Transcription factor OsDOF1 enhances cold-stress tolerance potentially through interactions with OsICE1 and its target genes in rice (Oryza sativa L.)

Rice plants are generally sensitive to cold temperatures, which adversely affect their yield. Japonica rice, a major subspecies of Oryza sativa L. (Asian cultivated rice), exhibits cold tolerance. Recently, we identified that the plant-specific transcription factor DNA binding with one finger 1 (Dof1) was associated with the cold resistance of Japonica rice. The purpose of this study was to delineate the role of the OsDof1 gene in cold-stress tolerance and its potential molecular pathways. Two japonica rice varieties, including the cold-resistant line LD5 and the cold-sensitive line LJ11, were used. The protein-protein interactions were determined by yeast two-hybrid (Y2H), tag-based pull-down, and bimolecular fluorescence complementation (BiFC) assays. Truncated DsDOF1 protein was identified in LJ11 as a consequence of a point mutation, and OsDOF1-T failed to be transported into the nucleus. Furthermore, OsDREB1B, OsDREB2A, OsNF-YC, OsLEA3, OsRAB16A, OsLIP9, OsNCED3, OsABI2, OsMYBS3, and OsBS3R-2 were differentially expressed in OsDof1-overexpressing transgenic versus wild-type rice lines. Notably, OsICE1 was found to be the target protein of OsDOF1, and subsequent Y2H, BiFC, and tag-based pull-down assays showed a direct interaction between the two proteins. In conclusion, OsDOF1 exerts a critical role in cold tolerance potentially through direct interactions with OsICE1 and its target genes in rice. These findings may help to better understand the molecular basis of rice adaptation to cold stress, and OsDof1 could be a target gene in the molecular breeding of rice for better adaptation to a cold-climate environment, which might eventually improve the yield of rice.