Soil salinization is a major environmental stress limiting plant growth and development, affecting crop yields worldwide. We investigated the role of AtDPBF3, encoding a key member of the ABI5 subfamily, in the response to salt stress. The AtDPBF3 mutant (dpbf3) was significantly more sensitive to salt stress compared with wild type. Compared with leaves of salt-stressed wild type, those of salt-stressed dpbf3 exhibited severe decreases in chlorophyll content and photochemical efficiency (Fv/Fm), and disrupted ion homeostasis (higher Na