Transcription factor that binds specifically to a 5'-AA[AG]G-3' consensus core sequence (By similarity). Regulates a photoperiodic flowering response. Transcriptional repressor of 'CONSTANS' expression. The stability of CDF2 is controlled by 'GIGANTEA' and redundantly by ADO3, ADO2 and/or ADO1. Interacts with ADO2 (via kelch repeats) and ADO3 (via kelch repeats). Expressed in the vasculature of cotyledons and hypocotyls, leaves and roots. Circadian-regulation. Highly expressed at the beginning of the light period, then decreases, reaching a minimum between 16 and 29 hours after dawn before rising again at the end of the day. Regulated at the protein level by ADO3 and GI pos-transcriptionally. Early flowering.