Using PCR-select cDNA subtraction, we identified the genes that are predominantly expressed in the shooty callus induced by suppression of the CHRK1 receptor-like kinase gene. One of the identified genes encoded a novel AP2/EREBP-type transcription factor, and it was highly expressed in various types of tobacco callus including the CHRK1 transgenic callus, hence designated as Nicotiana tabacum Callus-Expressing Factor 1 NtCEF1. The NtCEF1-GFP fusion protein was localized in the nucleus. The full length and the C-terminal acidic region of NtCEF1 could function as a transactivator in yeast, when fused to the LexA DNA binding domain. Expression of the NtCEF1 gene was induced by ethylene and by various abiotic stresses. Gel retardation assay revealed that NtCEF1 could bind specifically to the GCC box as well as to the C/DRE motif, albeit less strongly. Interestingly, NtCEF1 overexpression in Arabidopsis resulted in constitutive expression of various ethylene-responsive and defense genes that contain the GCC box in the promoter-but none of the genes containing the upstream C/DRE elements-indicating that NtCEF1 preferentially recognizes the GCC box in vivo. Furthermore, the NtCEF1-overexpressing Arabidopsis plants exhibited enhanced resistance to a bacterial pathogen, Pseudomonas syringae pv. tomato DC3000. Taken together, these results suggest that NtCEF1 is a transcription factor preferentially activating the GCC box-containing defense genes, and that it modulates increased resistance against the biotic stress by activation of the downstream gene expression.
Bibliographical noteFunding Information:
Acknowledgments The authors wish to thank Dr. Moonil Kim, Dr. Hye Sun Cho, Joon-Woo Ahn, and Dr. Sang Sook Lee (Korea Research Institute of Bioscience and Biotechnology, Taejon, Korea) for technical help. This research was supported by grants from the Plant Diversity Research Center of the 21st Century Frontier Research Program (to H.-S. Pai and W.T. Kim), the Molecular and Cellular BioDiscovery Research Program (to H.-S. Pai), and the Plant Metabolism Research Center (at Kyung Hee University) of the Science Research Center Program (to W.T. Kim), all of which are funded by the Ministry of Science and Technology of the Korean government. The nucleotide sequence data reported here have been deposited in the GenBank database under EMBL accession number AY286010 (NtCEF1).
All Science Journal Classification (ASJC) codes
- Plant Science