Molecular characterization of d1 alleles. A, DNA hybridization analysis on the d1 alleles with ZmGA3ox2 probe I. 1, B73; 2, W22; 3, d1-3286; 4, d1-6039; 5, d1-6016; 6, d1-4. B, ZmGA3ox2 gene structure and different d1 alleles. The position of probe I is indicated. Exons are boxes. Shaded boxes are translated regions, and empty boxes are 5′- or 3′-untranslated regions. Introns and noncoding regions are shown as black lines. A Copia-like element (accession no. JX307642) was inserted at position 69 of the d1-3286 allele. One-base C was deleted at position 399 of the d1-6039 allele. A 487-bp fragment was deleted in the d1-4 allele. A 2,301-bp fragment was deleted in the d1-6016 allele.