Genomic organization of a novel partitivirus from the phytopathogenic fungus Ustilaginoidea virens

From the plant pathogen Ustilaginoidea virens, four double-stranded RNA (dsRNA) segments designated Uv-dsRNA1, -2, -3, and -4 were isolated, cloned, and sequenced. Uv-dsRNA1 (1775 bp) and -2 (1588 bp) potentially encode an RNA-dependent RNA polymerase (RdRp) and a viral coat protein (CP), respectively. Since the RdRp and CP sequences encoded by Uv-dsRNA1 and -2, respectively, are most closely related to, but clearly distinct from, those of viruses of the genus Partitivirus, they appear to be the two genome segments of a new partitivirus, for which the name Ustilaginoidea virens partitivirus 1 is proposed. In contrast, Uv-dsRNA3 (1352 bp) did not share significant sequence similarity with GenBank sequences, and the ORF of Uv-dsRNA4 (1119 bp) was only 32 % identical to a functionally unknown protein (GaRVMS2s3gp1) encoded by Gremmeniella abietina RNA virus MS2.