Sl-IAA3, a tomato Aux/IAA at the crossroads of auxin and ethylene signalling involved in differential growth

J Exp Bot. 2009;60(4):1349-62. doi: 10.1093/jxb/erp009. Epub 2009 Feb 12.


Whereas the interplay of multiple hormones is essential for most plant developmental processes, the key integrating molecular players remain largely undiscovered or uncharacterized. It is shown here that a member of the tomato auxin/indole-3-acetic acid (Aux/IAA) gene family, Sl-IAA3, intersects the auxin and ethylene signal transduction pathways. Aux/IAA genes encode short-lived transcriptional regulators central to the control of auxin responses. Their functions have been defined primarily by dominant, gain-of-function mutant alleles in Arabidopsis. The Sl-IAA3 gene encodes a nuclear-targeted protein that can repress transcription from auxin-responsive promoters. Sl-IAA3 expression is auxin and ethylene dependent, is regulated on a tight tissue-specific basis, and is associated with tissues undergoing differential growth such as in epinastic petioles and apical hook. Antisense down-regulation of Sl-IAA3 results in auxin and ethylene-related phenotypes, including altered apical dominance, lower auxin sensitivity, exaggerated apical hook curvature in the dark and reduced petiole epinasty in the light. The results provide novel insights into the roles of Aux/IAAs and position the Sl-IAA3 protein at the crossroads of auxin and ethylene signalling in tomato.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Down-Regulation / drug effects
  • Ethylenes / metabolism*
  • Ethylenes / pharmacology
  • Fruit / drug effects
  • Fruit / genetics
  • Fruit / growth & development
  • Gene Expression Profiling
  • Gene Expression Regulation, Plant / drug effects
  • Genes, Plant
  • Glucuronidase / metabolism
  • Indoleacetic Acids / metabolism*
  • Indoleacetic Acids / pharmacology
  • Organ Specificity / drug effects
  • Phenotype
  • Plant Leaves / drug effects
  • Plant Leaves / metabolism
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • RNA, Antisense / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Seedlings / drug effects
  • Seedlings / genetics
  • Signal Transduction* / drug effects
  • Solanum lycopersicum / genetics
  • Solanum lycopersicum / growth & development*
  • Solanum lycopersicum / metabolism*
  • Suppression, Genetic / drug effects
  • Transcription Factors / genetics
  • Transcription Factors / metabolism


  • Ethylenes
  • Indoleacetic Acids
  • Plant Proteins
  • RNA, Antisense
  • RNA, Messenger
  • Transcription Factors
  • ethylene
  • Glucuronidase