Complete genome sequence of a novel partitivirus identified in Rhizoctonia solani AG-4 HG III isolate Rs31.

The soilborne phytopathogen Rhizoctonia solani (R. solani) infects multiple hosts and is capable of causing severe diseases in many economically important crops, including rice, potato, and wheat. This report describes the discovery and molecular characterization of a previously unrecognized mycovirus, tentatively named "Rhizoctonia solani partitivirus Rs31" (RsPV-Rs31), isolated from R. solani AG-4 HG III strain Rs31. Genome sequencing and analysis revealed that RsPV-Rs31 consists of two double-stranded RNA (dsRNA) segments with a length of 1991 bp (dsRNA1) and 1728 bp (dsRNA2), respectively. The larger segment, dsRNA1, contains a single open reading frame (ORF1) predicted to produce a 622-amino-acid RNA-dependent RNA polymerase (RdRp) with conserved functional motifs. The smaller dsRNA2 segment containing ORF2 was predicted to encode a 558-amino-acid capsid protein (CP). BLASTp analysis of the predicted RdRp revealed significant sequence similarity to viruses belonging to the genus Alphapartitivirus and other unclassified partitiviruses listed in the ICTV database. Phylogenetic analysis based on RdRp protein sequences suggested that RsPV-Rs31 is a novel member of the family Partitiviridae.