Flavonoids and related phenolic compounds produced in the first internode of Sorghum vulgare Pers. in darkness and in light.

Knowledge of C15 intermediates in the biosynthesis of anthocyanins is scanty or controversial. Recently, chalcones (7) and leucoanthocyanins (2) have been postulated as intermediates from evidence based on kinetic studies and isotope experiments. Downs and Siegelman (3) have studied the photocontrol of anthocyanin synthesis in seedlings of Sorghum vulgare. The anthocyanin has been identified as an acylated cyanidin-3-glucoside, and possible C9 precursors of this pigment have been studied with isotope techniques (1). Since the first internode (mesocotyl) of Sorghum can be easily grown in the dark and forms large amounts of the red anthocyanin only in the light, this material was examined in hopes that intermediates in anthocyanin biosynthesis might be accumulated under appropriate conditions. It was necessary first to know what phenolic compounds were present in conmpletely dark-grown internodes and what changes took place upon illumination.