Characterization of the maize gene encoding a conserved WD40 protein

Hernandez, Julia M. (1), Pizzirusso, M. (2), Sosa, G.M. (1), and Grotewold E. (1)

(1) The Ohio State University. Department of Plant Biology and Plant Biotechnology Center, Columbus, OH, and (2) Dartmouth College, Hanover, NH.

Flavonoid Biosynthesis is regulated by Myb-domain proteins, or by their interaction with factors containing bHLH motifs. In maize, phlobaphene biosynthesis is controlled by the Myb-domain protein P, and anthocyanin biosynthesis is controlled by the interaction of the Myb-domain protein C1with the bHLH protein R. While the need of C1 and R for anthocyanin accumulation is clear, they appear not to be sufficient to activate expression of promoters containing C1 binding sites in yeast, suggesting that other factors are needed. In Petunia, mutations in the an11 gene abolish anthocyanin accumulation in the corolla. The an11 gene encodes a cytoplasmatic WD40 protein, and loss of an11 function can be complemented by overexpression of the Petunia C1 protein, AN2. We cloned and characterized a maize gene that encodes a protein with a high level of identity to AN11, and which belongs to a group of genes encoding very related WD40 proteins. Its expression pattern is similar to that of AN11, and its map position suggests a possible role in the control of anthocyanin biosynthesis. Preliminary experiments aimed at understanding by which mechanisms it may control gene expression will be discussed.