Journal Article

Ethylene-induced <i>Arabidopsis</i> hypocotyl elongation is dependent on but not mediated by gibberellins

Filip Vandenbussche, Bram Vancompernolle, Ivo Rieu, Margaret Ahmad, Andy Phillips, Thomas Moritz, Peter Hedden and Dominique Van Der Straeten

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 58, issue 15-16, pages 4269-4281
Published in print December 2007 | ISSN: 0022-0957
Published online December 2007 | e-ISSN: 1460-2431 | DOI: http://dx.doi.org/10.1093/jxb/erm288
Ethylene-induced Arabidopsis hypocotyl elongation is dependent on but not mediated by gibberellins

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Ethylene, or its precursor 1-aminocyclopropane-1-carboxylic acid (ACC), can stimulate hypocotyl elongation in the light. It is questioned whether gibberellins (GAs) play a role in this response. Tests with light of different wavelengths demonstrated that the ethylene response depends on blue light and functional cryptochrome signalling. Levels of bio-active GA4 were reduced in seedlings showing an ethylene response. Furthermore, ACC treatment of seedlings caused accumulation of the DELLA protein RGA, a repressor of growth. Concurrently, transcript levels of several GA biosynthesis genes were up-regulated and GA inactivation genes down-regulated by ACC. Hypocotyl elongation in response to ACC was strongly reduced in seedlings with a diminished GA signal, while being vigorously stimulated in a quadruple DELLA knock-out mutant with constitutive GA signalling. These data show that ethylene-driven hypocotyl elongation is mainly blue light-dependent and that this ethylene response, although GA dependent, hence needing a basal GA level, is not mediated by GA, but rather acts via a separate pathway.

Keywords: Arabidopsis; ethylene; gibberellin; hypocotyl elongation; light signalling

Journal Article.  7347 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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