Abstract
We have reported that transgenic Arabidopsis overexpressing salinity-responsive DDF1 gene (35S::DDF1) show dwarfism due to gibberellin deficiency caused through induction of AtGA2ox7 gene. DDF1 encodes AP2 DNA-binding domain that is highly similar to that of DREB/CBF transcriptional activators. We have also reported that RD29A gene, which has DRE motifs in their promoter, is induced in the 35S::DDF1 plants, indicating DDF1 is capable of binding DRE and/or DRE-Like motif. Transactivation assay showed that transient overexpression of DDF1 induced the expression LUC reporter gene under the promoter of RD29A or AtGA2ox7 in Arabidopsis leaves. Gel shift assay showed that DDF1 bound the DRE motif of the RD29A promoter or DRE-like motifs found in the AtGA2ox7 promoter. These results indicate that DDF1 is transcriptional activator, directly capable of activating these target genes.
