Environmental Engineering Reference
In-Depth Information
Table 2. (Continued)
Gene symbol
Donor
Acceptor
Gene functions
Elevated character
References
Crucial for Ascorbate
(AsA) regeneration
and essential for
maintaining a reduced
pool of AsA
Enhanced redox
state of ascorbate
and reduced levels
of malondialdehyde
Monodehydroascorbate
reductase (MDAR)
Avicennia
marina
Kavitha et al.
(2010)
Tobacco
Resistance to methyl
viologen and and
salt stress
Ascorbate peroxidase
(APX)
Primary H
2
O
2
scavenging enzyme
Populus
Tobacco
Li et al. (2009)
Primary H
2
O
2
scavenging enzyme;
the first enzyme in
the enzymatic
antioxidative pathway
Improved seed
longevity and
germination under
various
environmental stress
Ascorbate peroxidase
(APX), Superoxide
dismutase (SOD)
Tobacco
Tobacco
Lee et al. (2010)
Reducing H
2
O
2
and
organic hydro-
peroxides to water
and correspondingly
alcohols
Strong tolerance to
salt, H2O2, and
ABA treatment
Glutathione peroxidases
(GPXs)
Wheat
A. thaliana
Zhai et al. (2013)
Higher contents of
nonenzymatic
antioxidants
glutathione and
Ascorbate and
lower accumulation
of hydrogen peroxide
Primary H
2
O
2
scavenging enzyme;
the first enzyme in
the enzymatic
antioxidative pathway
Ascorbate peroxidase
(APX), Superoxide
dismutase (SOD)
Diaz-Vivanco et
al. (2013)
Plums
Plums
In higher plants, the ROS removal system includes ROS-scavenging antioxidant enzymes
and small non-enzymatic molecules such as ascorbate, glutathione, flavonoids, anthocyanines
and carotenoids (Türkan and Demiral 2009). The non-enzymatic molecules are able to donate
electron or hydrogen to scavenge free radicals (Jaleel et al. 2009). The antioxidant enzyme
system consists of superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase
(APX), glutathione peroxidases (GPX), glu tathione reductase (GR), catalase (CAT) and
ascorbate-glutathione cycle (Ashraf and Akram 2009). The SOD, APX and GR are reported
to scavenge H
2
O
2
in chloroplast and mitochondria, and the others are believed to be capable
of removing H
2
O
2
, neutralizing or scavenging free radicals (Karpinski and Muhlenbock
2007). Among them, SOD and CAT are the most efficient enzymes. Under salt stress, the
second metabolites increased more quickly than the increase of antioxidant enzyme activities
in
Swertia chirata
(Abrol et al. 2012).
The levels and contents of superoxide and hydrogen
peroxide can be decreased by most of the antioxidant obviously, so in many species the
antioxidant capacity is associated with salinity tolerance tightly. For example, the antioxidant
enzyme activities of SOD, APX and GR increased 10 to 18 times after salt stress in
P
.
Popularis
(Chen and Polle 2010). The correlation between antioxidant capacity and salinity
tolerance is being discovered in more and more species, containing cotton, citrus, foxtail
millet, purslane, sugar beet, pea and plantago (Türkan and Demiral 2009).
During the last few decades, engineering the genes of some antioxidant enzymes has been
employed to ameliorate plants exposed to stresses. By observing the changes of the related
genes expression level, transgenic plants were produced to probe the effects. Finally the
transgenic plants overexpression antioxidant enzymes such as SOD, CAT and APX displayed
elevated tolerance to oxidative stress (Türkan and Demiral 2009). The transgenic Arabidopsis
and L.
esculentum
possess a significant increase in salt tolerance with the overexpression of a
