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A novel positive-stranded RNA virus provisionally named "citrus virus C" (CVC) was discovered in citrus trees displaying mottling symptoms. Its genome comprises 7,215 nucleotides (nt), excluding the 3’ poly(A) tail, and contains two open reading frames (ORFs) that encode a replication-associated polyprotein (RP) and a putative coat protein (CP). The CVC genome contains a 16-nt ‘marafibox’, which is highly conserved in most viruses belonging to the genus Marafivirus of the same family. Sequence analysis suggested that the virus is most closely related to grapevine Red Globe virus (GRGV), which is yet to be officially classified in the family Tymoviridae. The sequence identities between CVC and GRGV in the whole genome (50.7%, nt) and CP (49.4% for amino acid, and 53.9% for nt) are lower than the thresholds (80% in the genome and 90% in the CP) for species demarcation in the family. Therefore, it is legitimate to propose that CVC is a member of new species in the family Tymoviridae.

A new virus with sequence similarities to members of the genus Cavemovirus in the family Caulimoviridae was identified in an Epiphyllum hybrid. The complete genome of the virus, tentatively named "epiphyllum virus 4" (EpV-4), was determined to be 7,296 nucleotides long. Its circular genome organization is typical of cavemoviruses, containing four open reading frames. This virus and the two known cavemoviruses share 67-69% and 72-75% overall nucleotide sequence identity in the replicase gene. Phylogenetic analysis placed EpV-4 in a same cluster with the two recognized cavemoviruses. Thus, EpV-4 should be considered a representative of a third species of the genus Cavemovirus. The virus was transmitted by grafting.

One large contig with high sequence similarity to Asian prunus virus 2 was identified by high-throughput sequencing from a camellia (Camellia japonica) tree with ringspot symptoms. The complete genome of this new virus was determined to be 8829 nucleotides long, excluding the 3' poly(A) tail. Its genome organization resembles that of known foveaviruses but contains an additional open reading frame in the 3'-terminal region. Phylogenetic analysis also places this virus with members of the genus Foveavirus in the family Betaflexiviridae in the same subgroup. The virus, which is provisionally named "camellia ringspot-associated virus 4″, shares 50-56% nucleotide sequence identity with other foveaviruses and should represent a new species in the genus.

A novel positive-stranded RNA virus provisionally named "citrus virus C" (CVC) was discovered in citrus trees displaying mottling symptoms. Its genome comprises 7,215 nucleotides (nt), excluding the 3' poly(A) tail, and contains two open reading frames (ORFs) that encode a replication-associated polyprotein (RP) and a putative coat protein (CP). The CVC genome contains a 16-nt 'marafibox', which is highly conserved in most viruses belonging to the genus Marafivirus of the same family. Sequence analysis suggested that the virus is most closely related to grapevine Red Globe virus (GRGV), which is yet to be officially classified in the family Tymoviridae. The sequence identities between CVC and GRGV in the whole genome (50.7%, nt) and CP (49.4% for amino acid, and 53.9% for nt) are lower than the thresholds (80% in the genome and 90% in the CP) for species demarcation in the family. Therefore, it is legitimate to propose that CVC is a member of new species in the family Tymoviridae.

In 2009, a new viral disease of citrus caused by citrus yellow vein clearing virus (CYVCV) was first discovered in China. CYVCV is considered to be the most serious pathogen affecting lemon production. In this study, a sensitive and reliable reverse transcription droplet digital polymerase chain reaction (RT-ddPCR) assay was developed to detect and quantify CYVCV without references. The specificity of the assay was demonstrated by its failure to amplify other relevant citrus viruses. The quantitative linearity, sensitivity and accuracy of RT-ddPCR for detecting CYVCV were compared to those of real-time RT-PCR. The results showed that both methods had a high degree of linearity (R2 = 0.9776) and quantitative correlation. Furthermore, RT-ddPCR was found to be 100 times more sensitive than real-time RT-PCR, and it can therefore be used to detect CYVCV in individual arthropods. In summary, the results demonstrated that the RT-ddPCR assay is a promising approach for quantitative detection of CYVCV with high precision and accuracy.

A large contig with sequence similarities to several nucleorhabdoviruses was identified by high-throughput sequencing analysis from a black currant (Ribes nigrum L.) cultivar. The complete genome sequence of this new nucleorhabdovirus is 14,432 nucleotides long. Its genomic organization is very similar to those of unsegmented plant rhabdoviruses, containing six open reading frames in the order 3'-N-P-P3-M-G-L-5. The virus, which is provisionally named "black currant-associated rhabdovirus", is 41-52% identical in its genome nucleotide sequence to other nucleorhabdoviruses and may represent a new species in the genus Nucleorhabdovirus.

The complete genomic sequence of a novel potyvirus was determined from Paris polyphylla var. yunnanensis. Its genomic RNA consists of 9,660 nucleotides (nt) excluding the 3'-terminal poly (A) tail, containing the typical open reading frame (ORF) of potyviruses and encoding a putative large polyprotein of 3030 amino acids. The virus shares 53.9-70.1% nt sequence identity and 43.9-73.2% amino acid sequence identity with other viruses classified within the genus Potyvirus. Proteolytic cleavage sites and conserved motifs of the potyviruses were identified in the polyprotein and within individual proteins. Phylogenetic analysis indicated that the virus is most closely related to members of the BCMV subgroup. The results suggest that the virus should be classified as a novel species within the genus Potyvirus, which we tentatively name "Paris mosaic necrosis virus".

