Endogenous ABA as a Hormonal Intermediate in the Salicylic Acid Induced Protection of Wheat Plants Against Toxic Ions - Salicylic Acid: Plant Growth and Development - page 131

Fig. 10 The effect of
pretreatment 3-day-seedlings
with 50 lM SA or initially
with 5 mg/l fluridone alone
during 3 h and then mix
fluridone with SA for 24 h on
(a) WGA and (b) proline
content in 4-day wheat plants
under salinity. Mean data of
three independent replicates
and their SEs are presented

(a)

2,4 Control

2% NaCl
(SA)+2%NaCl
(FL+SA)+2%NaCl

1,8

1,2

0,6

0 2 4 6 8

(b)

Control 2%NaCl

2

(SA)+2%NaCl (FL + SA)+2%NaCl

1,5

1

0,5

9 24

Time, h

which make an important contribution to the protection of plants against oxidative
burst caused by salinity (Bezrukova et al. 2008 ; Hara 2010 ). The pretreatment of
seedlings initially with fluridone and then with a mixture of fluridone and SA
completely prevented the SA-induced increase in the level of ABA under salt-
stress conditions.
At the same time, attention is drawn to the fact that the joint fluridone pre-
treatment with SA although greatly reduced, but not completely prevented the
increase in WGA and proline content in seedlings subjected to salinity (Fig. 10 ).
Similar results were obtained during the study of the activity of antioxidant
enzymes. Salinity induces a fast increase initially in activity of SOD followed by
peroxidase in wheat seedlings (Fig. 11 ), which is a typical plant response to stress-
induced enhancement of ROS production (Jaspers and Kangasjarvi 2010 ). Stressed
plants pretreated with SA are characterized with a significantly lower activity of
antioxidant enzymes as compared to untreated plants (Fig. 11 ), which is likely to
be due to the lower production of ROS in the plants (Shakirova 2007 ). This is
associated with the fact that SA-treatment itself causes a balanced increase in
production of ROS and activity of antioxidant enzymes (Fig. 3 ), sufficient for
effective neutralization of salt-induced oxidative burst (Shakirova 2007 ).
These results support the belief of a key role of endogenous ABA in the
regulation of investigated protective components in the plants pretreated with SA.
This notion is supported by 50 % decline in the level of MDA in comparison with
the plants untreated with SA under salt stress (Fig. 12 a).