title: Convergence of auxin and gibberellin signaling on the regulation of the GATA transcription factors GNC and GNL in Arabidopsis thaliana.
abstract: Plant growth is regulated by a complex network of signaling events. Points of convergence for the signaling cross-talk between the phytohormones auxin and gibberellin (GA), which partly control overlapping processes during plant development, are largely unknown. At the cellular level, auxin responses are controlled by members of the AUXIN RESPONSE FACTOR (ARF) family of transcription factors as well as AUXIN/INDOLE-3-ACETIC ACID INDUCIBLE (AUX/IAA) proteins that repress the activity of at least a subset of ARFs. Here, we show that the two paralogous GATA transcription factors GATA, NITRATE-INDUCIBLE, CARBON-METABOLISM INVOLVED (GNC) and GNC-LIKE (GNL)/CYTOKININ-RESPONSIVE GATA FACTOR1 (CGA1) are direct and critical transcription targets downstream from ARF2 in the control of greening, flowering time, and senescence. Mutants deficient in the synthesis or signaling of the phytohormone GA are also impaired in greening, flowering, and senescence, and interestingly, GNC and GNL were previously identified as important transcription targets of the GA signaling pathway. In line with a critical regulatory role for GNC and GNL downstream from both auxin and GA signaling, we show here that the constitutive activation of GA signaling is sufficient to suppress arf2 mutant phenotypes through repression of GNC and GNL. In addition, we show that GA promotes ARF2 protein abundance through a translation-dependent mechanism that could serve to override the autoinhibitory negative feedback regulation of ARF2 on its own transcription and thereby further promote GA signaling.
authors.affiliation: Plant Systems Biology, Technische Universität München, 85354 Freising, Germany.
authors.forename: René
authors.initials: R
authors.lastname: Richter
authors.forename: Carina
authors.initials: C
authors.lastname: Behringer
authors.forename: Melina
authors.initials: M
authors.lastname: Zourelidou
authors.forename: Claus
authors.initials: C
authors.lastname: Schwechheimer
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005875:Gibberellins / Q000378:metabolism* / Q000494:pharmacology; D015151:Immunoblotting; D007210:Indoleacetic Acids / Q000378:metabolism* / Q000494:pharmacology; D008957:Models, Genetic; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology; D030821:Plants, Genetically Modified; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C503421:ARF2 protein, Arabidopsis; C503425:ARF7 protein, Arabidopsis; D029681:Arabidopsis Proteins; C553228:GNC protein, Arabidopsis; C553229:GNL protein, Arabidopsis; D005875:Gibberellins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D012097:Repressor Proteins; D014157:Transcription Factors