BIGPETALp, a bHLH transcription factor is involved in the control of Arabidopsis petal size

EMBO J. 2006 Aug 23;25(16):3912-20. doi: 10.1038/sj.emboj.7601270. Epub 2006 Aug 10.


In Arabidopsis, APETALA1, PISTILLATA, APETALA3 and SEPALLATA interact to form multimeric protein complexes required to specify petal identity. However, the downstream events that lead to petal specific shape and size remain largely unknown. Organ final size can be influenced by cell number or cell expansion or both. To date, no gene that specifically limits petal size by controlling postmitotic cell expansion has been identified. Here we have identified a novel petal-expressed, basic helix-loop-helix encoding gene (BIGPETAL, BPE) that is involved in the control of petal size. BPE is expressed via two mRNAs derived from an alternative splicing event. The BPEub transcript is expressed ubiquitously, whereas the BPEp transcript is preferentially expressed in petals. We demonstrate that BPEp is positively regulated downstream of APETALA3, PISTILLATA, APETALA1 and PISTILLATA3 and is negatively regulated downstream of AGAMOUS. Plants that lack the petal-expressed variant BPEp have larger petals as a result of increased cell size, showing that BPEp interferes with postmitotic cell expansion. BPEp is therefore a part of the network that links the patterning genes to final morphogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing
  • Amino Acid Sequence
  • Arabidopsis / metabolism
  • Arabidopsis / physiology*
  • Arabidopsis Proteins / biosynthesis
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / physiology*
  • Base Sequence
  • Basic Helix-Loop-Helix Transcription Factors / biosynthesis
  • Basic Helix-Loop-Helix Transcription Factors / genetics
  • Basic Helix-Loop-Helix Transcription Factors / physiology*
  • Cell Enlargement
  • Cell Proliferation
  • Flowers / metabolism
  • Flowers / physiology*
  • Gene Expression Regulation, Plant
  • Mitosis
  • Molecular Sequence Data
  • RNA, Messenger / biosynthesis


  • Arabidopsis Proteins
  • BIGPETAL protein, Arabidopsis
  • Basic Helix-Loop-Helix Transcription Factors
  • RNA, Messenger