Figure 1.

Phylogenetic tree showing the relationships between a subset of MIKC-type MADS-domain proteins known. The tree was constructed by using the “MIK-domain” sequences and the neighbor-joining algorithm. Genus names of species from which the respective genes were isolated are given in parentheses after the protein names. Gnetum proteins are indicated by inverted boxes, and genes from non-gnetalean gymnosperms are indicated by shaded boxes. Proteins from ferns are highlighted by open boxes. Proteins that are not boxed have been derived from angiosperm gene sequences. The numbers next to some nodes give bootstrap percentages, which are shown only for relevant nodes and those defining gene subfamilies. Subfamilies, which generally represent monophyletic gene clades (17, 23), are labeled by brackets at the right margin.