L-Ascorbic Acid: A Multifunctional Molecule Supporting Plant Growth and Development

Table 2

Approaches to increase ascorbic acid content or redox state through increasing DHAR expression.

Species	Tissue	Subcellular location	Gene source	Fold increase in Asc	Fold increase in Asc redox state	Consequence of increasing DHAR expression	Reference
Tobacco	Leaves	Cytosol	Wheat	2.2 to 3.9	2 to 3	Increased GSH content and redox state; increased ozone tolerance; reduced ROS; reduced photoinhibition; embryo twinning	[11, 141, 146, 162, 178, 181]
Tobacco	Leaves	Cytosol	Arabidopsis	1.9 to 2.1	2.4 to 2.6	Enhanced tolerance to ozone, drought, and salt	[182]
Tobacco	Leaves	Cytosol	Arabidopsis	1.3	1.6	Enhanced tolerance to aluminum	[183]
Tobacco	Leaves	Chloroplast	Human	No change	2	Increased GR activity; lower GSH redox state; enhanced tolerance to low temperature and oxidative stress	[179, 180]
Tobacco	Leaves	Chloroplast	Rice	1.6	2.4 to 3	Increased GSH content; decreased GSH redox state; enhanced tolerance to salt and cold stress	[184]
Potato	Leaves	Cytosol	Sesame	1.5	Not reported	1.6-fold increase in Asc in tubers as well using 35S promoter	[185]
Potato	Leaves	Cytosol	Potato	1.6	1.6	1.2-fold increase in Asc in tubers as well using 35S promoter	[186]
Potato	Leaves	Chloroplast	Potato	1.4 to 1.5	1.4 to 1.5	No increase in Asc in tubers	[186]
Arabidopsis	Leaves	Cytosol	Arabidopsis	2 to 4.25	3 to 16	Increased GSH content and redox state; enhanced tolerance to high-light and high-temperature stress	[187]
Arabidopsis	Leaves	Cytosol	Rice	1.1 to 1.4	0.9 to 1.1	Enhanced tolerance to salt stress	[188]
Maize	Leaves	Cytosol	Wheat	1.8	1.3 to 1.4	Increased GSH content and redox state	[11]
Tomato	Fruit	Cytosol	Tomato	1.6	Not reported	No increase in foliar Asc content	[189]
Potato	Tubers	Cytosol	Sesame	1.1 to 1.3	Not reported	No change in foliar Asc content using the tuber-specific patatin promoter	[185]
Maize	Kernels	Cytosol	Wheat	1.9	1 to 4	Improved nutritive value of maize grain; increased GSH content and redox state	[11]
Maize	Kernels	Cytosol	Wheat	6	Not reported	Improved nutritive value of maize grain	[13]