The nucleotide sequence and genome organization of two victoriviruses from the rice false smut fungus Ustilaginoidea virens

Ustilaginoidea virens is the causal agent of false smut disease of rice. The dsRNA-Ls from a U. virens strain of Uv0901 containing three dsRNA bands were separated and sequenced. The dsRNA-Ls, with molecular weight of 5 kbp, were demonstrated to be two dsRNA segments referenced as dsRNA-L1 and dsRNA-L2. The two dsRNAs each contained two overlapped open reading frames, and showed significant similarity to those of capsid protein and RNA-directed RNA polymerase, respectively, of members of the family Totiviridae. Homology research and phylogenic analysis indicated that the dsRNA-L1 was a conspecific species of the previous reported Ustilaginoidea virens RNA virus 1, named Ustilaginoidea virens RNA virus Uv0901, and the dsRNA-L2 was a new number of the Victorivirus in the family Totiviridae, designed as Ustilaginoidea virens RNA virus 3.