Photobiology

Photobiology is the scientific study of how light interacts with living organisms. It encompasses the generation and perception of light by biological systems, and how light governs physiological and ecological processes. Wavelengths from ultraviolet through visible to near-infrared influence cells and tissues, enabling photosynthesis, vision, circadian regulation, photomorphogenesis, phototaxis, and photodamage.

Key mechanisms include photoreceptors such as opsins involved in animal vision, phytochromes, cryptochromes and phototropins in plants and algae, and microbial rhodopsins in microorganisms. These pigments absorb photons, triggering conformational changes that initiate signaling cascades, gene expression, and metabolic adjustments. Photobiology also covers photosynthetic light reactions, energy capture by chlorophyll and accessory pigments, electron transport, and regulation by light quality and intensity. Light can also generate reactive oxygen species, influencing phototoxic effects and protective responses such as DNA repair and antioxidant defenses.

Subfields include plant photobiology, animal vision and retinology, circadian biology, photomorphogenesis, photodamage and photoprotection, and photochemistry and photophysics. Techniques such as spectroscopy, fluorometry, microscopy, and molecular biology are used to study light absorption, signaling, and responses.

Applications span agriculture, where light quality affects crop growth and flowering, medicine and dermatology (phototherapy, photodynamic therapy), and environmental science (light-driven processes in ecosystems, remote sensing). The field also informs the development of solar-energy–related technologies and artificial photosynthesis.