Unusual phenotypes are caused by the Ds transposable element

New phenotypes in corn are produced through the movement of the Ds transposable element on chromosome 9. (a) A chromosome fragment is lost through breakage at the Ds locus. Recessive alleles on the homologous chromosome are expressed, producing the colorless sector in the kernel. (b) Insertion of Ds in the C gene (top) creates colorless corn-kernel cells. Excision of Ds from the C gene through the action of Ac in cells and their mitotic descendants allows color to be expressed again, producing the spotted phenotype.