Search Results (7)

Agricultural pests can cause direct damage to crops, including chlorosis, loss of vigor, defoliation, and wilting. In addition, they can also indirectly damage plants, such as by transmitting pathogenic micro-organisms while feeding on plant tissues, affecting the productivity and quality of crops and interfering with agricultural production. Among the known arthropod pests, mites are highly prevalent in global agriculture, particularly those from the Tetranychidae family. The two-spotted spider mite, Tetranychus urticae, is especially notorious, infesting about 1600 plant species and causing significant agricultural losses. Despite its impact on agriculture, the virome of T. urticae is poorly characterized in the literature. This lack of knowledge is concerning, as these mites could potentially transmit plant-infecting viral pathogens, compromising food security and complicating integrated pest management efforts. Our study aimed to characterize the virome of the mite T. urticae by taking advantage of publicly available RNA deep sequencing libraries. A total of 30 libraries were selected, covering a wide range of geographic and sampling conditions. The library selection step included selecting 1 control library from each project in the NCBI SRA database (16 in total), in addition to the 14 unique libraries from a project containing field-collected mites. The analysis was conducted using an integrated de novo virus discovery bioinformatics pipeline developed by our group. This approach revealed 20 viral sequences, including 11 related to new viruses. Through phylogenetic analysis, eight of these were classified into the Nodaviridae, Kitaviridae, Phenuiviridae, Rhabdoviridae, Birnaviridae, and Qinviridae viral families, while three were characterized only at the order level within Picornavirales and Reovirales. The remaining nine viral sequences showed high similarity at the nucleotide level with known viral species, likely representing new strains of previously characterized viruses. Notably, these include the known Bean common mosaic virus (BCMV) and Phaseolus vulgaris alphaendornavirus 1, both of which have significant impacts on bean agriculture. Altogether, our results expand the virome associated with the ubiquitous mite pest T. urticae and highlight its potential role as a transmitter of important plant pathogens. Our data emphasize the importance of continuous virus surveillance for help in the preparedness of future emerging threats. Full article

The cucurbit vegetable chieh-qua (Benincasa hispida var. chieh-qua How) is an important crop in South China and southeast Asian countries. Viral diseases cause substantial loss of chieh-qua yield. To identify the viruses that affect chieh-qua in China, ribosomal RNA-depleted total RNA sequencing was performed using chieh-qua leaf samples with typical viral symptoms. The virome of chieh-qua comprises four known viruses (melon yellow spot virus (MYSV), cucurbit chlorotic yellows virus (CCYV), papaya ringspot virus (PRSV) and watermelon silver mottle virus (WSMoV) and two novel viruses: cucurbit chlorotic virus (CuCV) in the genus Crinivirus and chieh-qua endornavirus (CqEV) in the genus Alphaendornavirus. The complete genomes of the two novel viruses in chieh-qua and three other isolates of CuCV in pumpkin, watermelon and cucumber were determined and the recombination signals of pumpkin and watermelon isolates of CuCV were detected. A reverse transcriptase PCR indicated that the dominant viruses of chieh-qua in Hainan are MYSV (66.67%) and CCYV (55.56%), followed by CuCV (27.41%), WSMoV (7.41%), cucumber mosaic virus (8.15%), zucchini yellow mosaic virus (6.67%), PRSV (6.67%) and CqEV (35.56%). Our findings support diagnostic and prevalence studies of viruses infecting chieh-qua in China, enabling sustainable control strategies for cucurbit viruses worldwide. Full article

Endornaviruses are capsidless linear (+) ssRNA viruses in the family Endornaviridae. In this study, Scelrotinia sclerotiorum endornavirus 11 (SsEV11), a novel endornavirus infecting hypovirulent Sclerotinia sclerotiorum strain XY79, was identified and cloned using virome sequencing analysis and rapid amplification of cDNA ends (RACE) techniques. The full-length genome of SsEV11 is 11906 nt in length with a large ORF, which encodes a large polyprotein of 3928 amino acid residues, containing a viral methyltransferase domain, a cysteine-rich region, a putative DEADc, a viral helicase domain, and an RNA-dependent RNA polymerase (RdRp) 2 domain. The 5’ and 3’ untranslated regions (UTR) are 31 nt and 90 nt, respectively. According to the BLAST result of the nucleotide sequence, SsEV11 shows the highest identity (45%) with Sclerotinia minor endornavirus 1 (SmEV1). Phylogenetic analysis based on amino acid sequence of RdRp demonstrated that SsEV11 clusters to endornavirus and has a close relationship with Betaendornavirus. Phylogenetic analysis based on the sequence of endornaviral RdRp domain indicated that there were three large clusters in the phylogenetic tree. Combining the results of alignment analysis, Cluster I at least has five subclusters including typical members of Alphaendornavirus and many unclassified endornaviruses that isolated from fungi, oomycetes, algae, and insects; Cluster II also has five subclusters including typical members of Betaendornavirus, SsEV11, and other unclassified viruses that infected fungi; Cluster III includes many endorna-like viruses that infect nematodes, mites, and insects. Viruses in Cluster I and Cluster II are close to each other and relatively distant to those in Cluster III. Our study characterized a novel betaendornavirus, SsEV11, infected fungal pathogen S. sclerotiorum, and suggested that notable phylogenetic diverse exists in endornaviruses. In addition, at least, one novel genus, Gammaendornavirus, should be established to accommodate those endorna-like viruses in Cluster III. Full article

