Conservation and Diversification of Floral Homeotic MADS-box Genes in Eustoma grandiflorum

The MADS-box gene family is one of the largest transcription factor gene families in plants and is necessary at various developmental stages. Many studies on flower development show that especially MIKCc-type MADS-box genes are essential for proper floral organ development. We identified and characterized MIKCc-type MADS-box genes expressed in Eustoma grandiflorum flowers. Twenty-three genes were identified and grouped into 10 clades, which were characterized by conserved specific motifs. Phylogenetic analysis indicated the diversification of AG/PLE, AP3/DEF, PI/GLO, and SEP clades and the occurrence of recent gene duplication events. The floral organ-specific expression patterns were partly diversified within the gene members of AP3/DEF and SEP clades, while they were conserved in AG/PLE and PI/GLO clades. These results suggest that genes with conserved expression as well as those with diversified expression contribute to specifying floral organ identity in E. grandiflorum.