Exogenous application of phytoprotectants in legumes against environmental stress - Legumes Under Environmental Stress: Yield, Improvement and Adaptations - page 179

in response to Cd stress, while the activities of CAT,
MDHAR, DHAR and GR were sharply decreased.
Exogenous application of Pro (5 mM) and GB (5 mM)
resulted in an increase in GSH and AsA contents, main-
tenance of a high GSH/GSSG ratio and increase in the
activities of APX, DHAR, MDHAR, GR, GST, GPX and
CAT compared to control and mostly also Cd-stressed
plants, with a concomitant decrease in GSSG, H 2 O 2 and
MDA contents. These authors suggested that both Pro
and GB had a protective action against Cd-induced
oxidative stress in V. radiata seedlings. Hossain et al.
(2011) studied the effect of exogenous Pro and GB in
mitigating salt stress in V. radiata seedlings. Subjecting
the seedlings to 48 h of salt stress (200 mM NaCl)
resulted in sharp increases in lipid peroxidation and
H 2 O 2 content. Salt stress altered antioxidant metabo-
lism, which was revealed by increases in GSH and GSSG
and a decrease in AsA content. But the antioxidant
enzymes responded differently under salt stress. The
activities of MDHAR, DHAR and CAT decreased mark-
edly upon exposure to salt stress, whereas the activities
of GR, GPX and GST increased in response to salt stress.
However, these activities were not sufficient to protect
against salt stress-induced damage. The application of
exogenous Pro and GB caused significant increments
of the activities in salt-stressed seedlings, which resulted
in increased levels of AsA and GSH and reduced the
oxidative damage as indicated by decreased levels of
MDA and H 2 O 2 . The results of this study (Hossain et al.,
2011) prompted the suggestion that upregulation of
antioxidant defence by Pro and GB could confer salt
stress tolerance in V. radiata . Rezaei et al. (2012) grew
soybean plants supplemented with exogenous GB (2.5,
5, 7.5 and 10 kg ha −1 ) in saline soil (11.1 dS/m). The
uptake of Na + was decreased with the addition of GB in
salt-stressed plants. Glycine betaine application also
increased the number of lateral branches and pods per
plant, while no difference was observed in seed number
per pod. Exogenous GB was also able to increase the
1000-grain weight in salt-stressed plants. However, the
impact of GB on 1000-grain weight was cultivar-, dose-
and time-dependent. When V. faba was grown under
water-deficit conditions, plant height and root length,
root fresh weight, shoot fresh weight, root dry weight,
shoot dry weight, total soluble carbohydrates, chl a and
b , and activity of POD and CAT were all strongly
depressed with a concomitant increase in MDA content
(Ali et al., 2013). However, application of Pro improved

all growth characteristics by improving Pro, total soluble
carbohydrate (TSC) and photosynthetic pigments as
well as the activities of CAT and POD. These results indi-
cated that application of Pro helped the plant to restore
the physiological processes altered by water stress
(Ali et al., 2013). Taie et al. (2013) found physiological,
biochemical and anatomical attributes were enhanced
in seawater-treated Vicia faba plants when the seeds
were pretreated with Pro. When 16-day-old plants were
irrigated with seawater for 50 days they exhibited reduc-
tions in all growth parameters (plant height, number of
leaves and shoot dry weight per plant), photosynthetic
pigments (chl a , chl b and carotenoids), total carbohy-
drate, contents of P, Ca 2+ , K + and K:Na ratio compared to
controls. Increasing seawater stress also led to increases
in total phenolics, free amino acids, Pro and soluble car-
bohydrate as well as values of N, Na + , and Cl − . On the
other hand, the plants grown from Pro-pretreated seeds
showed salt tolerance reflected by improved growth
parameters, photosynthetic pigments, soluble carbohy-
drate and total carbohydrate and decreased Na + and
Cl − (Taie et al., 2013). The beneficial effect of foliar
applied Pro (20 mM) was found to protect against Cd
stress in C. arietinum as reported by Hayat et al. (2013).
Foliar treatment of Pro increased the plant growth.
Exogenous Pro also increased the photosynthetic attrib-
utes and yield characteristics in the Cd-stressed plants.
Moreover, the activities of antioxidative enzymes were
also increased when the plants were supplemented
with Pro.

11.4.3 polyamines
Polyamines (PAs) are low-molecular-mass aliphatic
amines and organic polycations found as three different
forms, viz. diamine putrescine (Put), triamine spermi-
dine (Spd) and tetraamine spermine (Spm), which are
involved in various processes such as cell proliferation,
somatic embryogenesis, seed germination, growth, mor-
phogenesis, differentiation, development of flowers and
fruits and programmed cell death (Hasanuzzaman et al.,
2014d).
In P. vulgaris , exogenous Put treatment (10 μM)
improved the germination and growth of plants grown
in saline soil (1% NaCl) (Zeid, 2004). The germination
percentage of Put-treated seeds increased under salinity
stress, which was associated with the activation of amy-
lase and protease enzymes during germination. The rise
of the K + /Na + ratio in shoots of Put-treated seedlings