The Australasian biogeographic realm is a major centre of diversity for orchids, with every subfamily of the Orchidaceae represented and high levels of endemism at the species rank. It is hypothesised that there is a commensurate diversity of viruses infecting this group of plants. In this study, we have utilised high-throughput sequencing to survey for viruses infecting greenhood orchids (Pterostylidinae) in New South Wales and the Australian Capital Territory. The main aim of this study was to characterise Pterostylis blotch virus (PtBV), a previously reported but uncharacterised virus that had been tentatively classified in the genus Orthotospovirus. This classification was confirmed by genome sequencing, and phylogenetic analyses suggested that PtBV is representative of a new species that is possibly indigenous to Australia as it does not belong to either the American or Eurasian clades of orthotospoviruses. Apart from PtBV, putative new viruses in the genera Alphaendornavirus, Amalgavirus, Polerovirus and Totivirus were discovered, and complete genome sequences were obtained for each virus. It is concluded that the polerovirus is likely an example of an introduced virus infecting a native plant species in its natural habitat, as this virus is probably vectored by an aphid, and Australia has a depauperate native aphid fauna that does not include any species that are host-adapted to orchids. Full article

Viruses are an important disease source for beans. In order to evaluate the impact of virus disease on Phaseolus biodiversity, we determined the identity and distribution of viruses infecting wild and domesticated Phaseolus spp. in the Mesoamerican Center of Domestication (MCD) and the western state of Nayarit, Mexico. We used small RNA sequencing and assembly to identify complete or near-complete sequences of forty-seven genomes belonging to nine viral species of five genera, as well as partial sequences of two putative new endornaviruses and five badnavirus- and pararetrovirus-like sequences. The prevalence of viruses in domesticated beans was significantly higher than in wild beans (97% vs. 19%; p < 0.001), and all samples from domesticated beans were positive for at least one virus species. In contrast, no viruses were detected in 80–83% of the samples from wild beans. The Bean common mosaic virus and Bean common mosaic necrosis virus were the most prevalent viruses in wild and domesticated beans. Nevertheless, Cowpea mild mottle virus, transmitted by the whitefly Bemisia tabaci, has the potential to emerge as an important pathogen because it is both seed-borne and a non-persistently transmitted virus. Our results provide insights into the distribution of viruses in cultivated and wild Phaseolus spp. and will be useful for the identification of emerging viruses and the development of strategies for bean viral disease management in a center of diversity. Full article

Neofusicoccum parvum is a fungal plant-pathogen belonging to the family Botryosphaeriaceae, and is considered one of the most aggressive causal agents of the grapevine trunk disease (GTD) Botryosphaeria dieback. In this study, the mycovirome of a single strain of N. parvum (COLB) was characterized by high throughput sequencing analysis of total RNA and subsequent bioinformatic analyses. Contig annotations, genome completions, and phylogenetic analyses allowed us to describe six novel mycoviruses belonging to four different viral families. The virome is composed of two victoriviruses in the family Totiviridae, one alphaendornavirus in the family Endornaviridae, two mitoviruses in the family Mitoviridae, and one narnavirus belonging to the family Narnaviridae. The presence of the co-infecting viruses was confirmed by sequencing the RT-PCR products generated from total nucleic acids extracted from COLB. This study shows that the mycovirome of a single N. parvum strain is highly diverse and distinct from that previously described in N. parvum strains isolated from grapevines. Full article

Using double-strand RNA (dsRNA) high-throughput sequencing, we identified five RNA viruses in a bean golden mosaic virus (BGMV)-resistant common bean transgenic line with symptoms of viral infection. Four of the identified viruses had already been described as infecting common bean (cowpea mild mottle virus, bean rugose mosaic virus, Phaseolus vulgaris alphaendornavirus 1, and Phaseolus vulgaris alphaendornavirus 2) and one is a putative new plant rhabdovirus (genus Cytorhabdovirus), tentatively named bean-associated cytorhabdovirus (BaCV). The BaCV genome presented all five open reading frames (ORFs) found in most rhabdoviruses: nucleoprotein (N) (ORF1) (451 amino acids, aa), phosphoprotein (P) (ORF2) (445 aa), matrix (M) (ORF4) (287 aa), glycoprotein (G) (ORF5) (520 aa), and an RNA-dependent RNA polymerase (L) (ORF6) (114 aa), as well as a putative movement protein (P3) (ORF3) (189 aa) and the hypothetical small protein P4. The predicted BaCV proteins were compared to homologous proteins from the closest cytorhabdoviruses, and a low level of sequence identity (15–39%) was observed. The phylogenetic analysis shows that BaCV clustered with yerba mate chlorosis-associated virus (YmCaV) and rice stripe mosaic virus (RSMV). Overall, our results provide strong evidence that BaCV is indeed a new virus species in the genus Cytorhabdovirus (family Rhabdoviridae), the first rhabdovirus to be identified infecting common bean. Full article