Red beet as a model system for studying vacuolar transport of primary and secondary metabolites

Abstract

The vacuole in a plant cell is a highly dynamic structure with important functions in maintaining the balance between synthesis, sequestration, storage and distribution of minerals/metabolites, precisely monitoring the fl ow in and out as well as biochemical conversions occurring in the cell. Red beet has served as a model system for studies of several vacuolar functions and made important contributions to our understanding of metabolite transporters located in the vacuolar membrane. Thus, here, we give an overview of the current progress made on unravelling transport of secondary metabolites, solutes and ions with special emphasis on contributions from red beets. Red beet is an important source of the two metabolites betalains and folates. Whereas the biosynthesis and accumulation of these metabolites have been studied in different systems, the transport processes have not been fully understood. Thus, red beet serves as a model to study not only important biosynthetic steps and the enzymes involved in betalain and folate synthesis, but also for unravelling transport and cellular signalling processes. Knowledge about red beet primary and secondary metabolism can thus provide further insight into the possible roles of various transporters, which may then be applied for regulation of the biosynthesis and recovery of these metabolites.