Increased Vitamin C Content Accompanied by an Enhanced Recycling Pathway Confers Oxidative Stress Tolerance in Arabidopsis

Authors

  • Zinan Wang,

    1. State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan-SJTU-Nottingham Plant Biotechnology R&D Center, Fudan University, Shanghai 200433, China
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  • Ying Xiao,

    1. Department of Pharmacognosy, School of Pharmacy, Second Military Medical University, Shanghai 200433, China
    2. Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China
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  • Wansheng Chen,

    1. Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China
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  • Kexuan Tang,

    Corresponding author
    1. State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan-SJTU-Nottingham Plant Biotechnology R&D Center, Fudan University, Shanghai 200433, China
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  • Lei Zhang

    Corresponding author
    1. Department of Pharmacognosy, School of Pharmacy, Second Military Medical University, Shanghai 200433, China
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*Corresponding author
Tel: +86 21 6564 2772; Fax: +86 21 6564 3552; E-mail: kxtang@fudan.edu.cn
Tel: +86 21 8187 1309; Fax: +86 21 8187 1305; E-mail: zhanglei@smmu.edu.cn

Abstract

Vitamin C (L-ascorbic acid, AsA) has important antioxidant and metabolic functions in both plants and animals. Once used, ascorbic acid can be regenerated from its oxidized form in a reaction catalyzed by dehydroascorbate reductase (DHAR, EC 1.8.5.1). To analyze the physiological role of DHAR catalyzing the reduction of DHA to ascorbate in environmental stress adaptation, we examined whether increasing the level of AsA through enhanced AsA recycling would limit the deleterious effects of oxidative stress. A chimeric construct consisting of the double CaMV35S promoter fused to the Myc-dhar gene was introduced into Arabidopsis thaliana. Transgenic plants were biochemically characterized and tested for responses to oxidative stress. Western blot indicated that the dhar-transgene was successfully expressed. In homozygous T4 transgenic seedlings, DHAR overexpression was increased up to 1.5 to 5.4 fold, which enhanced foliar ascorbic acid levels 2- to 4.25-fold and ratio of AsA/DHA about 3- to 16-fold relative to wild type. In addition, the level of glutathione, the reductant used by DHAR, also increased as did its redox state. When whole plants were treated with high light and high temperature stress or in vitro leaf discs were subjected to 10 μM paraquat, transgenic plants showed a larger AsA pool size, lower membrane damage, and a higher level of chlorophyll compared with controls. These data suggested that increasing the plant vitamin C content through enhanced ascorbate recycling could limit the deleterious effects of environmental oxidative stress.

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