title: The regulation of carotenoid formation in tomato fruit.
abstract: Carotenoid biosynthesis in plants includes a complex series of desaturation/isomerisation reactions, catalyzed by four independent enzymes. In bacteria and fungi one desaturase/isomerase enzyme completes the same series of reactions. In the present study, a bacterial desaturase (crtI) from Pantoea ananatis has been overexpressed in the tangerine mutant of tomato (Solanum lycopersicon) which accumulates cis-carotene isomers in the fruit due to a defective isomerase (CRTISO) and the old gold crimson (ogc) tomato mutant, which is defective in the fruit-enhanced lycopene β-cyclase (CYCB). Comprehensive molecular and biochemical characterization of the resulting lines expressing crtI has revealed negative feedback mechanisms, acting predominantly at the level of phytoene synthase-1 (PSY1), and feed-forward mechanisms inducing cyclisation. In both cases, altered transcription appears to be the progenitor, with subsequent post-transcriptional modulation highlighting the complexity of the processes involved in modulating carotenoid homeostasis in plant tissues.
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 OEX, UK.
authors.forename: Eugenia M A
authors.initials: EM
authors.lastname: Enfissi
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 OEX, UK.
authors.forename: Marilise
authors.initials: M
authors.lastname: Nogueira
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 OEX, UK.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Bramley
authors.affiliation: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 OEX, UK.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Fraser
mesh_terms: D002338:Carotenoids / Q000378:metabolism*; D005638:Fruit / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D013729:Terpenes / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D013729:Terpenes; D002338:Carotenoids
keywords: 
  Solanum lycopersicon
  ; carotenoid; isoprenoid