title: Arabidopsis dehydroascorbate reductase 1 and 2 modulate redox states of ascorbate-glutathione cycle in the cytosol in response to photooxidative stress.
abstract: Ascorbate and glutathione are indispensable cellular redox buffers and allow plants to acclimate stressful conditions. Arabidopsis contains three functional dehydroascorbate reductases (DHAR1-3), which catalyzes the conversion of dehydroascorbate into its reduced form using glutathione as a reductant. We herein attempted to elucidate the physiological role in DHAR1 and DHAR2 in stress responses. The total DHAR activities in DHAR knockout Arabidopsis plants, dhar1 and dhar2, were 22 and 92%, respectively, that in wild-type leaves. Under high light (HL), the levels of total ascorbate and dehydroascorbate were only reduced and increased, respectively, in dhar1. The oxidation of glutathione under HL was significantly inhibited in both dhar1 and dhar2, while glutathione contents were only enhanced in dhar1. The dhar1 showed stronger visible symptoms than the dhar2 under photooxidative stress conditions. Our results demonstrated a pivotal role of DHAR1 in the modulation of cellular redox states under photooxidative stress.
authors.affiliation: a Faculty of Agriculture, Department of Advanced Bioscience , Kindai University , Nara , Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Noshi
authors.affiliation: a Faculty of Agriculture, Department of Advanced Bioscience , Kindai University , Nara , Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yamada
authors.affiliation: a Faculty of Agriculture, Department of Advanced Bioscience , Kindai University , Nara , Japan.
authors.forename: Risa
authors.initials: R
authors.lastname: Hatanaka
authors.affiliation: a Faculty of Agriculture, Department of Advanced Bioscience , Kindai University , Nara , Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Tanabe
authors.affiliation: a Faculty of Agriculture, Department of Advanced Bioscience , Kindai University , Nara , Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tamoi
authors.affiliation: a Faculty of Agriculture, Department of Advanced Bioscience , Kindai University , Nara , Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Shigeoka
mesh_terms: D017360:Arabidopsis / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001205:Ascorbic Acid / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005978:Glutathione / Q000378:metabolism*; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C000614665:DHAR2 protein, Arabidopsis; D010088:Oxidoreductases; C519170:DHAR1 protein, Arabidopsis; D005982:Glutathione Transferase; D005978:Glutathione; D001205:Ascorbic Acid
keywords: DHAR; ascorbate; glutathione; oxidative stress; redox regulation