Physiological response of leaves and roots of Leymus chinensis under drought and salt stress

The growth of Leymus chinensis was severely restricted by the arid climate and salinized land in north of China. This test contrasts physiological responses of roots and leaves of L. chinensis under stress, to identify the effects on, and differences between, roots and leaves of L. chinensis by simulating different drought and salt conditions. The benefit of this study is to provide a theoretical basis for enhanced salt tolerance and drought tolerance in L. chinensis. Drought stress and salt stress were respectively simulated by different concentrations of PEG solution and NaCl solution. We discuss the activities of antioxidant enzymes (APX, CAT, and POD) and diversification of soluble protein content in the roots and leaves of L. chinensis. Result: Under mild salt stress (100 mmol·L-1), L. chinensis mainly eliminated the ROS through APX of the leaves, and the site of osmotic regulation is mainly in the leaves; under moderate salt stress (200, 300 mmol·L-1), the roots and leaves eliminated ROS by increasing activities of POD and CAT, and the roots mainly improved activity of POD, and the leaves mainly enhanced activity of CAT; under severe stress (400 mmol·L-1), APX of the roots was significantly increased, while the leaves were able to resist damage from ROS by increasing POD and CAT activities, and the location of osmotic regulation also changed from leaves, to roots and leaves. In the early stage of drought stress (20%), L. chinensis mainly relied on APX of roots and leaves and CAT of leaves to eliminate ROS. With the stress increase, activities of APX and CAT in roots were increased to resist the damage from ROS, and the activity of POD in roots and leaves kept decreasing, The location of osmotic adjustment was mainly in leaves.