title: Suppressing Farnesyl Diphosphate Synthase Alters Chloroplast Development and Triggers Sterol-Dependent Induction of Jasmonate- and Fe-Related Responses.
abstract: Farnesyl diphosphate synthase (FPS) catalyzes the synthesis of farnesyl diphosphate from isopentenyl diphosphate and dimethylallyl diphosphate. Arabidopsis (Arabidopsis thaliana) contains two genes (FPS1 and FPS2) encoding FPS. Single fps1 and fps2 knockout mutants are phenotypically indistinguishable from wild-type plants, while fps1/fps2 double mutants are embryo lethal. To assess the effect of FPS down-regulation at postembryonic developmental stages, we generated Arabidopsis conditional knockdown mutants expressing artificial microRNAs devised to simultaneously silence both FPS genes. Induction of silencing from germination rapidly caused chlorosis and a strong developmental phenotype that led to seedling lethality. However, silencing of FPS after seed germination resulted in a slight developmental delay only, although leaves and cotyledons continued to show chlorosis and altered chloroplasts. Metabolomic analyses also revealed drastic changes in the profile of sterols, ubiquinones, and plastidial isoprenoids. RNA sequencing and reverse transcription-quantitative polymerase chain reaction transcriptomic analysis showed that a reduction in FPS activity levels triggers the misregulation of genes involved in biotic and abiotic stress responses, the most prominent one being the rapid induction of a set of genes related to the jasmonic acid pathway. Down-regulation of FPS also triggered an iron-deficiency transcriptional response that is consistent with the iron-deficient phenotype observed in FPS-silenced plants. The specific inhibition of the sterol biosynthesis pathway by chemical and genetic blockage mimicked these transcriptional responses, indicating that sterol depletion is the primary cause of the observed alterations. Our results highlight the importance of sterol homeostasis for normal chloroplast development and function and reveal important clues about how isoprenoid and sterol metabolism is integrated within plant physiology and development.
authors.affiliation: Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics, CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra (Cerdanyola del Vallès), Barcelona, Spain (D.M., P.A., D.C., T.A., M.A., A.F.); andDepartment of Biochemistry and Molecular Biology (D.M., P.A., D.C., M.A., A.F.) and Plant Physiology Unit (T.A.), Faculty of Pharmacy, University of Barcelona, Barcelona, Spain david.manzano@ub.edu.
authors.forename: David
authors.identifier: 0000-0002-5483-7223
authors.initials: D
authors.lastname: Manzano
authors.affiliation: Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics, CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra (Cerdanyola del Vallès), Barcelona, Spain (D.M., P.A., D.C., T.A., M.A., A.F.); andDepartment of Biochemistry and Molecular Biology (D.M., P.A., D.C., M.A., A.F.) and Plant Physiology Unit (T.A.), Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Paola
authors.initials: P
authors.lastname: Andrade
authors.affiliation: Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics, CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra (Cerdanyola del Vallès), Barcelona, Spain (D.M., P.A., D.C., T.A., M.A., A.F.); andDepartment of Biochemistry and Molecular Biology (D.M., P.A., D.C., M.A., A.F.) and Plant Physiology Unit (T.A.), Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Caudepón
authors.affiliation: Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics, CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra (Cerdanyola del Vallès), Barcelona, Spain (D.M., P.A., D.C., T.A., M.A., A.F.); andDepartment of Biochemistry and Molecular Biology (D.M., P.A., D.C., M.A., A.F.) and Plant Physiology Unit (T.A.), Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Teresa
authors.identifier: 0000-0002-6915-5823
authors.initials: T
authors.lastname: Altabella
authors.affiliation: Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics, CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra (Cerdanyola del Vallès), Barcelona, Spain (D.M., P.A., D.C., T.A., M.A., A.F.); andDepartment of Biochemistry and Molecular Biology (D.M., P.A., D.C., M.A., A.F.) and Plant Physiology Unit (T.A.), Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Arró
authors.affiliation: Plant Metabolism and Metabolic Engineering Program, Centre for Research in Agricultural Genomics, CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra (Cerdanyola del Vallès), Barcelona, Spain (D.M., P.A., D.C., T.A., M.A., A.F.); andDepartment of Biochemistry and Molecular Biology (D.M., P.A., D.C., M.A., A.F.) and Plant Physiology Unit (T.A.), Faculty of Pharmacy, University of Barcelona, Barcelona, Spain.
authors.forename: Albert
authors.identifier: 0000-0002-0741-2388
authors.initials: A
authors.lastname: Ferrer
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D015153:Blotting, Western; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism* / Q000494:pharmacology; D020869:Gene Expression Profiling / Q000379:methods; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D063990:Gene Ontology; D020868:Gene Silencing; D051228:Geranyltranstransferase / Q000235:genetics / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D054883:Oxylipins / Q000378:metabolism* / Q000494:pharmacology; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013261:Sterols / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D054883:Oxylipins; D013261:Sterols; C011006:jasmonic acid; D007501:Iron; D051228:Geranyltranstransferase