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Table 2 Transgenic approaches for overproduction of L-ascorbate in plants

From: Role of L-ascorbate in alleviating abiotic stresses in crop plants

Enzyme Target plant Gene Gene source Type of genetic manipulation Ascorbate content Phenotypic change Reference
GDP-l-galactose phosphorylases Tomato GGP/ VTC2 Actinidia chinensis Overexpression 3.0–6.0-fold increase in fruits Bulley et al. 2012
Strawberry    Overexpression 2.0-fold increase in fruits
Potato   Potato/Arabidopsis Overexpression Up to 3.0-fold increase in tuber
GDP-mannose pyrophosphorylase Potato GMPase Potato Antisense downregulation 0.88–1.44-fold reduction in leaves Dark spots on leaf veins and stems Keller et al. 1999
     0.56-fold reduction in tubers Early senesce
GDP-Mannose 3’,5’-epimerase Tomato SlGME1 Tomato Overexpression Up to 1.42-fold increase in leaves Improved tolerance to various abiotic stresses such as cold, salt and MV Zhang et al. 2011
     Up to 1.60-fold increase in fruits  
  SlGME2   Overexpression Up to 1.37-fold increase in leaves  
     Up to 1.24-fold increase in fruits  
L-galactose guanyltransferase Tobacco GalT Kiwifruit Transient expression (leaves) Up to 3.0-fold increase Laing et al. 2007
L-Galactose dehydrogenase Tobacco L-GalDH Arabidopsis Overexpression No change Gatzek et al. 2002
Arabidopsis   Arabidopsis Antisense downregulation 0.7-fold decrease  
L-galactono-1,4-lactone dehydrogenase Rice L-GalLDH Rice RNAi 0.6–0.87-fold decrease Slow plant growth rate and poor seed set Liu et al. 2011
   Rice Overexpression Up to 1.48-fold increase Increased NPR and higher seed set
Tomato SlGalLDH Tomato RNAi No change Slow plant growth rate Alhagdow et al. 2007
      Strong reduction in leaf and fruit size
Rice L-GalLDH Rice RNAi 0.3– 0.5-fold decrease Slow growth rate, reduced tiller number, decreased NPR and premature senescence Liu et al. 2013b
L-gulono-c-lactone oxidase Arabidopsis GLOase Rat Overexpression Up to 2.0–3.0-fold increase Radzio et al. 2003
Lettuce GLOase Rat Overexpression 4.0–7.0-fold increase Jain and Nessler 2000
Tobacco    Overexpression Up to 7.0-fold increase
Tomato GLOase Rat Overexpression 1.5-fold increase in fruits Enhanced tolerance to MV, NaCl, and mannitol Lim et al. 2012
Potato GLOase Rat Overexpression Up to 1.41-fold increase Enhanced tolerance to MV, NaCl, and mannitol Hemavathi et al. 2010
D-galacturonic acid reductase Arabidopsis GalUR Strawberry Overexpression 2.0–3.0-fold increase Agius et al. 2003
Potato GalUR Strawberry Overexpression 1.6–2.0-fold increase Enhanced tolerance to MV, NaCl, and mannitol Hemavathi et al. 2009
Tomato (Hairy Roots) GalUR Strawberry Overexpression 2.5-fold increase High growth rate Wevar Oller et al. 2009
Monodehydroascorbate reductase Tomato LeMDAR Tomato Overexpression Up to 1.18-fold increase Enhanced tolerance to temperature (low/high) and MV stresses Li et al. 2010
      High NPR
    Antisense downregulation Up to 1.3-fold decrease Susceptible to various abiotic stresses
Tomato MDAR Tomato Overexpression 0.7-fold reduced in fruits Haroldsen et al. 2011
     No change in leaves  
Dehydroascorbate reductase Tomato DHAR Tomato Overexpression 1.6-fold increase in fruits Haroldsen et al. 2011
     No change in leaves  
Maize (Kernels) DHAR Wheat Overexpression 6.0-fold increase Naqvi et al. 2009
Maize DHAR Wheat Overexpression Up to 1.8-fold (leaves) and 1.9–fold (kernels) increase Chen et al. 2003
Tobacco DHAR Wheat Overexpression 2.2–3.9-fold increase Chen et al. 2003
Tobacco DHAR Rice Overexpression Up to 1.6-fold increase Enhanced tolerance to salt and cold stresses Le Martret et al. 2011
Tobacco DHAR Human Overexpression (chloroplasts) 1.1-fold increase Increased SOD and APX activities in conjunction via triple gene construct Lee et al. 2007
      Increased tolerance to MV and NaCl induced stress
Potato DHAR Sesame Overexpression 1.1–1.3-fold increase in tuber with patatin promoter Goo et al. 2008
    Overexpression 1.5- and 1.6-fold increase in leaves and tuber respectively, with CaMV35S promoter 1.5- and 1.6-fold increase in leaves and tuber respectively, with CaMV35S promoter
Potato StDHAR1 Potato Overexpression (Cytosol) Up to 0.69-fold increase in leaves Qin et al. 2011
     Up to 0.29-fold increase in tubers  
     Up to 0.50-fold increase in leaves
  StDHAR2   Overexpression (Chloroplast) No significant change in tubers  
Arabidopsis DHAR1 Rice Overexpression > 1.4-fold increase Enhanced tolerance to salt stress Ushimaru et al. 2006
Arabidopsis DHAR Arabidopsis Overexpression 2.0–4.25-fold increase Enhanced tolerance to high–light and high–temperature stress Wang et al. 2010
Myoinositol oxygenase Arabidopsis miox4 Arabidopsis Overexpression 2.0–3.0-fold increase Lorence et al. 2004
  1. MV, methyl viologen; NPR, net photosynthetic rate; RNAi, RNA interference.