Journal Article

Involvement of Cortical Microtubules in Plastic Extension Regulated by Gibberellin in <i>Lemna</i> <i>minor</i> Root

Sayaka Inada and Teruo Shimmen

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 42, issue 4, pages 395-403
Published in print April 2001 | ISSN: 0032-0781
Published online April 2001 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pce049
Involvement of Cortical Microtubules in Plastic Extension
Regulated by Gibberellin in Lemna minor
Root

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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We aimed to analyze the rheological characteristics during elongation of the root segments in Lemna minor. The elastic component of segment elongation (EC) increased for the first 6 h, and then almost stopped. However, the plastic component of the segment elongation (PC) began to rapidly increase from 6 h onwards. Uniconazole-P, a gibberellin biosynthesis inhibitor, inhibited the total elongation of root segments (TE), and this inhibition was mainly caused by suppression of the rapid increase in the PC after 6 h. Concomitant with this inhibition, the cortical microtubule (CMT) array within root epidermal cells became disorganized in the presence of uniconazole-P from 6 h onwards. Adding GA3 abolished the inhibition of TE by uniconazole-P treatment, and this recovery was caused not by the increase in the EC but by an increase in the PC. Furthermore, the CMT arrays also recovered their characteristic organization in the presence of GA3. These findings suggest that endogenous gibberellin accelerates TE by activating the PC via control of CMT arrays. This conclusion is also supported by rheological analysis where propyzamide was used to disrupt microtubules. We suggest that endogenous gibberellin controls the PC via its influence over the transverse arrangement of CMTs.

Keywords: Key words: Cortical microtubule — Gibberellin — Lemna minor — Propyzamide — Root elongation — Uniconazole-P.; Abbreviations: CMT, cortical microtubule; DMSO, dimethylsulfoxide; EC, elastic component of segment elongation; EC/TE, ratio of the elastic component to total segment elongation; EGTA, ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid; PBS, phosphate-buffered saline; PC, plastic component of segment elongation; PC/TE, ratio of the plastic component to total segment elongation; PIPES, piperazine-N,N′-bis(2-ethanesulfonic acid); TE, total segment elongation; Un-P, uniconazole-P.

Journal Article.  5103 words.  Illustrated.

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

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