Analysis of functional domains and binding sequences of Arabidopsis transcription factor ESR1

The Arabidopsis ESR1 is thought to be a key gene for commitment to in vitro shoot regeneration in tissue culture. The ESR1 gene encodes a putative transcription factor. We examined the DNA-binding potential for specific sequences. Recombinant ESR1 protein specifically bound to the GCC box, known as the ethylene-responsive element. In addition, ESR1 was localized to the nucleus when expressed in onion epidermal cells. Deletion experiments revealed that the DNA-binding domain or the C-terminal region of ESR1 is essential for ESR1 overexpression to enhance shoot regeneration. The C-terminal region may be involved in transcriptional regulation by ESR1. These results suggest that ESR1 functions as a transcription factor and that its transcriptional regulation is important for the initiation of shoot regeneration.