Transcription activator that binds DNA to the C-box-like motif (5'-TGCTGACGTCA-3'), ABRE elements, G-box-like motif (5'-CCACGTGGCC-3'), DOF (5'-AAAG-3'), I-box (5'-GATAA-3'), BS1 (5'-AGCGGG-3'), MY3 (5'-CGACG-3'), 5'-CAGTGCGC-3' and 5'-ACTCAT-3' sequence in target gene promoters. DNA-binding and subsequent transcription activation is triggered by heterodimerization with other bZIP proteins (e.g. BZIP1, BZIP10 and BZIP25). Promotes POX1/PRODH1 expression in response to hypoosmolarity stress. Transcriptional activator of seed maturation (MAT) genes (e.g. AT2S2), including seed storage protein (SSP) and late embryogenesis abundant (LEA) genes. Activated by low energy stress both by transcriptional and post-transcriptional mechanisms. Promotes dark-induced senescence and participates in the transcriptional reprogramming of amino acid metabolism during the dark-induced starvation response, especially when heterodimerized with BZIP1, by triggering accumulation of specific proteins including ASN1 and POX1/PRODH1