title: Knocking down mitochondrial iron transporter (MIT) reprograms primary and secondary metabolism in rice plants.
abstract: Iron (Fe) is an essential micronutrient for plant growth and development, and its reduced bioavailability strongly impairs mitochondrial functionality. In this work, the metabolic adjustment in the rice (Oryza sativa) mitochondrial Fe transporter knockdown mutant (mit-2) was analysed. Biochemical characterization of purified mitochondria from rice roots showed alteration in the respiratory chain of mit-2 compared with wild-type (WT) plants. In particular, proteins belonging to the type II alternative NAD(P)H dehydrogenases accumulated strongly in mit-2 plants, indicating that alternative pathways were activated to keep the respiratory chain working. Additionally, large-scale changes in the transcriptome and metabolome were observed in mit-2 rice plants. In particular, a strong alteration (up-/down-regulation) in the expression of genes encoding enzymes of both primary and secondary metabolism was found in mutant plants. This was reflected by changes in the metabolic profiles in both roots and shoots of mit-2 plants. Significant alterations in the levels of amino acids belonging to the aspartic acid-related pathways (aspartic acid, lysine, and threonine in roots, and aspartic acid and ornithine in shoots) were found that are strictly connected to the Krebs cycle. Furthermore, some metabolites (e.g. pyruvic acid, fumaric acid, ornithine, and oligosaccharides of the raffinose family) accumulated only in the shoot of mit-2 plants, indicating possible hypoxic responses. These findings suggest that the induction of local Fe deficiency in the mitochondrial compartment of mit-2 plants differentially affects the transcript as well as the metabolic profiles in root and shoot tissues.
authors.affiliation: Dipartimento di Scienze Agrarie e Ambientali-Produzione, Territorio, Agroenergia, Università degli Studi di Milano, via Celoria 2-20133 Milano, Italy gianpiero.vigani@unimi.it khurram.bashir@riken.jp.
authors.forename: Gianpiero
authors.initials: G
authors.lastname: Vigani
authors.affiliation: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, , Yokohama, Kanagawa 230-0045, Japan gianpiero.vigani@unimi.it khurram.bashir@riken.jp.
authors.forename: Khurram
authors.initials: K
authors.lastname: Bashir
authors.affiliation: Graduate School of Science, Tohoku University, 6-3, Aramaki-aza Aoba, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ishimaru
authors.affiliation: Plant Molecular Biology (Botany) and Plant Metabolism, Department Biology I, Ludwig-Maximilians-Universität München (LMU), Großhaderner Straße 2, D-82152 Planegg-Martinsried, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Lehmann
authors.affiliation: Dipartimento di Scienze Agrarie e Ambientali-Produzione, Territorio, Agroenergia, Università degli Studi di Milano, via Celoria 2-20133 Milano, Italy.
authors.forename: Fabio Marco
authors.initials: FM
authors.lastname: Casiraghi
authors.affiliation: Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nakanishi
authors.affiliation: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, , Yokohama, Kanagawa 230-0045, Japan CREST, JST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Motoaki
authors.initials: M
authors.lastname: Seki
authors.affiliation: Plant Molecular Biology (Botany) and Plant Metabolism, Department Biology I, Ludwig-Maximilians-Universität München (LMU), Großhaderner Straße 2, D-82152 Planegg-Martinsried, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Geigenberger
authors.affiliation: Dipartimento di Scienze Agrarie e Ambientali-Produzione, Territorio, Agroenergia, Università degli Studi di Milano, via Celoria 2-20133 Milano, Italy.
authors.forename: Graziano
authors.initials: G
authors.lastname: Zocchi
authors.affiliation: Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi-shi, Ishikawa 921-8836, Japan.
authors.forename: Naoko K
authors.initials: NK
authors.lastname: Nishizawa
mesh_terms: D004579:Electron Transport; D018506:Gene Expression Regulation, Plant; D055785:Gene Knockdown Techniques; D017343:Genes, Plant; D007501:Iron / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D055442:Metabolome / Q000235:genetics; D055432:Metabolomics; D008928:Mitochondria / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D025341:Principal Component Analysis; D064210:Secondary Metabolism / Q000235:genetics; D014158:Transcription, Genetic; D059467:Transcriptome / Q000235:genetics
chemical_list: D026901:Membrane Transport Proteins; D010940:Plant Proteins; D007501:Iron
keywords: Iron; Oryza sativa; iron deficiency; metabolomics; mitochondria; transcriptomics