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Metabolic engineering of vitamin C production in Arabidopsis

Xiao, Ling, Xiao, Ying, Wang, Zinan, Tan, Hexin, Tang, Kexuan, Zhang, Lei
Biotechnology and bioprocess engineering 2015 v.20 no.4 pp. 677-684
Arabidopsis thaliana, RNA interference, apoplast, ascorbate oxidase, ascorbic acid, biosynthesis, breeding, galactose, gene overexpression, genetically modified organisms, humans, metabolic engineering, nutritive value
Vitamin C (L-ascorbic acid, AsA) is a compound which provides major nutritional value, both for plants and humans. In this study, three distinct metabolic engineering strategies, including overexpression of biosynthesis enzyme, suppression of catabolism enzyme and switching the sub-cellular localization of compartment enzyme, were employed to enhance the production of AsA in Arabidopsis thaliana. The results showed that (1) overexpression of L-Galactose-1-P Phosphatase (GalPPase) enhanced AsA content to 3.96 µmol/g FW, which was 1.6-fold more than that in their wild-type (WT) counterparts; (2) RNAi suppression of ascorbate oxidase (AO) resulted in a significant increase of AsA accumulation (0.86 µmol/g FW) in apoplast; (3) both mitochondrion-target and none-target overexpression of L-Galactose dehydrogenase (GalDH) did not significantly promote AsA production compared with WT (1.96 µmol/g), however a dramatic enhancement was observed following infiltration with L-galactono-1, 4-lactone (L-GalL), both in transgenic and WT plants. The best line produced AsA with the content of 3.90 µmol/g FW, which was about 2-fold of that in the untreated control (1.99 µmol/g FW). This study provides new strategies including GalPPase overexpression, AO suppression as well as L-GalL feeding for modern breeding aimed at stimulating the AsA content in plants.