Functional conservation and diversity of phytochrome B and its potential applications in crop improvement

Phytochrome, first identified in the 1950s as a photoreceptor that senses red and far-red light, plays a crucial role in various aspects of plant growth and development. Numerous recent studies have revealed that phytochrome B (phyB) functions as both a photoreceptor and a thermosensor, integrating environmental light and temperature signals with internal hormonal, developmental, and metabolic cues to coordinate diverse cellular responses. As a core regulator, phyB has become one of the most extensively studied genes in the model plant Arabidopsis thaliana. More recently, research on phyB has extended to major staple crops and vegetables, including maize, rice, wheat, tomato, and cucumber, in which it modulates critical agronomic traits such as plant architecture, flowering time, density tolerance, and yield. This review summarizes recent advances in phyB research, examines phyB conservation and diversity across species, and explores future prospects for using this information to develop innovative breeding strategies for crop improvement.