Abstract
Phytohormones regulate plant development via a poorly understood signal response network. Here, we show that the phytohormone ethylene regulates plant development at least in part via alteration of the properties of DELLA protein nuclear growth repressors, a family of proteins first identified as gibberellin (GA) signaling components. This conclusion is based on the following experimental observations. First, ethylene inhibited Arabidopsis root growth in a DELLA-dependent manner. Second, ethylene delayed the GA-induced disappearance of the DELLA protein repressor of ga1-3 from root cell nuclei via a constitutive triple response-dependent signaling pathway. Third, the ethylene-promoted "apical hook" structure of etiolated seedling hypocotyls was dependent on the relief of DELLA-mediated growth restraint. Ethylene, auxin, and GA responses now can be attributed to effects on DELLA function, suggesting that DELLA plays a key integrative role in the phytohormone signal response network.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Arabidopsis / drug effects
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Arabidopsis / genetics
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Arabidopsis / growth & development*
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism*
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Ethylenes / pharmacology*
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Germination / physiology
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Gibberellins / pharmacology
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Green Fluorescent Proteins
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Indoleacetic Acids / pharmacology
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Luminescent Proteins / genetics
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Luminescent Proteins / metabolism
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Multigene Family
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Plant Growth Regulators / pharmacology
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Plant Proteins
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Plant Roots / drug effects
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Plant Roots / genetics
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Plant Roots / growth & development*
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Protein Kinases / genetics
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Protein Kinases / metabolism
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Seeds / physiology
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Signal Transduction / drug effects
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Signal Transduction / genetics
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Signal Transduction / physiology
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Transcription Factors / genetics
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Transcription Factors / metabolism*
Substances
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Arabidopsis Proteins
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Ethylenes
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GAI protein, Arabidopsis
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Gibberellins
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Indoleacetic Acids
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Luminescent Proteins
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Plant Growth Regulators
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Plant Proteins
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RGL1 protein, Arabidopsis
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RGL2 protein, Arabidopsis
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Recombinant Fusion Proteins
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Transcription Factors
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Green Fluorescent Proteins
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ethylene
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Protein Kinases
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CTR1 protein, Arabidopsis