Sclertoinia sclerotiorum is a destructive soil-borne plant pathogenic fungus, which has a broad host range of over 450 species and subspecies among 64 genera of plants (Boland, 1994).More than 10 mycoviruses have previously been identified from S.sclerotiorum and most of reported mycoviruses caused hypovirulence.These mycoviruses are important biological resources for discussion the evolution, ecology of viruses, and biocontrol strategies.In the present study, a hypovirulent strain YX26 was originally isolated from a sclerotium collected from a diseased rapeseed plant in Jiangxi province.Compared to strains Ep-1PNA367 and 1980 of S.sclerotiroum, strain YX26 showed hypovirulence including abnormal colony morphology, slower growth rate, lower virulence on detached rapeseed plant leaves and no sclerotia production.DsRNA extraction suggested that 11 dsRNA segments at least exist in strain YX26.The full eDNA sequences of one dsRNA segments were determined by conventional random priming cDNA synthesis,RT-PCR and RACE clones.Sequence analysis showed that the obtained sequence is the genome of Sclerotinia sclerotiorum victorivirus 1 (SsVV1/YX26).The full cDNA sequence of SsVV1/YX26 was comprised of 5142 nts with G + C content of 50.1%.It contains a 5-untranslated region (UTR) of 284 nts and a 3-UTR of 89 nts.SsVV1/YX26 comprises two large overlapping ORFs which were predicted to encode RdRp and coat protein (CP).The RdRp contains a typical conserved domain of RT-like superfamily, and CP contains a conserved Multi-domain.Both CP and RdRp of SsVV1/YX26 share high sequence identity with that of Aspergillus foetidus slow virus 1 (AfV-S1).The start codon of RdRp of SsVV1 overlaps stop codon for upstread CP in the tetranucleotide sequence AUGA, which was a common characteristic in the members of Victorivirus.Phylogenetic analysis showed that SsVV1 is a novel dsRNA virus belonging to Victorivirus of the family Totiviridae.The relationship between SsVV1/YX26 and hypovirulent traits of strain YX26 needs to be further investigated.