title: Redox regulation of ascorbate and glutathione by a chloroplastic dehydroascorbate reductase is required for high-light stress tolerance in Arabidopsis.
abstract: Chloroplasts are a significant site for reactive oxygen species production under illumination and, thus, possess a well-organized antioxidant system involving ascorbate. Ascorbate recycling occurs in different manners in this system, including a dehydroascorbate reductase (DHAR) reaction. We herein investigated the physiological significance of DHAR3 in photo-oxidative stress tolerance in Arabidopsis. GFP-fused DHAR3 protein was targeted to chloroplasts in Arabidopsis leaves. A DHAR3 knockout mutant exhibited sensitivity to high light (HL). Under HL, the ascorbate redox states were similar in mutant and wild-type plants, while total ascorbate content was significantly lower in the mutant, suggesting that DHAR3 contributes, at least to some extent, to ascorbate recycling. Activation of monodehydroascorbate reductase occurred in dhar3 mutant, which might compensate for the lack of DHAR3. Interestingly, glutathione oxidation was consistently inhibited in dhar3 mutant. These findings indicate that DHAR3 regulates both ascorbate and glutathione redox states to acclimate to HL.
authors.affiliation: a Faculty of Agriculture, Department of Advanced Bioscience , Kinki University , Nara , Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Noshi
authors.affiliation: a Faculty of Agriculture, Department of Advanced Bioscience , Kinki University , Nara , Japan.
authors.forename: Risa
authors.initials: R
authors.lastname: Hatanaka
authors.affiliation: a Faculty of Agriculture, Department of Advanced Bioscience , Kinki University , Nara , Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Tanabe
authors.affiliation: b Faculty of Life and Environmental Science, Department of Life Science and Biotechnology , Shimane University , Matsue , Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Terai
authors.affiliation: b Faculty of Life and Environmental Science, Department of Life Science and Biotechnology , Shimane University , Matsue , Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Maruta
authors.affiliation: a Faculty of Agriculture, Department of Advanced Bioscience , Kinki University , Nara , Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Shigeoka
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000975:Antioxidants / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism / Q000528:radiation effects*; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D005978:Glutathione / Q000378:metabolism; D008027:Light; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000172:deficiency / Q000235:genetics*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D030821:Plants, Genetically Modified; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000975:Antioxidants; D029681:Arabidopsis Proteins; D017382:Reactive Oxygen Species; D010088:Oxidoreductases; C020666:glutathione dehydrogenase (ascorbate); D005978:Glutathione; D001205:Ascorbic Acid
keywords: Arabidopsis thaliana; ascorbate; dehydroascorbate reductase; photo-oxidative stress; redox regulation