Research Of Mycoviruses In Magnaporthe Oryzae

Rice blast is one of the most devastating diseases around the world,and reducing the production of rice anunal.The main approaches for rice blast control are resistant breeding and chemical fungicides application.Mycoviruses are viruses that infect fungi,and are widely presence in fungi.Some of mycoviruses could be used as resources to biological control for fungal diseases.In this reserach,strain YC13,a Magnaporthe oryzae strain isolated from a naturally diseased rice leaf,was studied.Seven dsRNA fragments(F1 to F7)were detected in strain YC13.Amino acid sequence of fragment F1 shared 99% identity with coat protein(CP)and RNA-dependent RNA polymerase(RdRp)of Magnaporthe oryzae virus 2(MoV2).Fragments F4 and F5 showed 97% and 99% similarity with RdRp and CP of Magnaporthe oryzae partitivirus virus 1(MoPV1),respectively.Thus the fragments of F4 and F5 were the genome of MoPV1.MoPV1 genome was composed of two dsRNA fragments(dsRNA1 and dsRNA2).dsRNA1 encodes RdRp,while dsRNA2 encodes CP.Phylogenetic analysis of the conserved RdRp region showed that MoPV1 is a member of Gammapartitivirus.In order to understand the influence of MoPV1 on its host,PEG-mediedted protoplasts transfection was conducted with viral particles derived from strain YC13.RB11T25 was infected with MoPV1 alone.Compared to strain RB11(virus-free strain),strain RB11T25 showed lower conidial production and less virulence on barley.These results suggested that MoPV1 may develop to a potential virocontrol agent to combate blast disease.We isolated 171 strains of M.oryzae from the rice leaf collected from the field in 2015.The mycoviruses have been analyzed by metatranscriptomics.Sixty-six virus-like contigs were identified.Twenty-two viruses were verified by Reverse transcription polymerase chain reaction,including twelve +ssRNA viruses,three-ssRNA viruses and seven dsRNA viruses.Phylogenetic trees were constructed with conserved RdRp domain.These viruses are assigned in Ourmiavirus,Chrysoviridae,Partitiviridae,Totiviridae,Mononegavirales and unclassified viruses.In addition,6659 sequences which no annotation information were obtained.The results enriched the knowledge of virus in M.oryzae.