title: Ascorbate biosynthesis and its involvement in stress tolerance and plant development in rice (Oryza sativa L.).
abstract: Ascorbic acid (AsA) biosynthesis and its implications for stress tolerance and plant development were investigated in a set of rice knock-out (KO) mutants for AsA biosynthetic genes and their wild-types. KO of two isoforms of GDP-D-mannose epimerase (OsGME) reduced the foliar AsA level by 20-30%, and KO of GDP-L-galactose phosphorylase (OsGGP) by 80%, while KO of myo-inositol oxygenase (OsMIOX) did not affect foliar AsA levels. AsA concentration was negatively correlated with lipid peroxidation in foliar tissue under ozone stress and zinc deficiency, but did not affect the sensitivity to iron toxicity. Lack of AsA reduced the photosynthetic efficiency as represented by the maximum carboxylation rate of Rubisco (Vmax), the maximum electron transport rate (Jmax) and the chlorophyll fluorescence parameter ΦPSII. Mutants showed lower biomass production than their wild-types, especially when OsGGP was lacking (around 80% reductions). All plants except for KO mutants of OsGGP showed distinct peaks in foliar AsA concentrations during the growth, which were consistent with up-regulation of OsGGP, suggesting that OsGGP plays a pivotal role in regulating foliar AsA levels during different growth stages. In conclusion, our data demonstrate multiple roles of AsA in stress tolerance and development of rice.
authors.affiliation: Institute of Crop Science and Resource Conservation (INRES), Abiotic Stress Tolerance in Crops, University of Bonn, Karlrobert-Kreiten Strasse 13, 53115, Bonn, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Höller
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Ueda
authors.forename: Linbo
authors.initials: L
authors.lastname: Wu
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Wang
authors.forename: Mohammad-Reza
authors.initials: MR
authors.lastname: Hajirezaei
authors.forename: Mohammad-Reza
authors.initials: MR
authors.lastname: Ghaffari
authors.forename: Nicolaus
authors.initials: N
authors.lastname: von Wirén
authors.forename: Michael
authors.initials: M
authors.lastname: Frei
mesh_terms: D001205:Ascorbic Acid / Q000096:biosynthesis*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D050562:Inositol Oxygenase / Q000235:genetics / Q000378:metabolism; D007501:Iron; D012275:Oryza / Q000254:growth & development* / Q000378:metabolism*; D010126:Ozone; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism; D063245:Plant Development / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological / Q000502:physiology*; D015032:Zinc
chemical_list: D010940:Plant Proteins; D010126:Ozone; D007501:Iron; D050562:Inositol Oxygenase; D010744:Phosphoric Monoester Hydrolases; D015032:Zinc; D001205:Ascorbic Acid