Light-dependent regulation of carotenoid biosynthesis in plants

Carotenoids are colored terpenes synthesized in plants, algae and some yeasts and bacteria. In plants and algae, these lipophilic molecules exert functional roles in hormone synthesis, photosynthesis, photomorphogenesis and photoprotection. Additionally, they possess antioxidant properties and act as scavengers of reactive oxygen species. During the past decade almost all of the carotenogenic genes have been identified by molecular, genetic and biochemical approaches in the Arabidopsis thaliana model system. Carotenoid biosynthesis in plants is highly regulated, although all of the processes involved have not yet been identified. In this work, we review the mechanisms involved in the light-mediated regulation of carotenoid biosynthesis and the effect of light on the levels of expression of carotenogenic genes in higher plants. It has been shown that light induces the expression of carotenogenic genes during leaf and flower development and during fruit ripening. During these processes, photoreceptors are activated by light and translocated to the nucleus, leading to the induction of carotenogenic gene transcription. The molecular insight gained into the light-regulated expression of carotenoid genes will facilitate our understanding of the regulation of carotenoid biosynthesis. Manipulation of light signaling is also a genetic tool for altering color and nutritional value in plants, leading to the production of novel functional foods.