Functional Conservation and Diversity of Phytochrome B and its Potential Applications in Crop Improvement

Phytochrome, first identified in the 1950s as a photoreceptor sensing red (R) and far-red (FR) light, plays a crucial role in various aspects of plant growth and development. Numerous recent studies have revealed that phytochrome B (phyB) functions both as 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, where it modulates critical agronomic traits such as plant architecture, flowering time, density tolerance, and yield. This review summarizes recent advances in phyB research, examines its conservation and diversity across species, and explores future prospects for applying this knowledge to develop innovative breeding strategies for crop improvement.