NAD-dependent protein deacetylase. Has deacetylase activity towards H3K9Ac. May have a function in the safeguard against genome instabiliy and DNA damage to ensure plant cell growth. H2O + N(6)-acetyl-L-lysyl-[protein] + NAD(+) = 2''-O-acetyl-ADP-D-ribose + L-lysyl-[protein] + nicotinamide Binds 1 zinc ion per subunit. Enhances histone H3K9 acetylation on transposable elements and promoters of hypersensitive response (HR)-related genes. This leads to increased HR-related gene expression, hydrogen peroxide production, DNA fragmentation, and programmed cell death. Belongs to the sirtuin family. Class IV subfamily.