Maximum likelihood rooted tree of 39 Arabidopsis , 6 peach and 48 poplar MIKCC-type MADS-box genes. The tree was constructed using nucleotide sequences and a GTR+I+G evolution model. The AGL28 and PtMADS63 sequences were used as outgroups. The numbers at each interior branch indicate bootstrap support of 1000 replicates. Branches with less than 50% bootstrap support are collapsed. Branch lengths are proportional to the number of nucleotide changes.