The GCN4 motif in a rice glutelin gene is essential for endosperm-specific gene expression and is activated by Opaque-2 in transgenic rice plants

Plant J. 1998 Jun;14(6):673-83. doi: 10.1046/j.1365-313x.1998.00167.x.


The GCN4 motif is conserved in a number of seed storage protein genes, and promoter fragments containing this motif have been shown to be involved in controlling seed-specific expression of the genes studied. All genes encoding the rice seed storage protein glutelin contain the GCN4 motif at similar sites in their 5' flanking regions. Using a stable homologous transgenic system, we have analysed the promoter of the rice glutelin gene GluB-1 and demonstrated that the GCN4 motif functions as an essential cis-element for endosperm-specific gene expression. Moreover, a 21 bp GluB-1 promoter fragment spanning the GCN4 motif, as a multimer, directed GUS gene expression in endosperm of transgenic rice plants, when fused directly to the core promoter (-46) of CaMV 35S. In transiently transfected rice protoplasts, over a hundred-fold transactivation was observed from the 21 bp sequence by the bZIP type transcriptional activator Opaque-2 (O2) co-expressed under a CaMV 35S promoter. The transactivation was also evident in transgenic plants containing both O2 and the 21 bp sequence/GUS fusion. The O2-mediated activation requires binding of O2 to an intact GCN4 motif. Our results suggest that a bZIP protein functionally similar to O2 may exist in rice and participate in controlling the endosperm-specific expression of GluB-1 through the GCN4 motif.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Artificial Gene Fusion
  • Base Sequence
  • Conserved Sequence
  • DNA, Plant / genetics
  • DNA-Binding Proteins / genetics*
  • Gene Expression Regulation, Plant
  • Genes, Plant*
  • Genes, Reporter
  • Glucuronidase / genetics
  • Glutens / genetics*
  • Histocytochemistry
  • Molecular Sequence Data
  • Oryza / genetics*
  • Oryza / metabolism
  • Plant Proteins / genetics
  • Plants, Genetically Modified
  • Promoter Regions, Genetic
  • Transcription Factors / genetics*
  • Transcriptional Activation


  • DNA, Plant
  • DNA-Binding Proteins
  • Plant Proteins
  • Transcription Factors
  • opaque-2 protein, Zea mays
  • Glutens
  • Glucuronidase