Genome-wide identification of MADS-box gene family in sacred lotus (Nelumbo nucifera) identifies a SEPALLATA homolog gene involved in floral development

BACKGROUND: Sacred lotus (Nelumbo nucifera) is a vital perennial aquatic ornamental plant. Its flower shape determines the horticultural and ornamental values. However, the mechanisms underlying lotus flower development are still elusive. MADS-box transcription factors are crucial in various features of plant development, especially in floral organogenesis and specification. It is still unknown how the MADS-box transcription factors regulate the floral organogenesis in lotus. RESULTS: To obtain a comprehensive insight into the functions of MADS-box genes in sacred lotus flower development, we systematically characterized members of this gene family based on the available genome information. A total of 44 MADS-box genes were identified, of which 16 type I and 28 type II genes were categorized based on the phylogenetic analysis. Furthermore, the structure of MADS-box genes and their expressional patterns were also systematically analyzed. Additionally, subcellular localization analysis showed that they are mainly localized in the nucleus, of which a SEPALLATA3 (SEP3) homolog NnMADS14 was proven to be involved in the floral organogenesis. CONCLUSION: These results provide some fundamental information about the MADS-box gene family and their functions, which might be helpful in not only understanding the mechanisms of floral organogenesis but also breeding of high ornamental value cultivars in lotus. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12870-020-02712-w.