Regulation of Cat1 gene expression in the scutellum of maize during early sporophytic development.

A regulatory element has been identified in maize that appears to exert an effect specifically on Cat1 gene expression in the scutellum of maize during early sporophytic development. Cat1 encodes CAT-1 catalase, one of two forms of catalase expressed in the scutellum during this developmental time period. Density-labeling experiments indicate that the regulatory element influences the overall levels of CAT-1 protein synthesis in the scutellum but has no effect on CAT-2 protein synthesis. Immunoprecipitation experiments of in vitro translation products suggest that this element has an effect on the level of translatable Cat1 mRNA associated with the scutellar polysomes. The element exhibits additive inheritance and is tissue and time specific in its action. This element, therefore, meets all the criteria of a regulatory gene and has been designated Car2. The element acts to regulate the temporal expression of the Cat1 structural locus in maize.