Complete Genome Sequence of the First Chrysovirus From the Phytopathogenic Fungus Alternaria Solani on Potato in China

Abstract The full genome of a double-stranded RNA (dsRNA) mycovirus, which was isolated from Alternaria solani strain DT-10 causing potato foliar disease and designated as Alternaria solani chrysovirus 1 (AsCV1), consisted of four dsRNA segments (dsRNA 1–4) with the length of 3600 bp, 3128 bp, 2996 bp, and 2714 bp, respectively. RNA-dependent RNA polymerase (RdRp, 1084 amino acids (aa)), putative capsid protein (905 aa), Alphachryso-P3 (835 aa), and Alphachryso-P4 (729 aa) were encoded by dsRNA1, dsRNA2, dsRNA3, and dsRNA4, respectively, which had the highest identities of 41.77%-72.38% to the counterparts of Helminthosporium victoriae virus 145S (HvV145S) in the genus Alphachrysovirus of the family Chrysoviridae. Moreover, the 5′-untranslated regions (UTRs) with several unique inserts (3–37 bp) and deletions (5–64 bp) of AsCV1 dsRNA 1–4 shared 51.65%-68.01% identities to those of HvV145S. Phylogenetic analysis of RdRp suggested that AsCV1 clustered the most closely with HvV145S. Based on the characteristics of distinct host, low identities of encoded proteins, special traits in 5′-UTRs of dsRNA 1–4, and phylogenetic analysis of RdRp, AsCV1 was confirmed to be a new species in the genus Alphachrysovirus. To our best knowledge, this is the first alphachrysovirus identified from phytopathogenic A. solani.