A new single-stranded positive-sense RNA virus, which shares the highest nucleotide (nt) sequence identity of 53.4% with the genome sequence of cherry-associated luteovirus South Korean isolate (ChALV-SK, genus Luteovirus), was discovered in this work. It is provisionally named apple-associated luteovirus (AaLV). The complete genome sequence of AaLV comprises 5,890 nt and contains eight open reading frames (ORFs), in a very similar arrangement that is typical of members of the genus Luteovirus. When compared with other members of the family Luteoviridae, ORF1 of AaLV was found to encompass another ORF, ORF1a, which encodes a putative 32.9-kDa protein. The ORF1-ORF2 region (RNA-dependent RNA polymerase, RdRP) showed the greatest amino acid (aa) sequence identity (59.7%) to that of cherry-associated luteovirus Czech Republic isolate (ChALV-CZ, genus Luteovirus). The results of genome sequence comparisons and phylogenetic analysis, suggest that AaLV should be a member of a novel species in the genus Luteovirus. To our knowledge, it is the sixth member of the genus Luteovirus reported to naturally infect rosaceous plants.

A new badnavirus was identified in an ornamental camellia tree with yellow mottle symptom. The complete circular double-stranded DNA genome of this virus was found to consist of 8,203 bp. Its genome organization is typical of badnaviruses, containing three open reading frames (ORFs). ORFs 1 and 2 encode putative proteins with unknown functions. ORF3 encodes a large polyprotein that contains almost all of the conserved domains of badnaviruses. The virus shares 55-62% nucleotide sequence identities with other badnaviruses in the RT+RNase H region. Phylogenetic analyses placed it in group I of the genus Badnavirus. Therefore, this virus, which is tentatively named "camellia Lemon Glow virus", should represent a new species of the genus Badnavirus. This virus was found to be present in approximately a quarter of camellia trees tested.

A new virus with a circular double-stranded DNA genome was discovered in green Sichuan pepper with vein clearing symptoms. Its complete genome of 8,014 bp contains three open reading frames (ORF) on the plus strand, which is typical of members of the genus Badnavirus in the family Caulimoviridae. Sequence comparisons revealed that the new virus has the highest nucleotide sequence identity with grapevine vein-clearing virus (GVCV). In particular, the identity of the two viruses in the ORF3 RT-RNase H region is 71.9%, which is below the species demarcation cutoff of 80% for badnaviruses. Phylogenetic analysis also placed the new virus with GVCV in a cluster. The virus was tentatively named “green Sichuan pepper vein clearing-associated virus” (GSPVCaV). The geographical distribution and genetic diversity of GSPVCaV were studied. Another isolate was found to be highly divergent.

Contigs with sequence homologies to cherry-associated luteovirus were identified by high-throughput sequencing analysis in two peach accessions. Complete genomic sequences of the two isolates of this virus were determined to be 5,819 and 5,814 nucleotides long, respectively. The genome of the new virus is typical of luteoviruses, containing eight open reading frames in a very similar arrangement. Its genomic sequence is 58-74% identical to those of other members of the genus Luteovirus. These sequences thus belong to a new virus, which we have named "peach-associated luteovirus".

Unfortunately, the Acknowledgement, ethical statement and the Conflict of interest statements were not included in the online publication and updated here in this Erratum.

A novel positive-strand RNA virus infecting citrus with the tentative name "citrus leaf blotch virus 2" (CLBV-2), was identified in the present work. The complete genome sequence of CLBV-2 comprises 8,697 nucleotides (nt) excluding a poly(A) tail and three open reading frames (ORFs), showing the highest nucleotide sequence identity with the Actinidia strain (JN983456) of citrus leaf blotch virus (CLBV). The putative movement protein (ORF2), coat protein (ORF3), and 3' untranslated region (UTR) shared high sequence similarity with those of the extant CLBV isolates. In contrast, only low sequence similarity was observed in the 5' UTR and putative replicase polyprotein (ORF1) regions. The distant phylogenetic relationship between CLBV-2 and CLBV was deduced based on whole-genome nucleotide and whole-ORF1 amino acid sequence comparisons. Sequence comparisons suggest that CLBV-2 acquired an ORF2-ORF3-3' UTR region homologous to CLBV by recombination with of an unknown citrivirus. In view of the fact that this genomic recombination event appears to have occurred between members of different species in the genus Citrivirus, we propose that CLBV-2 should be considered a member of a distinct species.

