Transcription factor that, in opposition to HDG1, promotes cell proliferation and morphogenesis via transcriptionnal activation of meristem and cell proliferation genes, but prevents differentiation, especially during embryogenesis (PubMed:12172019, PubMed:25564655). Binds to the promoter and triggers the expression of epidermally expressed genes such as GSO1, GSO2, ACR4 and WER, and of HD-ZIP homeobox genes including PDF2, HDG1, HDG5, HDG7, HDG8, HDG11, ANL2, PDF2 and ATML1 (PubMed:25564655). Interacts with HDG1, HDG2, HDG3, HDG10, ANL2, ATML1, PDF2, HDG11 and HDG12. Mostly expressed in developing seeds. Also expressed in roots, seedlings, and siliques, and, at low levels, in leaves. Expressed in embryo during embryogenesis, first throughoutthe embryo, but later basally localized at the heart stage (PubMed:12172019, PubMed:25564655). Also present in free nuclear endosperm, but disappears once endosperm cellularization begins (PubMed:12172019). Observed in the stem cell niche and the provascular tissue of mature roots (PubMed:25564655). Was named 'Baby boom' because overexpressing transgenic plants exhibit several spontaneous somatic embryos. Belongs to the AP2/ERF transcription factor family. AP2 subfamily.