The main aim of this thesis is understanding the molecular regulation of flowering time in Arabidopsis thaliana. More specifically, we focus on of key regulatory genes of flowering that integrate several internal and external flowering signals and examine in detail how they are regulated at the transcriptional and post-transcriptional level. Many of the key regulatory genes encode transcription factors (TFs), which are often functioning in larger protein complexes and are part of complex gene regulatory network. This thesis focuses on two important regulators that are MADS-domain TFs, SHORT VEGETATIVE PHASE (SVP) and SUPPERESSOR OF OVEREXPRESSION of CONSTANCE 1 (SOC1) and we studied the protein-protein interactions, chromosomal interactions and TF-DNA interactions, all connections that are part of the gene regulatory networks involved in flowering time control.