Plays a pivotal role in the control of morphogenesis of shoot organs by negatively regulating the expression of boundary-specific genes such as CUC genes, probably through the induction of miRNA (e.g. miR164). Participates in ovule develpment (PubMed:25378179). Participates in ovule develpment (PubMed:25378179). Promotes light-regulated transcription of CHS, CAB, HYH and HY5. Regulates positively photomorphogenesis (e.g. hypocotyl elongation inhibition and cotyledon opening in response to blue light) (PubMed:26596765). Interacts with SPL (PubMed:25378179, PubMed:25527103). Interacts with CRY1 (PubMed:26596765). Expressed in cotyledons, particularly in the vascular region, in leaves, roots, buds, flowers and immature siliques. During flower development, first observed throughout the floral meristem. Later expressed in rapidly growing floral primordia. Detected to a lower extent in vegetative primordia. During flower development, first observed throughout the floral meristem. Expressed during ovule development (PubMed:25378179). Repressed by the miRNA miR-JAW (PubMed:12931144). Induced by blue light. Stabilized by light but labile in darkness due to proteasome-dependent proteolysis (at protein level) (PubMed:26596765). Reduced light-mediated transcription of CHS, CAB, HYH and HY5. Impaired influence of blue light on hypocotyl elongation. Truncated N-terminus. Truncated N-terminus.