Unveiling the role of CtDREB1B from safflower: enhancing plant resistance to drought and salt

BACKGROUNDS: The DREB (dehydration-responsive element binding) transcription factor family comprises key regulators that are widely used in genetic engineering to improve plant abiotic stress tolerance. However, the functional characteristics of DREB genes in safflower (Carthamus tinctorius L.) remain largely unknown. RESULTS: In this study, a novel DREB gene designated CtDREB1B, was cloned from safflower. The full-length CDS of CtDREB1B was 600 bp, encoding a protein of 199 amino acids containing a conserved AP2 domain and belonging to the DREB A1 subgroup. Transient expression in maize protoplasts and tobacco leaves showed that CtDREB1B was localized to both the nucleus and cell membrane, and yeast assays verified its strong transcriptional activation activity. Expression pattern analysis revealed that CtDREB1B was predominantly expressed in S7 flower stage and leaves and was strongly induced by cold, drought, salt and IAA, but not by ABA and MeJA. Functional validation demonstrated that overexpression of CtDREB1B improved drought and salt tolerance in both yeast and transgenic Arabidopsis thaliana. Under drought and salt stresses, transgenic plants accumulated lower levels of reactive oxygen species (H₂O₂ and O₂⁻), exhibited higher activities of antioxidant enzymes (SOD, POD, and CAT), and showed significantly upregulated expression of core stress-responsive genes (AtABF3, AtRD29A, AtRD29B, AtNCED3, AtCOR15A, and AtSOS1). CONCLUSION: This study identifies a potential regulatory mechanism underlying plant drought and salt tolerance mediated by a nucleus- and membrane-localized DREB transcription factor, and provides a candidate gene resource and theoretical support for the molecular breeding of stress-tolerant crops.