Transient gibberellin application promotes Arabidopsis thaliana hypocotyl cell elongation without maintaining transverse orientation of microtubules on the outer tangential wall of epidermal cells
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ArticleKAUST Grant Number
KUK-I1-002-03Date
2011-11-25Online Publication Date
2011-11-25Print Publication Date
2012-02Permanent link to this record
http://hdl.handle.net/10754/600061
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The phytohormone gibberellin (GA) promotes plant growth by stimulating cellular expansion. Whilst it is known that GA acts by opposing the growth-repressing effects of DELLA proteins, it is not known how these events promote cellular expansion. Here we present a time-lapse analysis of the effects of a single pulse of GA on the growth of Arabidopsis hypocotyls. Our analyses permit kinetic resolution of the transient growth effects of GA on expanding cells. We show that pulsed application of GA to the relatively slowly growing cells of the unexpanded light-grown Arabidopsis hypocotyl results in a transient burst of anisotropic cellular growth. This burst, and the subsequent restoration of initial cellular elongation rates, occurred respectively following the degradation and subsequent reappearance of a GFP-tagged DELLA (GFP-RGA). In addition, we used a GFP-tagged α-tubulin 6 (GFP-TUA6) to visualise the behaviour of microtubules (MTs) on the outer tangential wall (OTW) of epidermal cells. In contrast to some current hypotheses concerning the effect of GA on MTs, we show that the GA-induced boost of hypocotyl cell elongation rate is not dependent upon the maintenance of transverse orientation of the OTW MTs. This confirms that transverse alignment of outer face MTs is not necessary to maintain rapid elongation rates of light-grown hypocotyls. Together with future studies on MT dynamics in other faces of epidermal cells and in cells deeper within the hypocotyl, our observations advance understanding of the mechanisms by which GA promotes plant cell and organ growth. © 2011 Blackwell Publishing Ltd.Citation
Sauret-Güeto S, Calder G, Harberd NP (2011) Transient gibberellin application promotes Arabidopsis thaliana hypocotyl cell elongation without maintaining transverse orientation of microtubules on the outer tangential wall of epidermal cells. The Plant Journal 69: 628–639. Available: http://dx.doi.org/10.1111/j.1365-313X.2011.04817.x.Sponsors
We thank Chris Hindle and John Humble from the workshop at the John Innes Centre for building the growth tracking chamber. We thank Enrico Coen for useful discussions on growth. We thank Jinrong Peng for provision of the ga1-3 (Col-0) line. We thank Jordi Chan for provision of the P35S:GFP-TUA6 line and for interesting discussions. We thank Paul Southam for help with IMAGEJ. We thank Rene Dreos for help with statistics. This work was funded by the Biotechnology and Biological Sciences Research Council (Core Strategic Grant to the John Innes Centre and Response Modes Grant BB/D521665/1) and by a Beatriu de Pinos post-doctoral fellowship from the Generalitat de Catalunya (2005 BP-A 10110) to SSG. This work was supported in part by award no. KUK-I1-002-03 (to NPH) made by King Abdullah University of Science and Technology (KAUST).Publisher
WileyJournal
The Plant JournalPubMed ID
21985616ae974a485f413a2113503eed53cd6c53
10.1111/j.1365-313X.2011.04817.x
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