Required for salt tolerance and sodium (Na) homeostasis after salt stress. Together with BHLH148/RITF1, regulates the transcription of several genes involved in the detoxification of reactive oxygen species (ROS) generated by salt (NaCl) stress. Binds calcium. Interacts with BHLH148/RITF1. Expressed ubiquitously at high levels, including in guard cells. Slightly induced by salt (NaCl) stress. Defective embryo arrested at cotyledon stage (PubMed:15266054). Hypersensitivity to salt (NaCl) stress leading to reduced roots and shoots growth and altered germination, and associated with altered sodium (Na) homeostasis and over-accumulation of reactive oxygen species (ROS). Hypersensitivity to hydrogen peroxide H(2)O(2) and methyl viologen (MV) (PubMed:24009530).