The complete genome sequence of a novel member of the genus Macluravirus was determined from yam plants with chlorotic and necrotic symptoms in China. The genomic RNA consists of 8,261 nucleotides (nt) excluding the 3’-terminal poly(A) tail, containing one long open reading frame (ORF) encoding a large putative polyprotein of 2,627 amino acids. Its genomic structure is typical of macluraviruses, which lack the P1 protein, N-terminal HC-Pro, and D-A-G motif for aphid transmission that are found in potyviruses. The virus shares 56.3-63.8% sequence identity at the genome sequence level and 49.7-63.9% at the polyprotein sequence level with other members of the genus Macluravirus. Phylogenetic analysis based on the complete polyprotein sequence of representative members of the family Potyviridae clearly places the virus within the genus Macluravirus. These results suggest that the virus, tentatively named “yam chlorotic necrosis virus” (YCNV), should be considered a member of a novel species in the genus Macluravirus.

Complete genomic sequences of nine isolates of sweet potato symptomless virus 1 (SPSMV-1), a virus of the genus Mastrevirus in the family Geminiviridae, were determined from sweet potato accessions from different countries and found to be 2,559-2,602 nucleotides in length. These isolates shared 97-100% genome sequence identity and had an unusual nonanucleotide sequence (TAAGATTCC) in a large intergenic region as well as an additional open reading frame, C3, which is conserved in dicot-infecting mastreviruses.

The complete genome of sweet potato latent virus (SPLV) was determined to be 10081 nucleotides long excluding the 3' poly (A) tail. The genome contains a single large open reading frame encoding a polyprotein of 3247 amino acids. Its genomic organization is typical of potyviruses and contains motifs conserved in members of the genus Potyvirus. Pairwise comparisons show that SPLV shares identities of 50.0 %-56.3 % to other potyviruses at the genomic sequence level. Phylogenetic analysis shows that SPLV is closely related to four other sweet potato potyviruses in the sweet potato feathery mottle virus lineage, but it lacks the unique PISPO in the P1 region of those viruses. The genome analyses confirm that SPLV is a distinct sweet potato virus in the genus Potyvirus.

The complete genomic sequence of Celery mosaic virus (CeMV) was found to be 9999 nucleotides in length, excluding the 3' poly(A) tail. The genome contains a single large open reading frame encoding a polyprotein of 3181 amino acids. Its genomic organization is typical of potyviruses and contains conserved motifs found in members of the genus Potyvirus. Pairwise comparison of the polyprotein sequences shows that CeMV shares 39.0-71.9% sequence identity with other members of the genus Potyvirus. Phylogenetic analysis based on the polyprotein sequences indicates that CeMV is most closely related to Apium virus Y, and together with Panax virus Y, the three viruses form a distinct clade.

The host range and complete nucleotide sequences of two Cherry necrotic rusty mottle virus (CNRMV) isolates (FC4 and FC5) infecting flowering cherry accessions imported from Japan are described. Of the plants tested, cherry, peach, apricot and almond became infected, but only sweet cherry cv. 'Canindex', Nanking cherry and apricot cv. 'Tilton' showed a mild foliar mottle. The genomic sequences of CNRMV-FC4 and CNRMV-FC5 are 8,430 and 8,429 nt in length, excluding the 3' poly (A) tail. They contain seven open reading frames encoding for a putative virus replicase, "triple gene block" proteins, a coat protein and two proteins with unknown functions. The two CNRMV-FC isolates share 96% identity in the genomic sequences, and their genome organizations are virtually identical to that of a German CNRMV isolate (CNRMV-GER). However, they differ from CNRMV-GER by 14% in the overall nucleotide sequence and 2% (ORF2) to 30% (ORF5a) in the derived amino acid sequences of individual gene products.

A novel strain of Japanese yam mosaic virus (JYMV-CN) was identified in a yam plant with foliar mottle symptoms in China. The complete genomic sequence of JYMV-CN was determined. Its genomic sequence of 9701 nucleotides encodes a polyprotein of 3247 amino acids. Its organization is virtually identical to that of two JYMV isolates from Japan. With the latter, it shares nucleotide sequence identities of only 74.7–74.8 %, indicating it might be a member of a new species. However, sequence analysis of the polyprotein and individual proteins suggested that the Chinese isolate is a divergent JYMV strain in the process of speciation.

The complete genomic sequences of two isolates of pokeweed mosaic virus (PkMV) were determined to be 9512 nucleotides long, excluding the poly(A) tail. Their genomic organization is typical of potyviruses and contains conserved motifs found in members of the genus Potyvirus. Pairwise comparisons showed that PkMV and other members of the genus Potyvirus share 51.0-57.5 % sequence identity at the genome sequence level and 39.8-53.0 % at the polyprotein sequence level. Phylogenetic analysis indicated that PkMV is most closely related to several viruses in the PVY group of the genus Potyvirus. The genomic information obtained for PkMV suggests that this virus is a distinct potyvirus.

The complete nucleotide sequence of tomato infectious chlorosis virus (TICV) was determined and compared with those of other members of the genus Crinivirus. RNA 1 is 8,271 nucleotides long with three open reading frames and encodes proteins involved in replication. RNA 2 is 7,913 nucleotides long and encodes eight proteins common within the genus Crinivirus that are involved in genome protection, movement and other functions yet to be identified. Similarity between TICV and other criniviruses varies throughout the genome but TICV is related more closely to lettuce infectious yellows virus than to any other crinivirus, thus identifying a third group within the genus.