Abstract: Methods of increasing production, stability or activity of a target polypeptide are provided herein. The method includes increasing the level of an antioxidant in a cell comprising a polynucleotide encoding the target polypeptide. Also provided are cells and transgenic organisms produced using the methods described herein. Methods of treating a subject with a condition treatable by administration of the target polypeptide are also disclosed. Finally methods and compositions for transiently increasing antioxidants in plant cells are provided.

Abstract: Ascorbate protects tissues against damage caused by reactive oxygen species (ROS) produced through normal metabolism or generated from stress. The inositol route to AsA involves four enzymes: myo-inositol oxygenase, glucuronate reductase, gluconolactonase (GNL), and L-gulono-1,4-lactone oxidase (GulLO). Eighteen putative GNLs were identified in Arabidopsis, one of which, AtGNL, is interesting because it possesses a chloroplastic signal peptide. Knockouts on this gene had lower foliar AsA and stunted growth compared to controls. The functional gene restored the phenotype of the knockouts, and those plants had higher AsA content, enhanced photosynthetic capacity, and higher seed yield.

Abstract: Ascorbate protects tissues against damage caused by reactive oxygen species (ROS) produced through normal metabolism or generated from stress. The inositol route to AsA involves four enzymes: myo-inositol oxygenase, glucuronate reductase, gluconolactonase (GNL), and L-gulono-1,4-lactone oxidase (GulLO). Eighteen putative GNLs were identified in Arabidopsis, one of which, AtGNL, is interesting because it possesses a chloroplastic signal peptide. Knockouts on this gene had lower foliar AsA and stunted growth compared to controls. The functional gene restored the phenotype of the knockouts, and those plants had higher AsA content, enhanced photosynthetic capacity, and higher seed yield.

Abstract: Ascorbate protects tissues against damage caused by reactive oxygen species (ROS) produced through normal metabolism or generated from stress. The inositol route to AsA involves four enzymes: myo-inositol oxygenase, glucuronate reductase, gluconolactonase (GNL), and L-gulono-1,4-lactone oxidase (GulLO). Eighteen putative GNLs were identified in Arabidopsis, one of which, AtGNL, is interesting because it possesses a chloroplastic signal peptide. Knockouts on this gene had lower foliar AsA and stunted growth compared to controls. The functional gene restored the phenotype of the knockouts, and those plants had higher AsA content, enhanced photosynthetic capacity, and higher seed yield.

Abstract: Methods are provided for increasing plant growth rate, biomass and tolerance to stress by genetically engineering plants to contain and express a gene of the ascorbic acid synthesis-cell wall synthesis network (e.g. GlcUA reductase, GLOase or MIOX). Transgenic plants that are genetically engineered in such a manner are also provided.

Abstract: Methods of increasing production, stability or activity of a target polypeptide are provided herein. The method includes increasing the level of an antioxidant in a cell comprising a polynucleotide encoding the target polypeptide. Also provided are cells and transgenic organisms produced using the methods described herein. Methods of treating a subject with a condition treatable by administration of the target polypeptide are also disclosed. Finally methods and compositions for transiently increasing antioxidants in plant cells are provided.

Abstract: Methods are provided for increasing plant growth rate, biomass and tolerance to stress by genetically engineering plants to contain and express a gene of the ascorbic acid synthesis-cell wall synthesis network (e.g. GlcUA reductase, GLOase or MIOX). Transgenic plants that are genetically engineered in such a manner are also provided.

Abstract: Methods for increasing the vitamin C content of plants are provided by transforming the plants with genes encoding a novel vitamin C biosynthetic pathway. Vitamin C production is increased in the resulting transgenic plants, providing, for example, higher nutritional value and longer shelf-life of produce. Further, the leaves of air-cured varieties of tobacco transformed in this manner contain lower levels of highly carcinogenic tobacco specific nitrosamines (TSNAs).