Tissue-Specific Regulation of Gibberellin Signaling Fine-Tunes Arabidopsis Iron-Deficiency Responses

Dev Cell. 2016 Apr 18;37(2):190-200. doi: 10.1016/j.devcel.2016.03.022.

Abstract

Iron is an essential element for most living organisms. Plants acquire iron from the rhizosphere and have evolved different biochemical and developmental responses to adapt to a low-iron environment. In Arabidopsis, FIT encodes a basic helix-loop-helix transcription factor that activates the expression of iron-uptake genes in root epidermis upon iron deficiency. Here, we report that the gibberellin (GA)-signaling DELLA repressors contribute substantially in the adaptive responses to iron-deficient conditions. When iron availability decreases, DELLAs accumulate in the root meristem, thereby restraining root growth, while being progressively excluded from epidermal cells in the root differentiation zone. Such DELLA exclusion from the site of iron acquisition relieves FIT from DELLA-dependent inhibition and therefore promotes iron uptake. Consistent with this mechanism, expression of a non-GA-degradable DELLA mutant protein in root epidermis interferes with iron acquisition. Hence, spatial distribution of DELLAs in roots is essential to fine-tune the adaptive responses to iron availability.

Keywords: Arabidopsis thaliana; DELLA; FIT; iron deficiency; root epidermis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / metabolism
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Gene Expression Regulation, Plant / physiology*
  • Gibberellins / metabolism*
  • Iron / metabolism*
  • Plant Growth Regulators / pharmacology
  • Plant Roots / drug effects
  • Plant Roots / metabolism

Substances

  • Arabidopsis Proteins
  • Basic Helix-Loop-Helix Transcription Factors
  • FIT1 protein, Arabidopsis
  • GAI protein, Arabidopsis
  • Gibberellins
  • Plant Growth Regulators
  • Iron