USE OF A DS CHROMOSOME-BREAKING ELEMENT TO EXAMINE MAIZE VP5 EXPRESSION

To determine the localization of Vp5 expression in maize, and to further characterize vp5 mutations in kernels and in other parts of the plant, a genetic technique was utilized to generate mosaic tissues. In particular, advantage is taken of a feature of the Activator (Ac)-Dissociation (Ds) controlling elements of maize to cause chromosome breakage, allowing phenotypic observation of the lethal vp5 allele throughout the maize plant. Mosaic tissues result from chromosome breakage at the site of the Ds element and subsequent unmasking of a recessive vp5 allele. The appearance of sectors in both endosperm and leaf tissue indicates that the Vp5 product behaves in a cell-autonomous fashion. Spectrophotometric analysis of leaf-sector pigments supports this observation.