DgbZIP3 interacts with DgbZIP2 to increase the expression of for cold stress tolerance in chrysanthemum.

The bZIP transcription factor plays a very important role in abiotic stresses, e.g. drought, salt, and low-temperature stress, but the mechanism of action at low temperature is still unclear. In this study, overexpression of led to increased tolerance of chrysanthemum ( Ramat.) to cold stress, whereas antisense suppression of resulted in decreased tolerance. Electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation (ChIP), luciferase complementary imaging analysis (LCI), and dual-luciferase reporter gene detection (DLA) experiments indicated that DgbZIP3 directly bound to the promoter of and activated its expression. DgbZIP2 was identified as a DgbZIP3-interacting protein using yeast two-hybrid, co-immunoprecipitation, LCI, and bimolecular fluorescence complementation assays. Overexpression of led to increased tolerance of chrysanthemum to cold stress, whereas antisense suppression of resulted in decreased tolerance. A ChIP-qPCR experiment showed that DgbZIP2 was highly enriched in the promoter of , while DLA, EMSA, and LCI experiments further showed that DgbZIP2 could not directly regulate the expression of . The above results show that DgbZIP3 interacts with DgbZIP2 to regulate the expression of to promote an increase in peroxidase activity, thereby regulating the balance of reactive oxygen species and improving the tolerance of chrysanthemum to low-temperature stress.