Studies On Signal Substance In The Formation Of Induced Populational Resistance Of P.Simonii×P.Pyramibalis C.v.Seedlings

P.SimoniixP.Pyramibalis c.v was used as experiment material in this study. In order to discuss the physiological differences in induced defense response by mechanical injury and herbivory injury and explore the production mechanism of induced defense substance between plants, three treaments including mechanical injury by hemostat, feeding and exposure to Methyl Jasmonic acid were applied to the plants.At different time after treatment,induced phenolics in the wounded plant and the neibouring intact plant were measured as well as some enzymes including POD,PPO and LOX,which may influence the phenolics production.The results showed that significant differences exited in change of phenolics content and enzymes activity in the treated plants between mechanial injury and herbivory injury suggesting that plant could recoganized the various stress, which stimulated distinct defense systems. The active components in the mouth secretions of insect and continuous injury of insect on leaves were the main causes. The content of phenolics in induced leaves also varied obviously, and in response to different treatments the change differed greatly, which demonstrated signal transduction between woody plants and induced various signal molecules among differet treatments.Using the acknowledged signal molecule in herbage-MeJA, the phenolics, PPO and POD in P.SimoniixP.Pyramibalis c.v plants after exposure exhibited evident change. This provided strong evidence for MeJA acting as the interplant signal of woody plants.There are differences exited in change of phenolics content and enzymes activity in the treated plants between injury and expose to MeJA suggest signals is multiple.JA pathway was an important signal transduction pathway in plant,which was involved in the synthesis of a great amount of defense substances. Since LOX was the key enzyme of this pathwasy, its change of activity in the leaves after three treatments was tested. It was been found that three treatments all could enhance LOX activity, which showed that the JA pathway was stimulated, subsequently heightened resistance of theplant. The relationship between the variation of LOX and PPO,POD was investigated too, which indicated the LOX acted on the upstream of the PPO and POD..The synthesis of resistance substance and the variation of enzyme in treated plants resulted from gene expression and regulation. In order to separate and clone the genes indued by mechanical damage,Rapid subtraction hybridization(RaSH) was also used to hybridize cDNA of the treated P.SimoniixRPyramibalis c.v plant at 24h after injury and the control cDNA in this study. The hybridized product was tranfer into top10, and according to the PCR we could preliminarily confer that the differential expression of genes exited. This part of expriment was under way.