l-Ascorbic acid (vitamin C) is an abundant metabolite in plant cells and tissues. Ascorbate functions as an antioxidant, as an enzyme cofactor, and plays essential roles in multiple physiological processes including photosynthesis, photoprotection, control of cell cycle and cell elongation, and modulation of flowering time, gene regulation, and senescence. The importance of this key molecule in regulating whole plant morphology, cell structure, and plant development has been clearly established via characterization of low vitamin C mutants of Arabidopsis, potato, tobacco, tomato, and rice. However, the consequences of elevating ascorbate content in plant growth and development are poorly understood. Here we demonstrate that Arabidopsis lines over-expressing a myo-inositol oxygenase or an l-gulono-1,4-lactone oxidase, containing elevated ascorbate, display enhanced growth and biomass accumulation of both aerial and root tissues. To our knowledge this is the first study demonstrating such a marked positive effect in plant growth in lines engineered to contain elevated vitamin C content. In addition, we present evidence showing that these lines are tolerant to a wide range of abiotic stresses including salt, cold, and heat. Total ascorbate content of the transgenic lines remained higher than those of controls under the abiotic stresses tested. Interestingly, exposure to pyrene, a polycyclic aromatic hydrocarbon and known inducer of oxidative stress in plants, leads to stunted growth of the aerial tissue, reduction in the number of root hairs, and inhibition of leaf expansion in wild type plants, while these symptoms are less severe in the over-expressers. Our results indicate the potential of this metabolic engineering strategy to develop crops with enhanced biomass, abiotic stress tolerance, and phytoremediation capabilities.

中文翻译：

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通过在拟南芥中过量表达肌醇加氧酶和1-gulono-1,4-内酯氧化酶来提高维生素C含量，可提高生物量和对非生物胁迫的耐受性。

l抗坏血酸（维生素C）是植物细胞和组织中的一种丰富的代谢产物。抗坏血酸作为抗氧化剂，酶的辅助因子，在多种生理过程中起着至关重要的作用，包括光合作用，光保护，控制细胞周期和细胞伸长，调节开花时间，基因调控和衰老。通过表征拟南芥，马铃薯，烟草，番茄和水稻的低维生素C突变体，已经清楚地确定了该关键分子在调节整个植物形态，细胞结构和植物发育中的重要性。但是，人们对植物体内生长和发育中抗坏血酸含量升高的后果知之甚少。在这里，我们证明了拟南芥系过表达含有较高抗坏血酸的肌醇加氧酶或1-gulono-1,4-内酯氧化酶，显示出气生和根组织的生长和生物量积累增强。据我们所知，这是第一项研究，证明在设计中含有较高维生素C含量的品系对植物生长具有显着的积极作用。此外，我们提供的证据表明，这些品系能够耐受各种非生物胁迫，包括盐，冷和热。在测试的非生物胁迫下，转基因品系的总抗坏血酸含量仍高于对照。有趣的是，暴露于pyr，多环芳烃和植物中已知的氧化应激诱导剂，会导致气生组织发育迟缓，根毛减少，野生型植物叶片膨胀受到抑制，而这些症状是在过度表达中不那么严重。