NAD-dependent protein deacetylase (By similarity). Has deacetylase activity towards H3K9Ac (By similarity). May have a function in the safeguard against genome instabiliy and DNA damage to ensure plant cell growth (By similarity). Involved in responses to ethylene leading to the transcriptional repression of some ethylene-responsive genes via the regulation of histone acetylation H3K9Ac (PubMed:29298835). H2O + N(6)-acetyl-L-lysyl-[protein] + NAD(+) = 2''-O-acetyl-ADP-D-ribose + L-lysyl-[protein] + nicotinamide Binds 1 zinc ion per subunit. Binds to the promoter region of genes influenced by ethylene (By similarity). Interacts with ENAP1; this interaction is enhanced in the presence of ethylene (PubMed:29298835). Reduced ethylene sensitivity in the double mutant srt1 srt2. Belongs to the sirtuin family. Class IV subfamily.