The GATA-type transcription factors GNC and GNL/CGA1 repress gibberellin signaling downstream from DELLA proteins and PHYTOCHROME-INTERACTING FACTORS

Genes Dev. 2010 Sep 15;24(18):2093-104. doi: 10.1101/gad.594910.

Abstract

The phytohormone gibberellin (GA) regulates various developmental processes in plants such as germination, greening, elongation growth, and flowering time. DELLA proteins, which are degraded in response to GA, repress GA signaling by inhibitory interactions with PHYTOCHROME-INTERACTING FACTOR (PIF) family transcription factors. How GA signaling is controlled downstream from the DELLA and PIF regulators is, at present, unclear. Here, we characterize GNC (GATA, NITRATE-INDUCIBLE, CARBON-METABOLISM INVOLVED) and GNL/CGA1 (GNC-LIKE/CYTOKININ-RESPONSIVE GATA FACTOR1), two homologous GATA-type transcription factors from Arabidopsis thaliana that we initially identified as GA-regulated genes. Our genetic analyses of loss-of-function mutants and overexpression lines establish that GNC and GNL are functionally redundant regulators of germination, greening, elongation growth and flowering time. We further show by chromatin immunoprecipitation that both genes are potentially direct transcription targets of PIF transcription factors, and that their expression is up-regulated in pif mutant backgrounds. In line with a key role of GNC or GNL downstream from DELLA and PIF signaling, we find that their overexpression leads to gene expression changes that largely resemble those observed in a ga1 biosynthesis mutant or a pif quadruple mutant. These findings, together with the fact that gnc and gnl loss-of-function mutations suppress ga1 phenotypes, support the hypothesis that GNC and GNL are important repressors of GA signaling downstream from the DELLA and PIF regulators.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Basic Helix-Loop-Helix Transcription Factors / genetics
  • Basic Helix-Loop-Helix Transcription Factors / metabolism*
  • GATA Transcription Factors / genetics
  • GATA Transcription Factors / metabolism
  • Gene Expression Regulation, Plant
  • Germination / genetics
  • Gibberellins / metabolism*
  • Guanine Nucleotide Exchange Factors / genetics
  • Guanine Nucleotide Exchange Factors / metabolism
  • Mutation
  • Plant Growth Regulators / metabolism*
  • Plants, Genetically Modified
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Signal Transduction
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • Arabidopsis Proteins
  • Basic Helix-Loop-Helix Transcription Factors
  • GATA Transcription Factors
  • GNC protein, Arabidopsis
  • GNL protein, Arabidopsis
  • GNL1 protein, Arabidopsis
  • Gibberellins
  • Guanine Nucleotide Exchange Factors
  • PIF1 protein, Arabidopsis
  • Plant Growth Regulators
  • Repressor Proteins
  • Transcription Factors

Associated data

  • GEO/GSE21256