Characterization and detection of a novel idaeovirus infecting blackcurrant

A novel virus was discovered in a blackcurrant accession (Ribes nigrum L.) at the USDA genebank in Oregon, USA. The genome consists of two positive-sense, single-stranded RNAs with the first encoding a 197 kDa multifunctional protein with methyl transferase, helicase and RNA-dependent RNA polymerase enzymatic motifs. The second molecule encodes two putative proteins; the 39 kDa movement and 30 kDa coat proteins. Both RNAs have conserved sequences and structures at the 5′ and 3′ termini. The genome organization, sequence and phylogenetic analyses indicate that the virus is a putative new member of the genus Idaeovirus, as it consistently groups with privet leaf blotch-associated virus and raspberry bushy dwarf virus. A duplex RT-PCR assay was developed for rapid detection of both genomic RNAs simultaneously. The work presented in this communication will assure the health status of blackcurrant plants in mother blocks, nurseries and production fields alike.