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The length of the Arabidopsis thaliana life cycle depends on the timing of the floral transition. Here, we define the relationship between the plant stress hormone ethylene and the timing of floral initiation. Ethylene signaling is activated by diverse environmental stresses, but it was not previously clear how ethylene regulates flowering. First, we show that ethylene delays flowering in Arabidopsis, and that this delay is partly rescued by loss-of-function mutations in genes encoding the DELLAs, a family of nuclear gibberellin (GA)-regulated growth-repressing proteins. This finding suggests that ethylene may act in part by modulating DELLA activity. We also show that activated ethylene signaling reduces bioactive GA levels, thus enhancing the accumulation of DELLAs. Next, we show that ethylene acts on DELLAs via the CTR1-dependent ethylene response pathway, most likely downstream of the transcriptional regulator EIN3. Ethylene-enhanced DELLA accumulation in turn delays flowering via repression of the floral meristem-identity genes LEAFY (LFY) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1). Our findings establish a link between the CTR1/EIN3-dependent ethylene and GA-DELLA signaling pathways that enables adaptively significant regulation of plant life cycle progression in response to environmental adversity.

Original publication

DOI

10.1073/pnas.0610717104

Type

Journal article

Journal

Proc Natl Acad Sci U S A

Publication Date

10/04/2007

Volume

104

Pages

6484 - 6489

Keywords

Arabidopsis, Arabidopsis Proteins, Ethylenes, Flowers, Gene Expression Regulation, Plant, Gibberellins, Immunoblotting, MADS Domain Proteins, Mutation, Nuclear Proteins, Plant Growth Regulators, Repressor Proteins, Reverse Transcriptase Polymerase Chain Reaction, Signal Transduction, Transcription Factors