Membrane transport of secondary metabolites in plants.

Abstract

AbstractHigher plants produce a large number of secondary metabolites, such as alkaloids, terpenoids, phenolic compounds, and many further compounds have combined structures of those groups. They are often accumulated in particular sink organs, and some are translocated from source cells via long distance transport. The membrane transport of plant secondary metabolites is a newly developing research area. Recent progress in genome sequencing projects and expressed sequence tag (EST) databases has revealed that many genes coding for transporters and channels exist in the plant genome. Studies on phenotype analyses of many mutants by various criteria have identified transporter molecules responsible for the membrane transport of plant secondary metabolites. Characterizations of such transporter genes have clarified that the membrane transport for each secondary metabolite is fairly specific and highly regulated. Not only genes involved in the biosynthesis of secondary metabolites but also genes relevant to their transport will be important for the high accumulation of those metabolites. Hence, knowledge about the membrane transport mechanism is necessary for systematic metabolic engineering aimed at increasing the productivity of valuable secondary metabolites in planta.