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 dwa... More
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.
The USDA National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon, is a genebank preserving genetic diversity of several fruit and nut crop species from around the globe (Postman et al. 2006). A survey was initiated to study the virus status of the berry crops at NCGR and determine whether unusual symptoms might be associated with the presence of viruses. One of the NCGR berry crops, blackcurrant (Ribes nigrum L.), is popular because of its piquant berries and positive health effects (Terry 2014). Blackcurrants are primarily grown in northern latitudes and especially in Europe where 99% of the world production is concentrated (Mitchell et al. 2011). NCGR maintains about 50 unique clonal Ribes nigrum accessions as living plants (USDA-NPGS 2016).
There are several viruses affecting the crop (Converse 1987; James and Phelan 2016; Petrzik et al. 2016a, 2016b), with blackcurrant reversion virus, the causal agent of reversion disease, considered to be the most economically important (Susi 2004). As part of our study we identified five new virus species in material exhibiting virus-like symptoms (Fig. 1; Ho and Tzanetakis 2014; Ho et al. 2015b) with this communication focusing on a potentially new member of the genus Idaeovirus, tentatively named as blackcurrant idaeovirus (BCIV).
