Chrysanthemum Cm HSFA 4 gene positively regulates salt stress tolerance in transgenic chrysanthemum

Summary Salinity‐induced Na + toxicity and oxidative stress hamper plant growth. Here, we showed that expression of the chrysanthemum Cm HSFA 4 , a homologue of the heat‐shock factor At HSFA 4a , is inducible by salt and localizes to the nucleus. It is a transcription activator binding with HSE . Chrysanthemum overexpressing Cm HSFA 4 displayed enhanced salinity tolerance by limiting Na + accumulation while maintaining K + concentration, which is consistent with the up‐regulation of ion transporters Cm SOS 1 and Cm HKT 2 . Additionally, the transgenic plants reduced H 2 O 2 and O 2 ∙− accumulation under salinity, which could be due to up‐regulation of ROS scavenger activities such as SOD , APX and CAT as well as Cm HSP 70 , Cm HSP 90 . Together, these results suggest that Cm HSFA 4 conferred salinity tolerance in chrysanthemum as a consequence of Na + /K + ion and ROS homeostasis.