ClustalW sequence alignment and phylogenetic analysis of ZmGA3ox1 and ZmGA3ox2 with related GA3oxs. Amino acid alignment (A) and a phylogenetic tree (B) showing the relationships among maize ZmGA3ox2 (AFS50158), ZmGA3ox1 (AFS50160), Arabidopsis AtGA3ox1 (NP_173008), rice OsGA3ox1 (BAB62073) and OsGA3ox2 (BAB17075), pea PsGA3ox1 (AAB65829), barley HvGA3ox2 (AAT49061), B. distachyon BdGA3ox2 (XP_003569638), and wheat TaGA3ox2 (Q3I409). Mutations (deletions or insertions) in later characterized d1 alleles were marked (see Fig. 4). The highly conserved ferrous iron ligand binding residues for 2-oxoglutarate-dependent dioxygenases are marked as circles.