auxin. While glucanase antibodies strongly inhibited IAA-induced elongation of coleoptile segments on days 2–4, these same antibodies had little effect on day 1. We conclude that glucanases contribute to auxin mediated coleoptile growth only during a limited developmental interval. We propose that when elongation is dominate, the physical properties of the cell wall adjust in response to metabolism of cell wall rβ-(l,3)(l,4)-glucans but the enhancement of such activity is governed by factors other than glucanase protein levels.

Keywords: Antibodies; Auxin; Cell elongation; Cell wall; Glucan; Glucanases

Journal Article.  0 words. 

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

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