The developmental expression of the maize regulatory gene Hopi determines germination-dependent anthocyanin accumulation

The Hopi gene is a member of the maize r1 gene family. By genetic and molec ular analyses eve report that Hopi consists of a single gene residing on ch romosome 10 similar to 4.5 cM distal to r1. Hopi conditions anthocyanin dep osition in aleurone, scutellum, pericarp, root, mesocotyl, leaves, and anth ers, thus representing one of the broadest specifications of pigmentation p attern reported to dare of all the r1 genes. A unique feature of the Hopi g ene is that seeds are completely devoid of pigment at maturity but show a p hotoinducible germination-dependent anthocyanin accumulation in aleurone an d scutellum. Our analysis has shown that the Hopi transcript is not present in scutellum of developing seeds but is induced only upon germination and that the simultaneous presence of both C1 and Hopi mRNAs is necessary to ac hieve A1 activation in scutella. We conclude that the expression pattern of the Hopi gene accounts for the germination-dependent anthocyanin synthesis in scutella, whereas the developmental competence of germinating seeds to induce anthocyanin production in scutella results from the combination of t he light-inducible expression of C1 and the developmentally regulated expre ssion of the Hopi gene.