SUMMARY
The genes of the MADS-Box family have many plant growth, development and reproduction roles. To facilitate flowering in Arabidopsis, the MADS-Box family SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) genes incorporate environmental signals. In this study, FBP21 gene was isolated from young flower bud of Petunia axillaris through PCR followed by gel elution and cloning in pGEM-T easy vector. Confirmed clones were sequenced, obtained a coding sequence (CDS) of 657bp, and coded a deduced protein of 218 amino acid residues. Sequence analysis showed that putative FBP21 protein harbors highly conserved MADS-box domain, K-box domain and SOC1-motif. Based on sequence analysis, FBP21 shows the highest sequence similarity to Nicotiana tabacum SOC1 protein (89.44% identity) and the lowest sequence similarity with Oryza sativa MADS50 (61% identity). Phylogenetic analysis revealed that FBP21 was a member of the SOC1 proteins and was the most closely related to SOC1 from Nicotiana tabacum. FBP21 gene expression was analyzed in various stages of flower and leaf of Petunia, showed that FBP21 gene was highly expressed in young floral buds, indicating that FBP21 is involved in the induction of ?ower initiation in Petunia. Characterization of FBP21 gene through various bioinformatics software’s viz. BioEdit, Mega7, ExPASy Protparam tool, PHYRE2 server, RAMPAGE and ProSA Web Server. Functions of FBP21 gene was predicted and analyzed by Protein-Protein interaction (PPI) network of FBP21 protein with other family proteins from Arabidopsis. These findings will help in further MADS-Box gene family study genes in various plant species and broaden our area of understanding of flower development.