| The mechanism of plant defense responseinduced by to wounding was investigated in pea seedlings (Pisum sativum L.). The signal functionof and the signal transduction of both jasmonic acid (JA) and hydrogen peroxide (H2O2) as signal molecule and the signal transduction process were attracted more attention also studied. The results showed as follows:Pretreatments of both the wounding and exogenous jasmonic acid (JA) treatment could induce induce burst of active oxygen species and enhance enhancement of the activities of both phenylmethylsulfonyl fluoride (PAL) and poly-phenol oxidase (PPO), the key enzymes of JA biosynthesis, in the pea leaves on one hand, and on the other hand obviously ; increase the activity activities of antioxidant enzymes, thus The membrane lipid peroxidation thus decreased and the oxidative damage also reduced decreased. JA in JA of suitable concentration (1-10 μmol/L) induced defense response, however whereas, JA of JA in high concentration (100 μmol/L) resulted incaused unbalance of metabolism of active oxygen species metabolism and promoted enhancement of lipid peroxidation.The change of subcellular localization of jasmonic acid (JA) was investigated in the leaves of pea seedlings in response to wounding by immunogold electron microscopy technique. The results showed that a large number of JA visualized by immunogold particles were distributed in the cell wall and chloroplaste of the mesophyll cells, and a few in the nuclei and cytoplasm. In phloem, most of immunogold particles were found in the cell wall of the SE-CC complex, whereas little immuno-signal was observed in the xylem. In pea seedlings response to wounding, a rapid accumulation of JA wasobserved firstly accumulated rapidly in the the mesophyll cells of the wounded leaves and subsequentlyfaster than in either these of the unwounded leaves adjacent to the wounded ones or these of the inferior leaves far from the wounded ones in contrast. However, similar timings of JA change were found in between the SE-CC complex of the wounded leaves and of unwounded ones. Additionally, the rapid activation. The activity of both lipoxygenase (LOX) and allene oxide synthase (the critical enzymes synthesizing JA) increased, which was later than was preceded by the accumulation of JA. So it is suggested that the compartmentalized enrichment of JA in pea leaves response to wounding might be attributed to therelocation and transport of among the tissues s The timings and compartmen of hydrogen peroxide (H2O2) triggered by either wounding or exogenous JA were by the DAB tissue staining, CeCl3 cellular chemistry staining and TiCl4 staining. The results showed, wounding and JA treatment could also induced the H2O2 systemic burst, and both the raisingthe burst time and the changes of the contentsimilar in during different wounding treatmentin were almost the same, simulated Diphenylene iodonium (DPI), an inhibitor of NADPH oxidase, Assay of H2O2 subcellular location revealed that H2O2 in response to wounding and exogenous JA predominantly accumulated in plasma membrane, cell wall and apoplasmic space, thus, the plasma membrane NADPH oxidase perhaps was the critical enzyme leading to H2O2 burst. To investigate the mechanism of the formation of H2O2, theactivity of NADPH oxidase located in the plasma membrane was determined. The activity of NADPH oxidase could be induced by either wounding or JA treatmensynchronouslyt, and the changes of the activity was synchronous with the oxidative burst, the Correspondingly, the increase of PAL activity triggered by wounding or JA orwas inhibited when H2O2 was eliminated, which showed the activation of NADPH oxidase and the generation of H2O2 participated inthe increase of the activity that of PAL induced by wounding or JA treatment. The generation of H2O2 that triggered by wounding or JA treatment also related to Ca2+ fluxion CaM, reversible the phosphorylationand process. The activity of proton pump could also be triggered by either wounding or JA, which may play a role in the upstream of the active oxygen burst.The...
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