title: Overexpression of Arabidopsis thaliana farnesyl diphosphate synthase (FPS1S) in transgenic Arabidopsis induces a cell death/senescence-like response and reduced cytokinin levels.
abstract: To investigate the contribution of farnesyl diphosphate synthase (FPS) to the overall control of the mevalonic acid pathway in plants, we have generated transgenic Arabidopsis thaliana overexpressing the Arabidopsis FPS1S isoform. Despite high levels of FPS activity in transgenic plants (8- to 12-fold as compared to wild-type plants), the content of sterols and the levels of 3-hydroxy-3-methylglutaryl-CoA reductase activity in leaves were similar to those in control plants. Plants overexpressing FPS1S showed a cell death/senescence-like phenotype and grew less vigorously than wild-type plants. The onset and the severity of these phenotypes directly correlated with the levels of FPS activity. In leaves of plants with increased FPS activity, the expression of the senescence activated gene SAG12 was prematurely induced. Transgenic plants grown in the presence of either mevalonic acid (MVA) or the cytokinin 2-isopentenyladenine (2-iP) recovered the wild-type phenotype. Quantification of endogenous cytokinins demonstrated that FPS1S overexpression specifically reduces the levels of endogenous zeatin-type cytokinins in leaves. Altogether these results support the notion that increasing FPS activity without a concomitant increase of MVA production leads to a reduction of IPP and DMAPP available for cytokinin biosynthesis. The reduced cytokinin levels would be, at least in part, responsible for the phenotypic alterations observed in the transgenic plants. The finding that wild-type and transgenic plants accumulated similar increased amounts of sterols when grown in the presence of exogenous MVA suggests that FPS1S is not limiting for sterol biosynthesis.
authors: Departament de Bioquímica i Biologia Molecular, Facultat de Farmàcia, Universitat de Barcelona, Avinguda, Diagonal 643, 08028-Barcelona, Spain.
authors: Angela
authors: A
authors: Masferrer
authors: Montserrat
authors: M
authors: Arró
authors: David
authors: D
authors: Manzano
authors: Hubert
authors: H
authors: Schaller
authors: Xavier
authors: X
authors: Fernández-Busquets
authors: Paloma
authors: P
authors: Moncaleán
authors: Belén
authors: B
authors: Fernández
authors: Núria
authors: N
authors: Cunillera
authors: Albert
authors: A
authors: Boronat
authors: Albert
authors: A
authors: Ferrer
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000166:cytology* / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism; D015153:Blotting, Western; D016923:Cell Death; D003546:Cysteine Endopeptidases / Q000378:metabolism; D003583:Cytokinins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D051228:Geranyltranstransferase; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008798:Mevalonic Acid / Q000378:metabolism; D010641:Phenotype; D010940:Plant Proteins; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000032:analysis; D018749:RNA, Plant / Q000032:analysis; D013261:Sterols / Q000032:analysis
chemical_list: D029681:Arabidopsis Proteins; D003583:Cytokinins; D007527:Isoenzymes; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D013261:Sterols; D019883:Alkyl and Aryl Transferases; D051228:Geranyltranstransferase; C402082:SAG12 protein, Arabidopsis; D003546:Cysteine Endopeptidases; D008798:Mevalonic Acid