Poster: Regulation of gene expression

Abs # 783: The Arabidopsis ABI5 bZIP gene alters the global pattern of embryo-related and ABA-regulated gene expression

Presenter:	Hur, Jungim , jhur@bio.tamu.edu
Authors	Hur, Jungim  (A) (B)  Damaj, Mona  (A)   Beremand, Phillip  (A)   Collins, Jenniffer  (A)   Hur, Junguk  (C)   Thomas, Terry  (A) (B)
Affiliations:	(A): Deaprtment of Biology, Texas A&M University (B): Interdisciplinary Program of Molecular and Environmental Plant Sciences, Texas A&M University (C): Bioiformatics Units, ISTECH Inc.

Five Arabidopsis genes that encode basic leucine zipper (bZIP) transcription factors and bind to the promoter of the ABA-regulated late embryogenesis abundant (lea) Dc3 gene were isolated in our laboratory and designated as Dc3-promoter binding factors (AtDPBFs). These genes include AtDPBF-1 which is identical to the ABA insensitive 5 (ABI5) and are considered members of the ABI5 bZIP subfamily of transcription factors that regulate key aspects of plant seed development and abscisic acid (ABA)-signaling. To understand the ABI5 and/or ABA-regulated gene expression on a global scale, we have conducted DNA microarray and oligoarray analyses of the ABI5/AtDPBF-1 T-DNA mutant background during seed development and vegetative growth in the presence of ABA. We have identified ABI5- and ABI5/ABA-regulated genes with this expression profiling approach. Interestingly, several ABI5 bZIP subfamily members were found to be regulated by ABI5 during seed maturation such as AtDPBF-2, AtDPBF-4, AtDPBF-5, ABF2, AtbZIP13 and GBF4. Other ABI genes like ABI2 (protein phosphatase 2C) and ABI4 were also regulated by ABI5, as were other related transcription factors (LEC1 and AtAF1 and 2), and some seed storage proteins (AtEm1, AtEM6, dehydrin and LEA). Few genes were affected by ABI5 and ABA in vegetative tissues, indicating a tight coupling between ABI5 function and ABA signaling. In silico analysis of the 5' upstream sequences of the ABI5/ABA-regulated genes identified consensus ABA responsive elements and/or seed-specific regulatory elements, indicating that these genes could be direct targets of ABI5. This functional genomics analysis will contribute to understanding how ABI5/AtDPBF-1 globally regulates seed-specific and/or ABA-responsive gene expression during plant development.