Arabidopsis Thaliana Histone Deacetylase 1 ( Athd 1 ) and Epigenetic Regulation

Arabidopsis thaliana Histone Deacetylase 1 (AtHD1) and Epigenetic Regulation. (May 2004) Lu Tian, B.S., Fudan University, P.R.China Chair of Advisory Committee: Dr. Z. Jeffrey Chen Epigenetic regulation is a mechanism by which heritable changes in gene expression are controlled by chromatin status rather than primary DNA sequence. Changes in chromatin structure affect accessibility of DNA elements to the transcriptional machinery and thus affect transcription activity of the gene. A key event in this process is reversible modification of core histones, which is catalyzed by histone acetyltransferases (HATs) and histone deacetylases (HDs, HDAs, or HDACs). In general, histone deacetylation is related to transcriptional gene silencing, whereas acetylation is associated with gene activation. To study the role of histone deacetylase in plant gene regulation and development, we generated constitutive antisense histone deacetylase 1 (CASH) transgenic plants. AtHD1 is a homolog of RPD3 protein, a global transcriptional regulator in yeast. Expression of the antisense AtHD1 caused dramatic reduction in endogenous AtHD1 transcription, resulting in accumulation of acetylated histones. Down-regulation of histone deacetylation caused a variety of growth and developmental abnormalities and ectopic expression of tissue-specific genes. However, changes in