Role Of NO In Signal Pathway Of Defense Response Induced By Mechanical Wounding In Pea Seedlings

NO and JA are important signal substances in plants. It have an important theoretical practical significance to confirm NO signal effect in the damage stress and understand the produce pathway of NO and JA within plant body under damage stress and the relationship between them. This study use the pea seedling as test material treatment by Mechanical damage and combining with pharmacological method First researched the signal function of NO in the defense responses of pea seeding.meanwhile analyzed under mechanical injury the dynamics change of NO and JA content and the production pathway within pea seedling leaves.Finally use pharmacological method,deeply analyzed the relationship of NO、JA and active oxygen in the signal pathway of mechanical injury induced pea seedling defense reaction form. The main results are as follows:1. After mechanical injury the lignin content and the active of PAL and PI increased within the pea seedling leaves. Exogenous NO could induced pea seedling leaves produced the same defense change as mechanical damage conduct. That is lignin content and PAL active increased, after cleared away NO the defense reaction was controlled NO is no significant effect on the PI active within the pea seedling leaves.2. The NO content of normal pea seedling in leaf is little, while it would accumulating rapidly after mechanical damage and appear to be one low and one high bimodal trend during the whole process of stress. After the damage, the activity of NOS does not change rapidly[2.08～2.76 μmol NO/(mg Pr·h)]. In the preliminary stage(0～1h) the activity of NOS rise up a little bit. Later it decrease less than the control. After 12h have another raised until it reaches the peak at 24h. While the NR decrease during 0～1h after the damage, and start to increase rapidly after 1h. After 24h it reaches the peak. From the above changes speculated the NO accumulate may together NOS and NR pathway after wounding,and wounding later period the NR pathway may have the main contribution.3. Normal pea seedling leaves contain a small amount of JA, its content increase quickly after injury treatment,1h and 24h appear two peaks,obviously one high and one low. linoleic acid and linolenic acid,biosynthesis substrates of JA, in the whole process of stress present two peak, one high and one low,appear in the 1h and 36h respectively.The key enzyme of biosynthesis LOX’s activity appear two peak, one low and one high.which suppose that both substrate and catalyzing enzyme take part in the JA synthetise induced by mechanical injury,and the synthesis key enzyme LOX may have the main contribution.4. Adopt the method of pharmacology,the further analysis to the relationship between JA and NO in the damage defense reaction in pea seedling,it show that the NO content and the NOS and NR activity have rised in the pea seedling leaves with exogenous JA,after disposed by LOX inhibitor(NDGA),obviously inhibit the produce of NO which induced by wounding;disposed by NO generator,the JA content have no obviously change in the pea seedling leaves. Content increased when cleaned up NO. It is conjectured that signal JA before then the signal NO in the injury signal transduction pathways.5. Analysis the relationship between NO in pea seedling leaf and Reactive oxygen species by the pharmacological method,it show that NO can improve the activity of SOD,POD,CAT and APX. After reduced mechanical injury management H2O2 and O2-accumulated,and then reduced the accumulation of MDA that is the production of membrane lipid peroxidation.