Responsible for the deacetylation of lysine residues on the N-terminal part of the core histones (H2A, H2B, H3 and H4). Histone deacetylation gives a tag for epigenetic repression and plays an important role in transcriptional regulation, cell cycle progression and developmental events. Histone deacetylases act via the formation of large multiprotein complexes (Probable). Regulates negatively the expression of the NAC48/NAC6 gene that controls root growth in seedlings. Epigenetically represses the expression of NAC48/NAC6 by deacetylating 'Lys-9' (H3K9ac), 'Lys-14' (H3K14ac) and 'Lys-18' (H3K18ac) of histone H3, and 'Lys-5' (H4K5ac), 'Lys-12' (H4K12ac) and 'Lys-16' (H4K16ac) of histone H4 (PubMed:19453457). Functions in the regulation of gene expression in the whole genome (PubMed:12581311). Acts as chromatin remodeling regulator to promote the formation of a repressive chromatin state. Functions with MODD via its interaction with TPR3, to down-regulates the histone acetylation level at BZIP46 target genes. BZIP46 is a positive regulator of abscisic acid (ABA) signaling and drought stress tolerance (PubMed:27468891). H2O + N(6)-acetyl-L-lysyl-[histone] = acetate + L-lysyl-[histone] Binds 1 zinc ion per subunit. Interacts with TPR3. Expressed in roots and leaves. Down-regulated by drought and salt stresses. Plants over-expressing HDAC1 exhibit increased growth rate and altered plant architecture (PubMed:12581311). Plants silencing HDAC1 exhibit narrow leaves, reduced diameter of stems and reduced plant height (PubMed:19664599). Belongs to the histone deacetylase family. HD Type 1 subfamily.