Phenoloxidase Mediated Immune Defense Mechanism In Diamondback Moth Ondiamide Insecticides Resistance

Subjects in this study,we selected five strains of diamondback moth,which were susceptible strain(S)?chlorantraniliprole resistant strain(R_f)?flubendiamide resistant strain(R_h)Baiyun filed population(R_b)and ZengCheng filed population(R_z).Through their determination of the phenoloxidase activity,the mRNA expression level of PxPPO1 and PxPPO2 and the relative expression of PPO1 and PPO2.preliminary study of the mechanism of phenoloxidase mediated immune defense how to effect on the resistance of diamondback month.At the same time,effect of phloridzin and other three kinds of chemical compounds on the phenoloxidase activity were determined.And Determination of the inhibitory effect and the inhibitory constant of the phloridzin on the phenoloxidase.In order to further study the effective inhibitors of insect phenoloxidase.The main contents are as follows:(1)By measuring the vitality of of phenoloxidase activity of five strains of diamondback moth.The result showed that the phenoloxidase activity of R_f?R_h?R_z and R_b resistant strains are higher than susceptible strain.(2)Real-time quantitative PCR was used to determine the mRNA expression level of PxPPO1 and PxPPO2.The result showed that the mRNA expression level of PxPPO1 and PxPPO2 of resistant strains are higher than susceptible strain.Determination of the relative expression of PPO1 and PPO2.Compared with the susceptible strain,the relative expression of resistant strains are higher.(3)Determination of the effect of three chemical compound on phenoloxidase activity.The result showed that when the concentration of three chemical compound was higher than0.4 mmol/L,three chemical compound had inhibitory effect on the enzyme activity of Phenoloxidase.And the trihydroxy-glycoside have the strongest inhibitory effect.(4)Determination of the inhibitory effect and the inhibitory constant of the phloridzin on the phenoloxidase.The result showed that the inhibition mechanism is competive,which indicates that the binding of the substrate to the compound and the enzyme molecule is competitive.And the inhibitory constant of the phloridzin(K1)was 12.53mmol/L.