A role for AUXIN RESISTANT3 in the coordination of leaf growth

Plant Cell Physiol. 2010 Oct;51(10):1661-73. doi: 10.1093/pcp/pcq123. Epub 2010 Aug 24.


The characteristically flat structure of Arabidopsis thaliana vegetative leaves requires coordinating the growth of the epidermal, palisade mesophyll, spongy mesophyll and vascular tissues. Mutations disrupting such coordination or the specific growth properties of any of these tissues can cause hyponasty, epinasty, waviness or other deviations from flatness. Here, we show that the incurvata6 (icu6) semi-dominant allele of the AUXIN RESISTANT3 (AXR3) gene causes leaf hyponasty. Cotyledons and leaves of icu6/AXR3 plants exhibited reduced size of adaxial pavement cells, and abnormal expansion of palisade mesophyll cells. Enhanced auxin responses in the adaxial domain of icu6/AXR3 developing cotyledons and leaves correlated with increased cell divisions in the adaxial epidermis. Leaf incurvature in icu6/AXR3 leaves was alleviated by loss-of-function alleles of the ASYMMETRIC LEAVES1 (AS1) and AS2 genes, which restrict the expression of class I KNOX genes to the shoot apical meristem and regulate cell proliferation in leaf primordia. Taken together, our results suggest that an interaction between auxin responses and the AS1-AS2 pathway coordinates tissue growth during Arabidopsis thaliana leaf expansion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Cloning, Molecular
  • Gene Expression Regulation, Plant
  • Indoleacetic Acids / metabolism*
  • Mutation
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Phenotype
  • Plant Epidermis / cytology
  • Plant Epidermis / growth & development
  • Plant Growth Regulators / metabolism
  • Plant Leaves / cytology
  • Plant Leaves / growth & development*
  • RNA, Plant / genetics
  • Transcription Factors / genetics
  • Transcription Factors / metabolism


  • AS2 protein, Arabidopsis
  • ASYMMETRIC LEAVES1 protein, Arabidopsis
  • AXR3 protein, Arabidopsis
  • Arabidopsis Proteins
  • Indoleacetic Acids
  • Nuclear Proteins
  • Plant Growth Regulators
  • RNA, Plant
  • Transcription Factors