Lysine Deacetylation: An Emerging Molecular Switch of Plant Light Signaling

Lysine acetylation, dynamically regulated through the balanced activities of histone deacetylases (HDACs) and histone acetyltransferases (HATs), plays dual roles in chromatin regulation and post-translational regulation. In plant light signaling, HDACs are recruited by ELONGATED HYPOCOTYL 5 (HY5) and PHYTOCHROME-INTERACTING FACTORS (PIFs) to regulate light-responsive gene expression via histone deacetylation during seedling development. Recent studies have expanded this classical framework by revealing non-histone functions of HDACs. Their works demonstrate that two HDACs, HDT2 and HDA9, directly deacetylate the far-red photoreceptor phyA and the blue-light photoreceptor phot1, respectively, thereby modulating their stability and activity to downstream light signaling. These findings identify non-histone deacetylation as an emerging regulatory switch linking photoreceptor stability and activity to downstream light signaling and reveal pivotal non-histone roles of HDACs in photomorphogenesis and phototropism in Arabidopsis thaliana. In this minireview, we outline a multilayered regulatory network that integrates HDAC-mediated histone and non-histone deacetylation to coordinate transcriptional reprogramming with photoreceptor stability and activation, thereby ensuring precise and adaptable light responses in plants.