Transcriptional regulator that specifically binds 5'-GATA-3' or 5'-GAT-3' motifs within gene promoters (PubMed:22102866, PubMed:25077795). Involved in the modulation of chloroplast development, growth and division in a cytokinin-dependent manner (PubMed:22102866, PubMed:22811435). Repressor of the gibberellic acid (GA) signaling pathway that represses flowering and modulates greening, in a SOC1-dependent manner (PubMed:20844019, PubMed:23739688, PubMed:25077795). Prevents the accumulation of SOC1 during flowering (PubMed:23739688). Promotes chlorophyll biosynthesis throughout the plant, by regulating chlorophyll biosynthetic genes (e.g. HEMA1 and GUN4) and chloroplast localized glutamate synthase (e.g. GLU1) (PubMed:18417639, PubMed:20844019, PubMed:22102866, PubMed:23878229, PubMed:25077795). Involved in the regulation of sugar-sensing genes (e.g. HXK1, HXK2, STP13 and PLT6) (PubMed:18417639). Regulator of germination, senescence, elongation growth and flowering time (PubMed:20844019, PubMed:22102866, PubMed:23878229). Influences also leaf starch content (PubMed:22102866). Interacts with SNL1 (PubMed:19962994). Forms heterodimers with GATA18 (PubMed:23335616). Expressed predominantly in leaves, and barely in stems, flowers and siliques. First observed in the inflorescence meristem (IM) and young flower buds (PubMed:23335616). Detected throughout the floral bud. In young flowers, restricted to the inner whorls, specifically the petals, stamens, and carpels (PubMed:18417639, PubMed:23335616). In older flowers, present in the petals, stamen filaments and carpels, with weaker expression in the anthers of the stamens (PubMed:18417639). Observed in anther locules, vascular strands, and ovules (PubMed:23335616). During imbibition, expressed in the endosperm, especially at the time of testa rupture. Later restricted to the embryonic root (PubMed:20844019). In mature embryos, observed in the cotyledons and hypocotyl. In young seedlings, mostly expressed in shoot tissues, including the tip, circumference, and vasculature of the cotyledons, the emerging leaves, the meristematic region, and the basal part of the hypocotyl, and, at low levels, in the primary roots. In older seedlings, accumulates in the green shoot tissues (PubMed:22811435). Activated by gibberellic acid (GA) (PubMed:20844019). Negatively regulated by AP3/PI (PubMed:18417639). Strong accumulation during cold imbibition of nondormant seeds, but not at warm temperatures. Regulated by PIF transcription factors (PubMed:20844019). Induced by cytokinin (e.g. benzyladenine) (PubMed:22811435). Repressed by HAN (PubMed:23335616). Inhibited by SOC1 (PubMed:23739688). Down-regulated by auxin (2,4D) and auxin response factors (e.g. ARF2 and ARF7) (PubMed:23878229). Pale green leaves and reduced chlorophyll levels associated with altered regulation of sugar-sensing genes (e.g. HXK1, HXK2, STP13 and PLT6) (PubMed:18417639, PubMed:22102866, PubMed:22811435). Reduced chloroplast size (PubMed:22811435). Faster seed germination. Early flowering. Increased leaves size (PubMed:20844019, PubMed:22102866). Reduced gibberellic acid (GA) levels due to increased GA turnover and associated with reduced expression of GA-anabolizing enzymes (e.g. GA3OX1) but increased expression of GA-catabolizing enzymes (e.g. GA2OX2) (PubMed:20844019). Small seeds with deformed seed coats (PubMed:22102866). The double mutant gnc cga1, lacking both GATA22 and GATA21, exhibits reduced sensitivity to cytokinin (e.g. benzyladenine) toward chloroplasts growth (PubMed:22811435). May be due to a competing acceptor splice site. Belongs to the type IV zinc-finger family. Class B subfamily.