Elevated levels of tubulin transcripts accompany the GA3-induced elongation of oat internode segments

Nandini Mendu, Carolyn D. Silflow

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Plant cell elongation involves the deposition of nascent cellulose microfibrils, the orientation of which is regulated in part by the cortical microtubule array. To determine whether changes in tubulin gene expression are associated with cell elongation, we examined GA3-elicited growth of excised internode segments of Avena sativa. Internode elongation was barely detectable after 6 h of GA3 treatment, when levels of beta-tubulin transcripts had increased 5-6 fold over levels found in untreated controls. Elongation continued for 48 h, whereas tubulin transcript levels reached a peak at 24 h and then declined. The extent of internode elongation and the level of tubulin transcript accumulation were dependent upon both concentration and duration of GA3 treatment. Although a 1 h pulse of GA3 treatment was sufficient to induce elongation and enhance tubulin transcript levels, constant GA3 application was necessary to elicit the maximum growth and transcript accumulation responses. Inhibition of internode elongation by abscisic acid and 2,6,dichlorobenzonitrile (an inhibitor of cellulose biosynthesis) or cycloheximide inhibited the GA3-mediated growth response and the accompanying elevation of tubulin transcript levels. The strong correlation we observed between internode elongation and tubulin transcript level suggests that tubulin gene expression is regulated in close association with cell elongation.

Original languageEnglish (US)
Pages (from-to)973-983
Number of pages11
JournalPlant and Cell Physiology
Issue number7
StatePublished - Oct 1993

Bibliographical note

Funding Information:
Immobilized by rigid walls, plant cells pattern their growth by controlling the planes of cell division and cell enlargement. Regulation of the plane of cell division determines the position and size of the nascent cell. However, the generation of the plant form is also dependent on the direction and extent of subsequent cell elongation. The orientation in which microfibrils are deposited determines the subsequent direction of cell expansion. Random deposition of cellulose microfibrils results in isodiametric cell growth while transverse or circumferential deposition of cell wall microfibres results in directional cell elongation and in an inhibition of lateral cell expansion (Hardham 1982). The regulation of the orientation of cellulose microfibril deposi- Abbreviations: DCB, 2,6,dichlorobenzonitrile; HS, Hoagland's solution. 1 Present address: Department of Genetics, North Carolina State University, Raleigh, NC 27695-7614, U.S.A. Financial support for this work was provided by the Quaker Oats Company.


  • Avena sativa
  • Cell elongation
  • Gene expression
  • Microtubules
  • Transcript levels
  • Tubulin


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