The coordinate expression of genes whose products act jointly in a biochemical pathway is a focal point of regulatory biology in many organisms. The objective of the proposed research is to characterize cis- and trans-acting factors that control the transcriptional expression of several genes in the biosynthetic pathway for anthocyanin pigments in maize. Anthocyanin synthesis requires the products of both structural and regulatory genes. The results of genetic and molecular analyses implicate two of the regulatory genes, C1 (Colored aleurone-1) and Pl (Purple plant) as positive trans-activators that perform analogous regulatory functions in distinct tissues to control pigmentationin the kernel and the plant, respectively. This proposal is aimed at evaluating the molecular interactions between C1 or P1 and the genes whose transcription they control. Nuclear extracts from maize tissues will be used in DNase I footprinting experiments to identify cis-acting elements in cloned target genes. Both in vitro and in vivo assays will be performed to determine if the C1 and P1 gene products are capable of specifically binding target elements and/or activating transcription. Molecular genetic approaches will be used to explore the regulation of C1 and P1 themselves with the goal of identifying other factors that mediate the tissue-specific expression of these regulatory genes. The pathway for anthocyanin biosynthesis in maize has been the focus of many of the extensive genetic studies in corn, primariy because of the ease of detecting color mutants. This study will deepen our insight into how genes encoding structural protein are regulated in their expression in plants.
