Biochemical and morphological determination of flower color in Gentianaceae

Abstract

Since Charles Darwin wrote his excellent book about flower-color polymorphism within the same species (Darwin 1877), studies on plant dyes have become one of the most popular research subjects in botany. After nearly 200 years of investigation into the biochemistry and physiological factors involved, the pathway leading to the accumulation of pigments in petals is well understood. Flavonoids are the major pigments that confer flower color, and their biosynthesis is now characterized at the genetic and enzymatic level in many decorative plants, including Eustoma, Carnation, Petunia, and Snapdragon. This chapter summarizes the current status of all the key biosynthesis steps and secondary modification of the pigments and co-pigments, which are responsible for the diversity of color patterns observed in Gentian species. A brief overview is also given about the cellular and subcellular localization of plant pigments in order to facilitate understanding of the molecular basis of color patterning in flowers. More specifically, anthocyanin vacuolar inclusion structures (AVIs) have been shown to affect the final color by accumulating high concentrations of anthocyanins. The shape and morphology of petal epidermal cells may play an important role in determining flower color in Gentianaceae.