The Gene Expression of the Transcription Factors HY5 and HFR1 Is Involved in the Response of Arabidopsis thaliana to Artificial Sun-like Lighting Systems

Plants can sense light signals using specific photoreceptors, activating light signaling pathways to precisely regulate photomorphogenesis and shade-avoidance responses. This study examines the molecular responses of <i>Arabidopsis thaliana</i> to the CoeLux^® lighting system, a unique LED-based light source designed to simulate natural sunlight. Previous studies found that the CoeLux^® light type, characterized by a higher blue-to-green ratio and reduced blue light levels, stimulates responses in plants comparable to those displayed in shade conditions. This research compared the effects of CoeLux^® lighting to conventional high-pressure sodium (HPS) lamps, focusing on the expression of critical photomorphogenesis-related genes under both long- and short-term light treatments. Lower HY5 and elevated HFR1 expression levels were observed under the CoeLux^® light type and low-intensity light conditions. On the contrary, the influence of the CoeLux^® light type on COP1 and PIFs expression levels seems more marginal. These responses suggest a complex regulation involving both gene expression and protein-level adjustments. Additionally, mutant plants lacking these essential regulatory genes displayed altered morphologies under CoeLux^® light, underscoring the functional contribution of these genes in the adaptation to light. Our findings are twofold, advancing the understanding of plant-light relationships and plant adaptation to artificial light environments. These may foster strategies for optimizing indoor plant growth under simulated sunlight conditions.