Poster: Chromatin Remodeling & Epigenetics

Abs # 1028: Rice histone deacetylase: a global regulator in gene expression

Presenter:	Kim, Ju-Kon , jukon@bio.mju.ac.kr
Authors	Kim, Ju-Kon  (A)   Jang, In-Cheol  (A)   Pahk, Yoon-Mok  (A)   Kim, Sujung  (A)   Song, Sang Ik  (A)   Nahm, Baek Hie  (A)
Affiliations:	(A): Myongji University

Histone deacetylases (HDACs) modulate chromatin structure and transcription. We isolated the rice OsHDAC1, 2, and 3 genes, which are related to the RPD3 family of histone deacetylases. Genomic structures and Southern blot analyses revealed that OsHDAC1, 2, and 3 contained 7, 6, and 7 exons, respectively, and constituted a class I-type family in the rice genome. OsHDAC1 was expressed at similar levels in the leaves, roots, and callus cells, whereas OsHDAC2 and 3 were expressed in the roots and callus cells, but not in the leaves, exhibiting distinct tissue specificity. To explore the role of histone deacetylases in transgenic plants, we inserted the OsHDAC1 cDNA fragment into the expression vector Ai::OsHDAC1 under the control of the ABA-inducible promoter Ai, and transformed the construct into rice. Levels of mRNA, protein, and HDAC activity were significantly increased in Ai::OsHDAC1 callus cells. The amount of tetra-acetylated H4 in the transgenic cells was greatly reduced, and the reduction was abolished upon treatment with trichostatin A. These results demonstrate that OsHDAC1 overexpression in transgenic cells both yields enzymatically active HDAC complexes and induces changes in histone acetylation in vivo. The overexpression leads to a range of novel phenotypes, involving increased growth rate and altered plant architecture, suggesting that OsHDAC1 functions in the genome-wide programming of gene expression. Microarray analysis on OsHDAC1 overexpressor will be discussed.