ABSTRACT
In flowering plants, floral homeotic MADS-box genes, which constitute a large multigene family, play important roles in the specification of floral organs as defined by the ABCDE model. In this study, a MADS-box gene, ZjMADS1, was isolated and characterized from the marine angiosperm Zostera japonica. The predicted length of the ZjMADS1 protein was 246 amino acids (AA), and the AA sequence was most similar to those of the SEPALLATA (SEP) subfamily, corresponding to E-function genes. Southern blot analysis suggested the presence of two SEP3-like genes in the Z. japonica genome. ZjMADS1 mRNA levels were extremely high in the spadices, regardless of the developmental stage, compared to other organs from the reproductive and vegetative shoots. These results suggest that the ZjMADS1 gene may be involved in spadix development in Z. japonica and act as an E-function gene in floral organ development in marine angiosperms.