Ethylene-responsive gene expression during carnation flower senescence

Ethylene activates the transcription of a number of genes at the onset of senescence in carnation newer petals. A glutathione S-transferase gene (GST1) has been used as a model to study the mechanism by which ethylene induces gene expression. A 126 bp region of the GST1 promoter sequence has been identified as an ethylene-responsive enhancer element ERE). Nuclear proteins from senescing petals recognize a 22 bp sequence within the ERE, and mutations in this sequence disrupt the interaction between the protein and DNA. The wild-type ERE sequence was used to isolate a cDNA encoding a sequence-specific DNA binding protein. Nucleotide sequencing and deduced amino acid sequence analysis of this cDNA predicted a 32 kDa protein that we have designated CEBP-1. The mRNA expression pattern of CEBP-1 suggests that it is not transcriptionally regulated by ethylene. The amino acid sequence homology of CEBP-1 with other plant nucleic acid binding proteins indicates a conserved nucleic acid binding domain. Within this domain are two highly conserved RNA-binding motifs. Taken together, these data suggest that CEBP-1 represents a component of a DNA-binding complex involved in the transcriptional activation of GST1 by ethylene.