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

## TL;DR

This study shows how Arabidopsis plants respond to a new artificial light system that mimics sunlight, affecting their growth and gene activity.

## Contribution

The study reveals how specific genes respond to a novel artificial light system, offering insights into plant adaptation to indoor lighting.

## Key findings

- CoeLux® light alters gene expression related to light perception and plant development.
- Plants lacking HY5 or HFR1 show altered growth under CoeLux® light, confirming their role in adaptation.
- CoeLux® induces gene responses similar to those in shaded or low-light conditions.

## Abstract

Plants rely on light not only for photosynthesis but also to regulate their growth and development. This study investigated how Arabidopsis thaliana, a model plant species, responds at the molecular level to CoeLux®, an innovative artificial lighting system that closely mimics natural sunlight. Unlike conventional lights used in plant growth, CoeLux® produces a unique light spectrum with reduced blue light and a higher blue-to-green ratio, creating conditions that resemble light found in shaded environments. Our findings show that CoeLux® lighting influences the activity of key genes involved in light perception and plant development, leading to changes similar to those seen in low-light or shaded conditions. Plants lacking some of these genes showed altered growth under CoeLux® light, confirming their role in adapting to this artificial environment. This research helps deepen our understanding of how plants react to artificial light sources and can support better design of indoor growing systems for both plant health and human well-being.

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 Arabidopsis thaliana 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.