## 1 Introduction
Phytochromes, which are essential for red and far-red light responses, exist in two states: Pr, absorbing red light (650-670 nm), and Pfr, absorbing far-red light (705-740 nm) [16; 20]. Pr converts to the active Pfr upon absorbing red light, and Pfr reverts to Pr upon absorbing far-red light. Phototropins, membrane-bound and activated by blue light, are critical in photosynthesis, regulating chloroplast movement, stomatal dynamics, and optimizing carbon dioxide and water exchange [16; 20; 21]. The ZTL/FKF1/LKP2 complex, sensitive to blue and UV-A wavelengths, governs circadian rhythms and flowering [16; 20; 21]. UVR8 receptors, detecting UV-B radiation, mitigate its harmful effects by inducing gene expression linked to antioxidant production. They also regulate vital plant responses, such as stomatal behavior and chlorophyll balance [16; 20; 21]. These advanced systems allow plants to adjust their growth and development, ensuring survival and optimal performance in dynamic light environments [16; 20; 21; 22; 23; 24]. Photoreceptor-mediated light perception initiates a signaling cascade that markedly changes gene expression and influences key plant physiological responses [16; 20; 21]. In Arabidopsis, a staggering 20% of genes are regulated by light, with the bZIP transcription factor ELONGATED HYPOCOTYL 5 (HY5) emerging as a pivotal regulator in light-mediated development and metabolism. HY5 integrates light signals with hormonal and nutrient pathways, while Phytochrome Interacting Factors (PIFs) serve as strong negative regulators of this pathway. The E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) controls these transcription factors by targeting them for degradation. HY5's versatility spans light, hormone, and stress signaling, operating downstream of phytochromes, cryptochromes, and UVR8 to regulate gene expression [16; 20; 21]. Its interactions with SUPPRESSOR OF PHYA (SPA) proteins and other transcription factor families highlight its central role in light signaling. The transcription of light-regulated genes significantly impacts plant growth, development, and seasonal adaptation [16; 20; 21]. Hormones such as auxin, ethylene, jasmonic acid, gibberell acid, and abscisic acid interact with light signaling pathways, influencing both vegetative and reproductive stages [16; 20; 21; 25; 26]. Recent advancements have clarified hormone signaling (Figure 1) mechanisms, revealing how light perception profoundly affects hormonal regulation in processes like germination, flowering, and morphogenesis [16; 20; 21]. The circadian clock aligns plant physiology and development with daily and seasonal environmental changes, controlling processes such as photosynthesis and stomatal movements [17; 26]. Chromatin regulation creates rhythmic gene expression networks that are active at specific times and managed by the clock through feedback loops, involving MYB transcription factors (Figure 1) [17; 26]. Shade avoidance, which is crucial for survival, is linked to hormone signaling, such as the auxin-mediated elongation of hypocotyls and petioles [17; 25; 26; 27]. Plants detect shading from neighboring vegetation through dramatic shifts in the red-to-far-red (R-FR) light ratio, sensed by phytochromes. The response cascade involves hormones like gibberellins (GA), ethylene (ET), auxin, Brassinosteroids, cytokins (CK), and jasmonic acid (JA) (Figure 1) [17; 25; 26; 27]. Auxin plays a pivotal role in elongation phenotypes and its pathway is tightly regulated when sensing nearby plants. Auxin-related genes dominate a significant portion of the shade avoidance transcriptome [17; 25; 26; 27]. The regulation of apical dominance is another critical aspect governed by endogenous auxins and cytokins. These growth regulators are instrumental in nutrient diversion, gene expression modulation of axillary bud growth, and fine-tuning the auxin/cytokinin ratio (Figure 1) [17; 25; 26; 27].