Source to sink: regulation of carotenoid biosynthesis in plants.

Carotenoids are a diverse group of colourful pigments naturally found in plants, algae, fungi and bacteria. They play essential roles in development, photosynthesis, root-mycorrhizal interactions and the production of phytohormones, such as abscisic acid and strigolactone. Carotenoid biosynthesis is regulated throughout the life cycle of a plant with dynamic changes in composition matched to prevailing developmental requirements and in response to external environmental stimuli. There are key regulatory nodes in the pathway that control the flux of metabolites into the pathway and alter flux through the pathway. The molecular nature of the mechanisms regulating carotenoid biosynthesis, including evidence for metabolite feedback, transcription and epigenetic control as well as their accumulation, storage and degradation will be the focus of this review.