Genome Structure And Biological Function Research Of DsRNA Virus In Phomopsis Vexans Of PvCS-1

The Phomopsis blight of eggplant,also known as brown rot,is a serious fungal disease.Phomopsis vexans was the pathogen of this disease.With the continuous spread of pathogenic bacteria in the global scope,various degrees of harm have appeared in the country.The use of weak viral strains can cause the decline of the pathogenicity of the pathogen population,which has become another approach for the biological control of fungal diseases（Li Tao,2008）.It is of great theoretical and practical significance to seek new control approaches for the effective control of the Phomopsis blight of eggplant.At present,a variety of pathogenic fungi have been found that can cause the decline of pathogenicity of plant pathogens,but there are few reports on virus-related fungal viruses in Phomopsis vexans,which provides a new method for the biological control of Phomopsis vexans in eggplant by mining and screening fungal viruses with biocontrol potential against the Phomopsis blight of eggplant.In this study,PvCS-1 as the material,the relationship between genome structure and biological function research of ds RNA Virus in Phomopsis vexans of PvCS-1 was analyzed.The main results are as follows:（1）The P.vexans strain PvCS-1 was isolated from a diseased the Phomopsis blight of eggplant.There was a ds RNA virus in PvCS-1 strain,and four ds RNA bands were obtained,which were named as ds RNA-1,ds RNA-2,ds RNA-3 and ds RNA-4 according to their molecular weight respectively.ds RNA-1 was Phomopsis vexans Endornavirus 1（PvEV1）.ds RNA-2 was Phomopsis vexans Victorivirus 2（PvV2）.ds RNA-3 was Phomopsis vexans victorivirus L1（PvVVL1）.ds RNA-4 was Phomopsis vexans partitivirus 1（PvPV1）.（2）There was no significant difference between PvCS-1 and PvCS-T in colony morphology,hypha growth rate and other biological phenotypes,but the fungal virus in PvCS-1 could affect the pathogenicity of host fungi to purple eggplant fruits,which indicated that the mycoviruses contained in PvCS-1 had a weak virulence,but did not affect the growth phenotypes of host fungi.（3）The ds RNA in PvCS-1 was eliminated by the protoplast virus-free technology,and a completely virus-free strain PvCS-T was obtained.PvCS-1 and PvCS-T strains with the same genetic background showed no significant differences in biological phenotypes,such as colony morphology and mycelial growth rate,but the difference in pathogenicity was significant between the two strains,which indicated that mycovirus contained in PvCS-1 had a weak virulence,but did not affect the growth phenotypes of host fungi.In order to further explore the characteristics of attenuant toxicity,five kinds of agents were tested for PvCS-T and PvCS-1.In order to further explore the influence of fungal viruses on host biological traits,five kinds of bacteriostatic rates of PvCS-T and PvCS-1 were tested.The experimental results showed that the fungal viruses contained in PvCS-1 strain had no significant difference in the influence of host fungi on the resistance to fungicides.Among the five agents,25%pyrazolium ester suspension had the strongest inhibitory effect on Phomopsis vexans,followed by 25%propiconazole emulsion,6%oligosaccharide water,25%oligosaccharide ethicin microemulsion and 10%prothiazole suspension.The inhibition effect of 25%pyrazolate suspension on the mycelial growth of completely virus-free strain PvCS-T and the original strain PvCS-1 was expressed by the toxicity regression equation and EC₅₀respectively.The EC₅₀ of PvCS-T was 0.936 mg·L^-1,and the EC₅₀ of PvCS-1 was1.016 mg·L^-1.On this basis,the next step of greenhouse potting and field control experiments were carried out.