Complete sequence of a double-stranded RNA from the phytopathogenic fungus Erysiphe cichoracearum that might represent a novel endornavirus

A double-stranded RNA (dsRNA) HBJZ1506 recovered from the phytopathogenic fungus Erysiphe cichoracearum infecting Calendula officinalis in Jingzhou, Hubei Province, China, was sequenced. HBJZ1506 comprises 11,908 nucleotides (nt) and contains a 11,859-nt-long open reading frame (ORF) coding for a polypeptide that is 61 % identical to that of a putative endornavirus named grapevine endophyte endornavirus (GeEV). The putative polyprotein has an RNA-dependent RNA polymerase (RdRp) domain and an RNA helicase domain, which show homology to and have an arrangement that is similar to that of their counterparts in approved or putative endornaviruses. In a phylogenetic tree constructed using amino acid sequences of the RdRp region of HBJZ1506 and selected endornaviruses, HBJZ1506 clustered with endornaviruses and formed a well-supported monophyletic branch with GeEV. These results suggest that HBJZ1506 might represent a novel endornavirus, for which the name Erysiphe cichoracearum endornavirus (EcEV) is proposed.