A role for gibberellic acid in orienting microtubules and regulating cell growth polarity in the maize root cortex |
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Authors: | F Balu?ka J S Parker P W Barlow |
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Institution: | (1) Department of Agricultural Sciences, University of Bristol, AFRC Institute of Arable Crops Research, Long Ashton Research Station, BS189AF Bristol, UK;(2) Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 14, 84223 Bratislava, Slovakia |
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Abstract: | The role of gibberellins and cortical microtubules in determining the polarity of cell growth in the root cortex of maize (Zea mays L.) was examined. Inhibition of gibberellin biosynthesis, either naturally through mutation (d5 mutant) or by means of chemicals such as 2S,3S paclobutrazol, caused thickening of root apices and increased their starch content. Immunofluorescence microscopy of cortical microtubules, coupled with a comparison of cell widhts, lengths and shapes, indicated that the meristem and immediate post-mitotic zone were the targets of gibberellin deficiency. Cortical cells in these regions were impaired in their ability to develop highly ordered transversal arrays of cortical microtubules. Consequently, the cells became wider and shorter. Application of gibberellic acid re-established the arrangements of cortical microtubules and the polarity of cell growth characteristic for roots having normal levels of gibberellins, it also decreased the starch content. These results indicate that gibberellins are morphogenetically active substances, not only in shoots but also in roots of maize.Abbreviations CMT
cortical microtubule
- GA
gibberellin
- GA3
gibberellic acid
- MT
microtubule
- PIG
postmitotic isodiametric growth
The authors acknowledge the support to F.B. from the Royal Society (London UK). We also thank Dr. J. Lenton (University of Bristol, Long Ashton Research Station) who kindly supplied us with 2S,3S paclobutrazol and grains of the GA-deficient d5 mutant of maize. |
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Keywords: | Cell (growth polarity shape) Gibberellin Growth polarity (root cortex) Microtubule Zea |
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