Molecular Characterization of a Novel Mycovirus Isolated from Binucleate Rhizoctonia AG‑Bb strain 8-Q-36.

Mycoviruses are widespread in fungi, their diversity across different taxonomic ranks remains insufficiently documented. In this study, a novel mycovirus from the strain 8-Q-36 of binucleate Rhizoctonia AG-Bb, were identified using High- throughput sequencing technology and it was tentatively named as Orthocurvulavirus rhizoctonia 1. The viral genome consists of two dsRNA components, 2252 and 1720 nt in length. DsRNA1 contains a open reading frame (ORF) encoding a 80.3-kDa RdRp and dsRNA2 contains a ORF encoding a 54.3-kDa hypothetical protein. The encoded RdRp exhibited the highest sequence similarity to Rhizoctonia fumigata bipartite virus 1 (YP_009134757.1, 80.31%), with a sequence coverage of 100%. Phylogenetic analysis based on RdRp amino acid sequences indicated that OCR1 clusters within an unclassified group of dsRNA viruses phylogenetically affiliated with the genus Orthocurvulavirus. These results suggest that OCR1 may represent a novel species within this genus, pending formal taxonomic proposal and official ratification.