Histone Deacetylase Inhibitor Affects Apple Wax and Aroma Metabolism

Protein lysine acetylation regulates diverse biological functions. This study investigated the effect of histone deacetylase inhibitor (HDACi) treatment on apple fruit quality. HDACi treatment markedly reprogrammed gene expression, upregulating pathways for cutin, suberin, and wax biosynthesis. In "Red Delicious", treatment altered aroma profiles, increasing alcohols and aldehydes while decreasing esters. Notably, HDACi enhanced peel wax content and strongly induced MdMYB96. Functional analyses revealed that MdMYB96 activates multiple wax biosynthetic genes; its silencing reduced the wax load, while overexpression in Arabidopsis increased wax accumulation and reduced water loss. Furthermore, across eight apple cultivars, denser epicuticular wax structures correlated with higher wax gene expression and better postharvest water retention. These findings demonstrate that inhibiting histone deacetylase reshapes the balance between wax metabolism and aroma production with MdMYB96 serving as a key regulator. Thus, manipulating histone acetylation offers a promising strategy to improve apple wax biosynthesis and modify volatile profiles.