The VQ motif protein IKU1 regulates endosperm growth and seed size in Arabidopsis

Plant J. 2010 Aug;63(4):670-9. doi: 10.1111/j.1365-313X.2010.04271.x.


Arabidopsis seed size is regulated by the IKU pathway that includes IKU2 (a leucine-rich repeat kinase) and MINI3 (a WRKY transcription factor). We report the cloning of the IKU1 (At2g35230) gene. iku1 mutants cause reduced endosperm growth and the production of small seeds. IKU1 encodes a protein containing a VQ motif, which is a motif specific to plants. IKU1 is expressed in the early endosperm and its progenitor, the central cell. Restoration of IKU1 function in the endosperm is sufficient to rescue seed size. A genomic construct carrying mutations in the VQ motif failed to complement the iku1 mutation, suggesting an essential role for the VQ motif. IKU1 interacts with MINI3 in the yeast two-hybrid system, consistent with an IKU1 function in the IKU-MINI pathway. Our data support the proposition that endosperm development is an important determinant of seed size.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs / genetics
  • Amino Acid Sequence
  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Arabidopsis / physiology*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Arabidopsis Proteins / physiology*
  • Endosperm / genetics
  • Endosperm / growth & development*
  • Endosperm / metabolism
  • Genetic Complementation Test
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Microscopy, Confocal
  • Molecular Sequence Data
  • Mutation
  • Phenotype
  • Plants, Genetically Modified
  • Protein Binding
  • Protein Kinases / genetics
  • Protein Kinases / metabolism
  • Protein Kinases / physiology
  • Seeds / genetics
  • Seeds / metabolism
  • Seeds / physiology*
  • Sequence Homology, Amino Acid
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transcription Factors / physiology
  • Two-Hybrid System Techniques


  • Arabidopsis Proteins
  • IKU1 protein, Arabidopsis
  • Luminescent Proteins
  • MINISEED3 protein, Arabidopsis
  • Transcription Factors
  • Protein Kinases
  • HAIKU2 protein, Arabidopsis