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Molecular mechanism of Arabidopsis CBF mediated plant cold-regulated gene transcriptional activation

Wang, Zhibin
http://rave.ohiolink.edu/etdc/view?acc_num=osu1158600906

Abstract Details

2006, Doctor of Philosophy, Ohio State University, Horticulture and Crop Science.
To elucidate the molecular mechanisms of plant cold acclimation, I focused on the understanding of Arabidopsis CBF1 (C-repeat binding factor 1) mediated plant cold-regulated (COR) gene trans-activation by analyzing the CBF1 activation domain (AD) and determining the epigenetic regulation on COR gene that is played by the putative associated chromatin-modifying factors of CBF1AD. To identify critical amino acid residues in CBF1 for trans-activation, I employed strategies of alanine-scanning mutagenesis, truncation mutation, leucine substitution. Mutants were fused to the heterologous GAL4 DNA binding domain and then assayed in yeast reporter strain and Arabidopsis reporter lines. Data suggest 1) there are multiple hydrophobic clusters redundantly contributing to trans-activation; 2) the conserved alanines are important for the maximal trans-activity; 3) the WSY motif has an inhibitive effect on trans-activation. These critical motifs are well conserved among homologs across plant taxa. Furthermore, the growth retardation resulted from the overexpression of a trans-activator in Arabidopsis is related to the trans-activity of that trans-activator. To determine the role of epigenetic control of transcription in the regulation of COR gene expression, I did RNA gel blot analyses and plant freezing assays with several methylation mutant lines. Data indicated that a single T-DNA integration locus with multiple copies of rearranged transgene in several methylation mutants negatively affected the expression of CBF1, COR15a, and ABF1 gene. Next, I also examined the role of the putative direct target of CBF1 activation domain, the homologs of yeast Tra1 (transcription domain-associated protein 1), in the regulation of COR gene expression. Arabidopsis encodes two Tra1-like genes. We named AtTra1-2 and AtTra1-4. The double homozygous T-DNA mutants were lethal, indicating their essential nature. RT-PCR analyses suggested that T-DNA insertions resulted in truncated transcripts. RNAi mediated knockdown expression of AtTra1 resulted in pleiotropic phenotypes on plant growth and development. AtTra1-2 promoter::GUS fusion constructs indicated that AtTra1-2 was expressed in miotically active tissues. Thus I conclude that AtTra1 genes are essential to Arabidopsis embryogenesis, growth and development.
Eric Stockinger (Advisor)
255 p.
Arabidopsis; CBF1; plant cold acclimation; transcriptional activation; mutational analysis; chromatin remodeling

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Citations

  • Wang, Z. (2006). Molecular mechanism of Arabidopsis CBF mediated plant cold-regulated gene transcriptional activation [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1158600906

    APA Style (7th edition)

  • Wang, Zhibin. Molecular mechanism of Arabidopsis CBF mediated plant cold-regulated gene transcriptional activation. 2006. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1158600906.

    MLA Style (8th edition)

  • Wang, Zhibin. "Molecular mechanism of Arabidopsis CBF mediated plant cold-regulated gene transcriptional activation." Doctoral dissertation, Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1158600906

    Chicago Manual of Style (17th edition)

osu1158600906
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© 2006, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.