The Separation And Identification Of And The Impact On Their Host Of DsRNA Viruses In Magnaporthe Oryzae

Magnaporthe oryzae,a worldwide phytopathogenic fungus,is one of the three major diseases of rice which is difficult to control and causes significant loss every year.At present,the prevention and control of rice blast mainly depend on chemical control and breeding of disease-resistant varieties.However,because of the emergence of drug resistance and the population diversity of M.oryzae,the prevention and control of rice blast become less effective.Mycoviruses widely spread in the fungal kingdom.The interaction of Mycoviruses with the host may have an impact on host phenotype,such as virulence,growth rate and production of pigments.However,the use of decline virulence-associated virus controlling plant fungal disease provides a potential application.In this study,we screened the presence of mycoviruses in M.oryzae strains using the CF-11 cellulose binding method method and did identified a mycovirus in M.oryzae strain GD45.The analysis results of biological characteristics with a virus-cured strain and a dsRNA-carried strain showed that mycoviruses in the strain GD45 can cause abnormal phenotype.Get the results as follows:1)we screened the presence of mycoviruses from a collection of 60 M.oryzae strains using the cellulose chromatography method and found that 16 strains harbored dsRNAs.The rate of infection reached 23.3%,This result showed that mycoviruses widely spread in the M.oryzae strains.2)The dsRNAs in the strain GD45 were extracted and purified.After gel electrophoresis detection at least three bands about 3kb were found.After sequencing,the analyses of dsRNA genome results showed that the genome of three dsRNA molecules encodes the RdRp,capsid protein,and a putative protein respectively.Those dsRNAs,by establishment of phylogenetic trees,belong to genus Chrysovirus.3)A virus-curing isolate was obtained from the dsRNA-infected strain GD45 by virus-curing methods of high temperature-ribavirin combination.The results of the comparison of colony morphology,growth rate and pathogenicity showed that the dsRNA can cause host abnormal phenotype.The experimental results indicate that the debilitated pathogenicity strain of GD45 is related to dsRNA viruses.