title: Mild reductions in cytosolic NADP-dependent isocitrate dehydrogenase activity result in lower amino acid contents and pigmentation without impacting growth.
abstract: Transgenic tomato (Solanum lycopersicum) plants were generated targeting the cytosolic NADP-dependent isocitrate dehydrogenase gene (SlICDH1) via the RNA interference approach. The resultant transformants displayed a relatively mild reduction in the expression and activity of the target enzyme in the leaves. However, biochemical analyses revealed that the transgenic lines displayed a considerable shift in metabolism, being characterized by decreases in the levels of the TCA cycle intermediates, total amino acids, photosynthetic pigments, starch and NAD(P)H. The plants showed little change in photosynthesis with the exception of a minor decrease in maximum photosynthetic efficiency (F (v)/F (m)), and a small decrease in growth compared to the wild type. These results reveal that even small changes in cytosolic NADP-dependent isocitrate dehydrogenase activity lead to noticeable alterations in the activities of enzymes involved in primary nitrate assimilation and in the synthesis of 2-oxoglutarate derived amino acids. These data are discussed within the context of current models for the role of the various isoforms of isocitrate dehydrogenase within plant amino acid metabolism.
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, Potsdam-Golm, Germany.
authors.forename: Ronan
authors.initials: R
authors.lastname: Sulpice
authors.forename: Agata
authors.initials: A
authors.lastname: Sienkiewicz-Porzucek
authors.forename: Sonia
authors.initials: S
authors.lastname: Osorio
authors.forename: Ina
authors.initials: I
authors.lastname: Krahnert
authors.forename: Mark
authors.initials: M
authors.lastname: Stitt
authors.forename: Alisdair R
authors.initials: AR
authors.lastname: Fernie
authors.forename: Adriano
authors.initials: A
authors.lastname: Nunes-Nesi
mesh_terms: D000596:Amino Acids / Q000032:analysis*; D019069:Cell Respiration; D002952:Citric Acid Cycle / Q000502:physiology; D003600:Cytosol / Q000201:enzymology / Q000378:metabolism; D018076:DNA, Complementary; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007521:Isocitrate Dehydrogenase / Q000378:metabolism*; D007656:Ketoglutaric Acids / Q000378:metabolism; D018551:Solanum lycopersicum / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010788:Photosynthesis / Q000235:genetics; D010858:Pigmentation; D010860:Pigments, Biological / Q000378:metabolism; D018515:Plant Leaves / Q000201:enzymology / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D016133:Polymerase Chain Reaction; D018749:RNA, Plant / Q000235:genetics
chemical_list: D000596:Amino Acids; D018076:DNA, Complementary; D007656:Ketoglutaric Acids; D010860:Pigments, Biological; D018749:RNA, Plant; D009249:NADP; D007521:Isocitrate Dehydrogenase; D009584:Nitrogen
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