Biosynthesis of isoprenoid precursors in arabidopsis

Abstract

Isoprenoids are the most functionally and structurally diverse group of plant metabolites reported to date. Many of them participate in essential processes, like respiration (ubiquinone), photosynthesis (carotenoids, chlorophylls, plastoquinone), and regulation of growth and development (cytokinins, brassinosteroids, gibberellins, abscisic acid). However, most plant isoprenoids are considered as secondary metabolites and play key roles in mediating the interactions of plants with their environment. Some plant isoprenoids also have biotechnological interest. Despite their structural and functional diversity, all isoprenoids derive from the same five-carbon precursors, isopentenyl diphosphate (IPP) and its isomer dimethylallyl diphosphate (DMAPP). Plants contain two pathways for the synthesis of IPP and DMAPP: the mevalonate pathway (located in the cytosol/endoplasmic reticulum) and the methylerythritol 4-phosphate pathway (located in the plastids). A limited exchange of IPP and/or prenyl diphosphates is known to take place between these compartments in plant cells. In recent years, the use of the model plant Arabidopsis thaliana in genetic and biochemical approaches has allowed the identification of all the genes and enzymes from both pathways and has accelerated the flow of information on their regulation. A major challenge now is to understand how the ­production of common isoprenoid precursors in different subcellular ­locations conveys the information required to coordinate the fluxes of the two pathways. Here we review the current knowledge on these matters deduced mainly from work carried out in Arabidopsis.