Abstract: The effects of wounding and exogenous-applied jasmonic acid (JA) on the membrane lipid peroxidation were investigated in pea seedlings (Pisum sativum L.). The results showed that the activities of both phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO) significantly increased by wounding and application of JA. The metabolism of reaction oxidative species (ROS) was enhanced, especially O2-·and H2O2 increased rapidly. The antioxidant enzymes such as supiroxide dismutase (SOD), catalase (CAT), ascrobate peroxidase (APX) and peroxidase (POD) were also activated. Pretreatment of JA of 1-10 μmol·L-1 could effectively induce plant defense response, and thus decrease the level of cell membrane lipid peroxidation. However, high concentration of JA (100 μmol·L-1) resulted in unbalance of metabolism of ROS and promote lipid peroxidation. It is concluded that JA, under the suitable concentration, can induce pea seedlings defense response to wounding.

Key words: Pisum sativum L., Mechanical wounding, JA Membrane lipid peroxidation, Defense response