The ULTRACURVATA2 gene of Arabidopsis encodes an FK506-binding protein involved in auxin and brassinosteroid signaling

Plant Physiol. 2004 Jan;134(1):101-17. doi: 10.1104/pp.103.032524.


The dwarf ucu (ultracurvata) mutants of Arabidopsis display vegetative leaves that are spirally rolled downwards and show reduced expansion along the longitudinal axis. We have previously determined that the UCU1 gene encodes a SHAGGY/GSK3-like kinase that participates in the signaling pathways of auxins and brassinosteroids. Here, we describe four recessive alleles of the UCU2 gene, whose homozygotes display helical rotation of several organs in addition to other phenotypic traits shared with ucu1 mutants. Following a map-based strategy, we identified the UCU2 gene, which was found to encode a peptidyl-prolyl cis/trans-isomerase of the FK506-binding protein family, whose homologs in metazoans are involved in cell signaling and protein trafficking. Physiological and double mutant analyses suggest that UCU2 is required for growth and development and participates in auxin and brassinosteroid signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / anatomy & histology
  • Arabidopsis / genetics*
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism*
  • Base Sequence
  • DNA, Plant / genetics
  • Gene Expression / drug effects
  • Genes, Plant*
  • Genetic Complementation Test
  • Indoleacetic Acids / metabolism
  • Mutation
  • Peptidylprolyl Isomerase / genetics
  • Peptidylprolyl Isomerase / metabolism
  • Phenotype
  • Plant Growth Regulators / metabolism
  • Plant Growth Regulators / pharmacology
  • Plant Leaves / anatomy & histology
  • Signal Transduction
  • Tacrolimus Binding Proteins / genetics*
  • Tacrolimus Binding Proteins / metabolism*


  • Arabidopsis Proteins
  • DNA, Plant
  • Indoleacetic Acids
  • Plant Growth Regulators
  • UCU1 protein, Arabidopsis
  • Tacrolimus Binding Proteins
  • Peptidylprolyl Isomerase