title: Combined transcript, proteome, and metabolite analysis of transgenic maize seeds engineered for enhanced carotenoid synthesis reveals pleotropic effects in core metabolism.
abstract: The aim of this study was to assess whether endosperm-specific carotenoid biosynthesis influenced core metabolic processes in maize embryo and endosperm and how global seed metabolism adapted to this expanded biosynthetic capacity. Although enhancement of carotenoid biosynthesis was targeted to the endosperm of maize kernels, a concurrent up-regulation of sterol and fatty acid biosynthesis in the embryo was measured. Targeted terpenoid analysis, and non-targeted metabolomic, proteomic, and transcriptomic profiling revealed changes especially in carbohydrate metabolism in the transgenic line. In-depth analysis of the data, including changes of metabolite pools and increased enzyme and transcript concentrations, gave a first insight into the metabolic variation precipitated by the higher up-stream metabolite demand by the extended biosynthesis capacities for terpenoids and fatty acids. An integrative model is put forward to explain the metabolic regulation for the increased provision of terpenoid and fatty acid precursors, particularly glyceraldehyde 3-phosphate and pyruvate or acetyl-CoA from imported fructose and glucose. The model was supported by higher activities of fructokinase, glucose 6-phosphate isomerase, and fructose 1,6-bisphosphate aldolase indicating a higher flux through the glycolytic pathway. Although pyruvate and acetyl-CoA utilization was higher in the engineered line, pyruvate kinase activity was lower. A sufficient provision of both metabolites may be supported by a by-pass in a reaction sequence involving phosphoenolpyruvate carboxylase, malate dehydrogenase, and malic enzyme.
authors: Unité de Biochimie et Physiologie Moléculaire des Plantes, INRA, 34060 Montpellier, France.
authors: Mathilde
authors: M
authors: Decourcelle
authors: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 OEX, UK.
authors: Laura
authors: L
authors: Perez-Fons
authors: PartnerChip, Genopole Campus 2, 91000 Evry, France.
authors: Sylvain
authors: S
authors: Baulande
authors: Biosynthesis Group, Institute of Molecular Biosciences, Goethe University Frankfurt/M, Max von Laue Str. 9, D-60438 Frankfurt, Germany.
authors: Sabine
authors: S
authors: Steiger
authors: PartnerChip, Genopole Campus 2, 91000 Evry, France.
authors: Linhdavanh
authors: L
authors: Couvelard
authors: Unité de Biochimie et Physiologie Moléculaire des Plantes, INRA, 34060 Montpellier, France.
authors: Sonia
authors: S
authors: Hem
authors: Department of Plant Production and Forestry Science, University of Lleida-Agrotecnio Center, 25198 Lleida, Spain.
authors: Changfu
authors: C
authors: Zhu
authors: Department of Plant Production and Forestry Science, University of Lleida-Agrotecnio Center, 25198 Lleida, Spain.
authors: Teresa
authors: T
authors: Capell
authors: Department of Plant Production and Forestry Science, University of Lleida-Agrotecnio Center, 25198 Lleida, Spain Institució Catalana de Recerca i Estudis Avancats, 08010 Barcelona, Spain.
authors: Paul
authors: P
authors: Christou
authors: School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 OEX, UK.
authors: Paul
authors: P
authors: Fraser
authors: Biosynthesis Group, Institute of Molecular Biosciences, Goethe University Frankfurt/M, Max von Laue Str. 9, D-60438 Frankfurt, Germany sandmann@bio.uni-frankfurt.de.
authors: Gerhard
authors: G
authors: Sandmann
mesh_terms: D053898:Biosynthetic Pathways / Q000235:genetics; D050260:Carbohydrate Metabolism / Q000235:genetics; D002338:Carotenoids / Q000096:biosynthesis / Q000235:genetics; D056625:Endosperm / Q000235:genetics / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D055442:Metabolome; D008954:Models, Biological; D030821:Plants, Genetically Modified; D020543:Proteome; D012333:RNA, Messenger / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D012639:Seeds / Q000235:genetics / Q000378:metabolism*; D059467:Transcriptome; D015854:Up-Regulation; D003313:Zea mays / Q000235:genetics / Q000378:metabolism*
chemical_list: D005227:Fatty Acids; D020543:Proteome; D012333:RNA, Messenger; D018749:RNA, Plant; D002338:Carotenoids
keywords: GM maize; Genetically engineered carotenoid biosynthesis; metabolomics; pathway regulation; proteomics; transcriptomics.