In attention to the importance of forage plants and the necessity to use genetic resources and in
order to overcome the environmental stresses such as salinity, uniform grass pea seeds (landrace
of Maragheh) were selected and grown in hydroponic system. At 4-5 leaves stage, seedlings were
subjected to 200 mM salt stress for a period of 10 days. Sampling was done from the leaves and
roots of seedlings and it used to assess the antioxidant enzymes involving in defense mechanisms.
Evaluation of antioxidant enzymes in grass pea leaves showed that despite a significant increase
in catalase, total superoxide dismutase and guaiacol peroxidase, injury to the membranes has
been increased. Likely, the increased damage to membranes would be caused by lack of
significant increase in ascorbate peroxidase and isozyme of Cu/Zn-SOD. Because the low activity
of this enzymes led to inefficient implementation of Mehler cycle following by reduce efficiency
of xantophyll cycle and a change in Tylakoid status. Therefore, ROS production overcomes the
plant defense mechanisms leading to increased lipid peroxidation under salinity. Interestingly in
the root and under salt stress, the rate of damage to cell and organelle membranes was
significantly reduced compared with the control. It seems unexpected behavior of root may be
due to the changes in fatty acid compositions of the membranes structure