Phytohormonal Regulation of Plant Development in Response to Fluctuating Light Conditions

Plants have developed adaptive mechanisms to maximize their productivity and fitness under varying light conditions. They react to diverse environmental cues and make adjustments to regulate their growth and developmental patterns. Light is one of the crucial environmental factors that directly affects plant development. Light signals are critical for seed germination, photomorphogenesis, and flowering; they assist in light collection through architectural modifications during phototropism and shade avoidance. Photoreceptors detect light signals, activating downstream signaling pathways. Phytohormone-mediated signaling integrates physiological responses to light perception while regulating photoreceptors and their primary interactions. Hormone levels and signaling fluctuations are often employed to trigger growth and development to adjust appropriately in response to changes in light. Phytohormones are critical for a variety of developmental processes, from organ formation to senescence, because they are growth and developmental regulators. Phytohormones such as auxin, cytokinin, abscisic acid, brassinosteroid, ethylene, gibberellin, jasmonic acid, strigolactone, and karrikin regulate and coordinate developmental processes in response to fluctuations in light conditions. Furthermore, the circadian clock regulates plant development by combining light signals with several hormone pathways. This review aims to provide a comprehensive overview of light-regulated processes in plants throughout their life cycle, including the way light signals influence phytohormonal regulation. We provide insight into the mechanisms that allow plants to flourish in environments of variable light by looking into well-established connections between perception of light and hormone fluctuations.