Light regulates tomato fruit metabolome via SlDML2-mediated global DNA demethylation.

Modifying the light formula is a central strategy for improving the yield and quality of fruits and vegetables in agriculture. While light signals have long been acknowledged as primary factors in regulating plant growth and development, their role in reprogramming metabolic networks is not well understood. Using tomato as a model, we demonstrate that supplementation with red or blue light induces metabolic shifts in tomato fruit. Through the creation of the Tomato Light-induced Expression Database (TomLED), we identified extensive transcriptomic and metabolic changes in tomato fruit under varying light conditions. Notably, the induction of key master regulators and metabolic genes is mediated by increased genome-wide DNA demethylation, facilitated by SlDML2. Additionally, we show that SlHY5, a central regulator in the light signaling pathway, directly induces the expression of SlDML2. This study reveals the molecular mechanisms by which light regulates the plant epigenome and establishes a direct link between light signals and plant metabolism.