DNA sequence elements in the 346-kb contig. The entire 346-kb sequence is represented as a green bar with size scale below. Above the bar, the 22-kD α zein genes are shown in relation to other sequence features. Color-coded bars visualize the position of the various predicted genes, retroelements, and the 22-kD α zein genes. A key for these is provided. The truncation of azs22;3 and the insertion inazs22;7 are marked by the vertical lines through the small circles. The 3′ terminal duplicated sequence is marked with boxes. The portion depicting the 168-kb zein gene cluster is marked by a bidirectional arrow above. Within this region, the two subclusters are marked by bidirectional arrows as well. In addition, upward dotted arrows indicate from left to right the positions of the direct repeats, DR1, DR2, and DR3 that flank the recent amplified genes.