Responses Mechanism Of Antioxidant Defense System Of Artemisia Frigida Willd. To Mechanical Damage

Artemisia frigida Willd.is perennial semishrub in Asteraceae, it plays an irreplaceable role in maintaining grassland regeneration and improving ecological environment in the North. In order to investigate the responsing mechanism of antioxidant defense system of A. frigid to grazing, and explain the reasons for maintaining the dominant of the population of A. frigida under continuous grazing, we use artificial mechanical damage(light, moderate and heavy) ways to deal with the potted A. frigida. Foliage, and determinate the contents of growth related substances, ROS generation status, antioxidant enzyme activity and As A-GSH cycle and other related indicators under mechanical damage of A. frigida. Foliage, and analyze the response mechanism of antioxidant defense system of A. frigida to mechanical damage, Concluded as follows:(1) Under mechanical damage stress, protein and chlorophyll content of A. frigida. leaves descend;in the treatment of light or moderate, the material contents of glucose, fructose, amino acids show upward trend compared with the control. After the damage treating for 24 h, glucose, sucrose, amylum and chlorophyll contents of A. frigida leaves were returned to control levels, the trend of A. frigida root growth-related substances below which of the leaves. It illustrate that A.frigida can maintain osmotic balance of cells by increasing the contents of osmotic substances, and some growth-related substances of A. frigida can be restored to the control level in a relatively short period of time after damage. This explains that the A. frigida has a strong ability to adapt to damage.(2) With the increasing mechanical damage strength, O2?- and H2O2 contents of A. frigida leaves increase, and the content of MDA increase; due to stimulation of mechanical damage, activity of antioxidant defenses enzyme in A. frigida gradually enhance; With the increasing of mechanical damage, activity of As A-GSH cycle-related enzyme enhanced. By maintaining the regeneration of non-enzymatic antioxidants As A and GSH, the relative balance between generation and elimination of H2O2 could be maintain; The changed trend of various antioxidation indicators under the mechanical damage of A. frigida roots similar to which of the leaves, but slower than the leaves; and this show that A. frigida under the concerted action of the enzyme system and non-enzyme system could make the increase of O2?- and H2O2 contents slow down significantly, and effectively eliminate ROS damage produced by mechanical damage; A. frigida.has strong antioxidant ability.(3) 6 h after the mechanical damage treatment, ROS levels and MDA contents increased rapidly; with the time continued, the activity of antioxidant enzymes and As A-GSH-related enzyme rise in the first stage, and then decrease; due to effect of mechanical damage, antioxidants As A and GSH levels decrease, and because of As A-GSH cycle enzymes, antioxidants can recovered 24 h after treatment; rangeability of A. frigida roots be inferior to the leaves in the different time points; under the synergistic action of the enzyme systems and non-enzymatic systems, 24 h after treatment, ROS and MDA levels basically returned to control levels. This illustrates the A. frigida antioxidant defense system can eliminate ROS which is generated by mechanical damage quickly and effectively, so that protect A. frigid from the damage of ROS.