Complete nucleotide sequence of an alphaendornavirus isolated from common buckwheat (Fagopyrum esculentum)

A double-stranded RNA (dsRNA) of approximately 16 kbp was isolated from symptomless common buckwheat (Fagopyrum esculentum) plants. The size of the dsRNA suggested that it was the replicative form of an endornavirus. The dsRNA was sequenced, and it consisted of 15,677 nt, containing a single open reading frame that potentially encoded a polyprotein of 5190 aa. The polyprotein contained conserved domains for a viral methyltransferase, viral RNA helicase 1, MSCRAMM family adhesion SdrC, UDP-glycosyltransferase, and viral RNA-dependent RNA polymerase 2. A site-specific nick in the plus strand was detected near the 5' end of the dsRNA. BLASTp analysis showed that the polyprotein shared the highest identity with the polyprotein of winged bean endornavirus 1. Results of phylogenetic analysis supported placing this novel virus from common buckwheat, which was provisionally named "Fagopyrum esculentum endornavirus 1", in the genus Alphaendornavirus of the family Endornaviridae.