A novel endornavirus isolated from cluster bean (Cyamopsis tetragonoloba)

Cluster bean (Cyamopsis tetragonoloba), also called guar, is a drought-tolerant annual legume. We conducted investigations to characterize a large dsRNA (~13-14 kbp) detected in a symptomless cluster bean genotype. The dsRNA was gel-purified and used for Illumina MiSeq sequencing. Reads were assembled, and BLASTx search results showed sequence similarity with viruses classified within the family Endornaviridae. The complete sequence of the putative endornavirus consisted of 12,895 nt and contained an open reading frame which coded for a polyprotein of 4,207 aa with conserved domains for methyltransferase, helicase, and RNA-dependent RNA polymerase. The virus was named cluster bean endornavirus 1 (CBEV-1). A BLASTx search using the polyprotein sequence showed that the closest endornavirus to CBEV-1 was Hordeum vulgare endornavirus.