title: Metabolic engineering of the mevalonate and non-mevalonate isopentenyl diphosphate-forming pathways for the production of health-promoting isoprenoids in tomato.
abstract: The genetic manipulation of both the mevalonic acid (MVA) and methylerythritol-4-phosphate (MEP) pathways, leading to the formation of isopentenyl diphosphate (IPP), has been achieved in tomato using 3-hydroxymethylglutaryl CoA (hmgr-1) and 1-deoxy-d-xylulose-5-phosphate synthase (dxs) genes, respectively. Transgenic plants containing an additional hmgr-1 from Arabidopsis thaliana, under the control of the cauliflower mosaic virus (CaMV) 35S constitutive promoter, contained elevated phytosterols (up to 2.4-fold), but IPP-derived isoprenoids in the plastid were unaltered. Transgenic lines containing a bacterial dxs targeted to the plastid with the tomato dxs transit sequence resulted in an increased carotenoid content (1.6-fold), which was inherited in the next generation. Phytoene and beta-carotene exhibited the greatest increases (2.4- and 2.2-fold, respectively). Extra-plastidic isoprenoids were unaffected in these lines. These data are discussed with respect to the regulation, compartmentalization and manipulation of isoprenoid biosynthetic pathways and their relevance to plant biotechnology.
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK.
authors.forename: Eugenia M A
authors.initials: EM
authors.lastname: Enfissi
authors.forename: Paul D
authors.initials: PD
authors.lastname: Fraser
authors.forename: Luisa-Maria
authors.initials: LM
authors.lastname: Lois
authors.forename: Albert
authors.initials: A
authors.lastname: Boronat
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schuch
authors.forename: Peter M
authors.initials: PM
authors.lastname: Bramley