Poster: Water Relations
Abs #
217: Functional analysis of the DREB2A protein, a transcription factor that is involved in dehydration- and salt-stress response in Arabidopsis
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Presenter: |
Sakuma, Yoh , sakuma@jircas.affrc.go.jp |
Authors | Sakuma, Yoh (A) Qin, Feng (A) Shinozaki, Kazuo (B) Yamaguchi-Shinozaki, Kazuko (A) | | Affiliations: |
(A): Japan International Research Center for Agricultural Sciences (JIRCAS)
(B): Plant Functional Genomics Group, RIKEN Genomic Sciences Center
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DREB1/CBF family and DREB2 family transcriptional factors function in low-temperature- and drought-stress-responsive gene expression, respectively. These proteins specifically bind to DRE/CRT cis-elements in promoter regions of stress-inducible genes. Though overexpression of the DREB1 genes in transgenic Arabidopsis induced strong expression of many target genes, only weak expression of target genes was observed in the transgenic Arabidopsis overexpressing the DREB2A. Therefore, a post-translational modification such as phosphorylation seems to be necessary for activation of the DREB2A protein.
To characterize activation mechanism of the DREB2A in response to osmotic stress, we analyzed the trans-activity of several C-terminal or internal deletion mutants of the DREB2A using Arabidopsis T87 cell protoplasts. The C-terminal-deleted DREB2A that lacks a region between a.a. 254 and 335 no longer activated expression of a reporter gene, which suggests that a transcriptional activation domain of DREB2A exists in that region. On the other hand, internal deletion between a.a. 136 and 165 of the DREB2A increased expression of the reporter gene at 6 times than the full length DREB2A protein did. This region may play an important role in the activation of DREB2A. We generated transgenic Arabidopsis plants that overexpressed a constitutive active form of the DREB2A lacking the region between a.a. 136 and 165. The transgenic plants showed growth retardation like those overexpressing the DREB1 protein. Microarrray analysis revealed that many water-stress inducible genes expressed in the transgenic plants even at non-stress condition.
