Studies On Anti-TMV Activity Of Botanical-derivated VFB

Botanical-derivated VFB was a kind of anti-viral agent mainly from Portulacaoleracea and Glycyrrhiza, which was developed by Research and Development Center of Biorational Pesticide, Northwest A&F University. In this study, we took Nicotiana glutinosa and Nicotiana tabacum as the host material, and took tabocco mosaic virus(TMV) as the experiment virus, measured biological activity of VFB and researched on Physiological-Biochemical and histopathologic changes. The research results were as follows: VFB had the ability of inactivating TMV in vitro. When VFB was mixed with TMV and inoculated on the leaf of Nicotiana glutinosa after half hour, one hour and two hours by means of half-leaf speckle, the inhibition rate of necrotic local lesions was 44.41%, 55.62% and 64.43%, respectively. The inactivation effect of VFB and the inactivation time was positive relation, and the efficiency of VFB against TMV is higher than Virus A at the same dosage. VFB had the ability of inhibiting infectivity of TMV. The experiment results indicated that VFB, which was applied before inoculation, could depress the infectivity of TMV, and it could inhibit multiplication of TMV in a certain extent in Nicotiana glutinosa. The efficiency of 48h applied before inoculation was better than that of 24h, and the efficiency of inhibiting multiplication of TMV 24h after inoculation reached 36.15%. The indoor potted plant experiment displayed VFB had good protection and treatment to TMV in Nicotiana tabacum. The best application way was spraying plus pouring. On 14d and 21d after treatment, the efficiencies of protection were 75.00% and 51.11%, respectively, and the efficiencies of treatment reached 68.75% and 41.67%. It was higher than Virus A at same time. The effect of VFB treatment on the content of chlorophyll, total phenols, flavonoid, dissociative amino acid and MDA in Nicotiana tabacum was investigated. The results indicated that VFB could remarkedly increase the content of chlorophyll, total phenols, flavonoid and free amino acid compared with check, and the content of MDA was remarkably reduced than check. The effect of VFB treatment on the activity of POD, PPO and PAL in Nicotiana tabacum was investigated. The results showed that VFB could remarkedly increase the activity of POD, PPO and PAL. Through polyacrylamide gel electrophoresis(PAGE), the results indicated that VFB could induce Nicotiana tabacum to have new isoenzyme spectrum of POD and PPO compared with check. It was relation to the host's resistance against diseases. By means of ultrathin section methods, the ultrastructure of leaves infected by TMV, was observed under electron microscope. The results of electron microscopic observation showed the ultrastructure of leaves were altered partly. After VFB treatment, TMV particle break up in large number, and TMV coat protein encapsidation was affected obviously, and the disorganization of chloroplast and mitochondrion was mitigated, and VFB induced tobacco to produce a great deal of osmiumphilic bodies and velum bodies. That above indicated that VFB had good protection and treatment to tobacco mosaic disease. VFB might have the ability of inactivating TMV in vitro, and it could make TMV particle break up in large number, and affect the capsid protein recombination, so inhibit the infectivity of TMV. VFB could remarkably increase the content of chlorophyll, total phenols, flavonoid and free amino acid, and reduce the content of MDA, and increase the activity of POD, PPO and PAL, and induce tobacco to have new isoenzyme spectrum of POD and PPO. That above showed that VFB could induce the host to have resistance against diseases, and strengthen its antiviral capability.