Objective To identify the Phytochrome interacting factor (PIF) gene family in Phoebe bournei and explore their functions in growth and development.

Method Bioinformatics and fluorescence quantitative PCR (qPCR) were used for genome-wide identification of the PbPIFs gene family. The study examined protein physicochemical properties, gene structure, evolutionary relationships, subcellular localization, cis-acting elements in promoters, and expression patterns under light stress.

Result Nine PbPIFs genes were identified from the P. bournei genome, all of which contained highly conserved bHLH domains as well as APA or APB domains. Subcellular localization revealed that PbPIFs proteins were exclusively localized in the nucleus. Promoter analysis showed that the upstream regions of PbPIFs harbored various cis-acting elements responsive to light, drought, low temperature, and hormones, with the highest number being ABA-responsive elements. Distince tissue-specific expression patterns were observed among PbPIFs family members. qPCR results showed that PbPIF1, PbPIF3a, PbPIF3b, and PbPIF5 were significantly downregulated under light induction, suggesting their involvement in photomorphogenesis.

Conclusion The nine PbPIFs genes indentified in P.bournei exhibit functional diversification, with different members participating in responses to light signals and abiotic stressors. These findings provide a scientific basis for further dissecting the gene functions of PIF family members and their regulatory mechanisms in environmental responses.