title: Ascorbic acid contents in transgenic potato plants overexpressing two dehydroascorbate reductase genes.
abstract: Ascorbic acid (AsA, vitamin C) is one of the most important nutritional quality factors in many horticultural crops and has many biological activities in the human body. Dehydroascorbate reductase (EC 1.8.5.1; DHAR) plays an important role in maintaining the normal level of ascorbic acid (AsA) by recycling oxidized ascorbic acid. To increase AsA content of potato, we isolated and characterized the cDNAs encoding two isoform DHARs localized in cytosol and chloroplast from potato, and developed two types of transgenic potato plants overexpressing cytosolic DHAR gene and chloroplastic DHAR, respectively. Incorporation of the transgene in the genome of potato was confirmed by PCR and real time RT-PCR. The overexpression of cytosolic DHAR significantly increased DHAR activities and AsA contents in potato leaves and tubers, whereas chloroplastic DHAR overexpression only increased DHAR activities and AsA contents in leaves, and did not change them in tubers. These results indicated that AsA content of potato can be elevated by enhancing recycling ascorbate via DHAR overexpression, moreover, cytosolic DHAR might play main important roles in improving the AsA contents of potato tubers.
authors.affiliation: Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Aiguo
authors.initials: A
authors.lastname: Qin
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Shi
authors.forename: Xianchang
authors.initials: X
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D001205:Ascorbic Acid / Q000378:metabolism*; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D003683:Dehydroascorbic Acid / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D030821:Plants, Genetically Modified; D011198:Solanum tuberosum / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D014170:Transformation, Genetic
chemical_list: D018076:DNA, Complementary; D010088:Oxidoreductases; C020666:glutathione dehydrogenase (ascorbate); D001205:Ascorbic Acid; D003683:Dehydroascorbic Acid