DOF is a novel family of plant-specific proteins that share a unique and highly conserved DNA binding domain with one CX2CX21CX2C zinc finger motif. In this study, the Osdof28 gene, which codes a characteristic amino acid sequence of the DOF transcription factor family, was screened from rice (Oryza sativa japonica) using a yeast one-hybrid assay. Great amounts of the Osdof28 transcripts were found to accumulate in stems and leaves, with less in the roots, and no detectable transcription found in the germs. Osdof28 can be induced by salicylic acid and INA, which suggests that it may be related to the plant systemic acquired resistance (SAR). The relationship was confirmed through biological induction of SAR using Xanthomonascampestrispv. oryzae, with more expression of Osdof28 observed in the systemic tissues after infection.
The OsDREB1 gene from rice encodes a transcription factor belonging to the DREBP transcription factor subfamily. Many DREBP transcription factors regulate gene expression in response to drought, high-salt, and cold stresses by binding specifically to the dehydration-responsive element (DRE). DRE-binding proteins, such as CBF1, DREB1A, and DREB2A, have been cloned from Arabidopsis thaliana and have been proved to play an important role in stress response of Arabidopsis and several other plants. In this study, the OsDREB1 gene was transferred to tobacco plants by the Agrobacterium-mediated transfer method, and 16 transgenic plants were identified. PCR analysis demonstrates that the foreign genes have been integrated into the tobacco genome. Results of freezing stress experiments indicate that the transgenic plants have enhanced cold tolerance.
