title: Increased Nicotiana tabacum fitness through positive regulation of carotenoid, gibberellin and chlorophyll pathways promoted by Daucus carota lycopene β-cyclase (Dclcyb1) expression.
abstract: Carotenoids, chlorophylls and gibberellins are derived from the common precursor geranylgeranyl diphosphate (GGPP). One of the enzymes in carotenoid biosynthesis is lycopene β-cyclase (LCYB) that catalyzes the conversion of lycopene into β-carotene. In carrot, Dclcyb1 is essential for carotenoid synthesis in the whole plant. Here we show that when expressed in tobacco, increments in total carotenoids, β-carotene and chlorophyll levels occur. Furthermore, photosynthetic efficiency is enhanced in transgenic lines. Interestingly, and contrary to previous observations where overexpression of a carotenogenic gene resulted in the inhibition of the synthesis of gibberellins, we found raised levels of active GA4 and the concommitant increases in plant height, leaf size and whole plant biomass, as well as an early flowering phenotype. Moreover, a significant increase in the expression of the key carotenogenic genes, Ntpsy1, Ntpsy2 and Ntlcyb, as well as those involved in the synthesis of chlorophyll (Ntchl), gibberellin (Ntga20ox, Ntcps and Ntks) and isoprenoid precursors (Ntdxs2 and Ntggpps) was observed. These results indicate that the expression of Dclcyb1 induces a positive feedback affecting the expression of isoprenoid gene precursors and genes involved in carotenoid, gibberellin and chlorophyll pathways leading to an enhancement in fitness measured as biomass, photosynthetic efficiency and carotenoid/chlorophyll composition.
authors.affiliation: Centro de Biología Molecular Vegetal, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653 Ñuñoa, Santiago, Chile Current address: Max Planck Institut für Molekulare Pflanzenphysiologie, Potsdam-Golm, Germany.
authors.forename: J C
authors.initials: JC
authors.lastname: Moreno
authors.affiliation: Centro de Biología Molecular Vegetal, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653 Ñuñoa, Santiago, Chile.
authors.forename: A
authors.initials: A
authors.lastname: Cerda
authors.affiliation: Centro de Biología Molecular Vegetal, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653 Ñuñoa, Santiago, Chile.
authors.forename: K
authors.initials: K
authors.lastname: Simpson
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, C.S.I.C., Universidad Politécnica de Valencia, Ingeniero Fausto Elío s/n, 46022 Valencia, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Lopez-Diaz
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, C.S.I.C., Universidad Politécnica de Valencia, Ingeniero Fausto Elío s/n, 46022 Valencia, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Carrera
authors.affiliation: Centro de Biología Molecular Vegetal, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653 Ñuñoa, Santiago, Chile.
authors.forename: M
authors.initials: M
authors.lastname: Handford
authors.affiliation: Centro de Biología Molecular Vegetal, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, Casilla 653 Ñuñoa, Santiago, Chile cstange@uchile.cl.
authors.forename: C
authors.initials: C
authors.lastname: Stange
mesh_terms: D018533:Biomass; D053898:Biosynthetic Pathways / Q000235:genetics; D002338:Carotenoids / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism*; D018552:Daucus carota / Q000201:enzymology*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005875:Gibberellins / Q000378:metabolism*; D019753:Intramolecular Lyases / Q000378:metabolism*; D008954:Models, Biological; D010641:Phenotype; D010788:Photosynthesis; D030821:Plants, Genetically Modified; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*
chemical_list: D005875:Gibberellins; D002734:Chlorophyll; D002338:Carotenoids; D019753:Intramolecular Lyases; C070925:lycopene cyclase-isomerase
keywords: Biomass; carotenoids; chlorophyll; gene expression; gibberellins; lycopene β-cyclase; tobacco.