The changes of malondialdehyde (MDA), H2O2, and O2-. content, or the activities of superoxide dismutase (SOD), catalase (CAT), ascrobate peroxidase (APX), peroxidase (POD), phenylalanine ammonia lyase (PAL), and polyphenol oxidase (PPO) in pea seedlings (Pisum sativum L.) under wounding and treatment of exogenous jasmonic acid (JA) were investigated. The results showed that the activities of both phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO) were significantly increased by wounding and application of JA. The metabolism of reaction oxidative species (ROS) was enhanced, especially O2-. and H2O2 appeared to rapidly increase. The activities of antioxidant enzymes such as SOD, CAT, APX and POD were also increased. Treatment of JA of 1 or 10 μmol L-1 could effectively induce plant defense response, and thus decrease the peroxidation of cell membrane lipid. However, high concentration of JA (100 μmol L-1) resulted in unbalance of metabolism of ROS and promoted the peroxidation of cell membrane lipid. We thus suggested that JA, under the suitable concentration, could induce defense response of pea seedlings to wounding.
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