Rice OBF binding protein 4 (OsOBP4) participates in flowering and regulates salt stress tolerance in Arabidopsis

DNA-binding with one finger (DOF) transcription factors (TFs) play an important role in gene regulation for the proper growth and development of plants. Ocs-element binding factor (OBF) binding protein 4 (OBP4), an essential member of the DOF TF family, regulates flowering and abiotic stress. However, the functions of OBP4 in rice remain obscure, which limits its potential use in molecular breeding. In this study, rice OBP4 (OsOBP4) was functionally characterized and its role in flowering and abiotic stress was verified. Phylogenetic analysis revealed that OsOBP4 is homologous to OBP4 in Arabidopsis. OsOBP4 is modulated by salt, osmotic, and abscisic acid (ABA) stresses. Additionally, ectopic expression of OsOBP4 complements the phenotype of the Atobp4 mutation by enhancing root development and protecting the photosynthesis system. Under salt stress and short-day conditions, OsOBP4 regulated floral development by interacting with AGL7, the upstream component for floral meristem initiation. These results provide evidence for the role of OsOBP4 in multiple responses to salt stress and suggest that OsOBP4 could be used as a potential candidate gene to improve tolerance to salt stress.