PHYE

PHYE is the gene encoding phytochrome E, a plant photoreceptor found in Arabidopsis thaliana and related species. As a member of the phytochrome family, PHYE senses red and far-red light and acts as a molecular switch that modulates plant development in response to the light environment. Phytochromes exist in two interconvertible forms: Pr (inactive) and Pfr (active). Upon absorption of red or far-red light, PHYE shifts between these forms, accumulates in the nucleus, and influences transcription by affecting signaling components and interacting factors.

In Arabidopsis, PHYE is expressed across tissues with levels that vary under different light conditions. The PHYE protein localizes to both the cytoplasm and nucleus and can form photobodies in the nucleus after light activation. Genetic analyses show that phye mutants have relatively subtle phenotypes under many conditions, but reveal functional redundancy with other phytochromes, particularly PHYB and PHYA. In higher-order mutant backgrounds, loss of PHYE can modify shade avoidance, de-etiolation, and other light-dependent responses, indicating that PHYE contributes to the overall light-sensing network rather than acting as a sole determinant.

Across flowering plants, PHYE homologs are present and often retain red/far-red sensing roles, reflecting the conserved nature of the phytochrome signaling system. Research on PHYE informs understanding of photomorphogenesis, light adaptation, and potential crop improvement strategies.