The relationship of H2O2 and jasmonic acid (JA) in wound-induced defense response was investigated in the leaves of pea ( Pisum sativum L.) plants. The results showed that both wounding and JA treatment led to a significant increase in activities of plasma membrane NADPH oxidase and phenylalanine ammonialyase. However, such an increase was blocked by the pretreatment with plasma membrane NADPH oxidase inhibitors, Oscavengers, or H2O2 scavenger, implying that H2O2 functions downstream of JA. Furthermore, wounding treatment activated two key enzymes of JA biosynthesis, lipoxygenase and allene oxide synthase, while JA biosynthetic inhibitors impaired the wounding-induced H2O2 burst. Thus, it is suggested that H2O2 burst depends on JA production in plant wounding response. [ABSTRACT FROM AUTHOR]