Search Results (5)

Watermelon is one of the most important fruits in China, accounting for more than 70% of the world’s total output. Fusarium wilt of watermelon is the most common and serious disease in the cultivation of watermelon. It is mainly caused by Fusarium oxysporum f. sp. niveum (FoN), which has caused serious damage to the watermelon-planting industry. Some mycoviruses can reduce the pathogenicity of host pathogens and have the potential for biocontrol, so their application potential in the biological control of plant fungal diseases has attracted much attention. In this study, high-throughput sequencing was performed on 150 FoN strains isolated from three major watermelon-production areas (northern semi-arid area, northwestern arid area, and southern humid area) to detect the diversity of mycoviruses and to uncover new mycoviruses. The analysis identified 25 partial or complete genome segments representing eight previously undescribed mycoviruses. The existence of six mycoviruses was verified via RT-PCR. The southern humid area had the highest diversity of mycoviruses, with 15 species identified. Among these, 40% are dsRNA viruses and 33.3% belong to the family Chrysoviridae, representing the predominant viral type and family. In the northern semi-arid area, a total of 12 viral species were identified, among these 41.7% were +ssRNA viruses and 25% belonged to the family Mymonaviridae, constituting the main viral types and family. The northwestern arid area showed relatively low viral diversity, only containing three species. Two of these were +ssRNA viruses classified under the Mitoviridae and Potyviridae families. Notably, only one virus, Fusarium oxysporum f. sp. niveum Potyvirus 1 (FoNPTV1), was shared across all three areas. These findings reveal significant regional differences in the mycoviral species composition and distribution, highlighting the complex interactions between mycoviruses and FoN in different environments. By uncovering new mycoviruses associated with FoN, this study provides valuable resources for the potential biocontrol of Fusarium wilt in watermelon, contributing to sustainable disease management and improving the quality and safety of watermelon production in China. Full article

Macrofungi play important roles in the soil elemental cycle of terrestrial ecosystems. Fungal viruses are common in filamentous fungi, and some of them can affect the growth and development of hosts. However, the composition and evolution of macrofungal viruses are understudied. In this study, ninety strains of Trametes versicolor, Coprinellus micaceus, Amanita strobiliformis, and Trametes hirsuta were collected in China. Four mixed pools were generated by combining equal quantities of total RNA from each strain, according to the fungal species, and then subjected to RNA sequencing. The sequences were assembled, annotated, and then used for phylogenetic analysis. Twenty novel viruses or viral fragments were characterized from the four species of macrofungi. Based on the phylogenetic analysis, most of the viral contigs were classified into ten viral families or orders: Barnaviridae, Benyviridae, Botourmiaviridae, Deltaflexiviridae, Fusariviridae, Hypoviridae, Totiviridae, Mitoviridae, Mymonaviridae, and Bunyavirales. Of these, ambi-like viruses with circular genomes were widely distributed among the studied species. Furthermore, the number and overall abundance of viruses in these four species of macrofungi (Basidiomycota) were found to be much lower than those in broad-host phytopathogenic fungi (Ascomycota: Sclerotinia sclerotiorum, and Botrytis cinerea). By employing metatranscriptomic analysis in this study, for the first time, we demonstrated the presence of multiple mycoviruses in Amanita strobiliformis, Coprinellus micaceus, Trametes hirsute, and Trametes versicolor, significantly contributing to research on mycoviruses in macrofungi. Full article

In this study, we identified Plasmopara-viticola-lesion-associated mononegaambi virus 3 (recently classified as Penicillimonavirus gammaplasmoparae), a fungi-associated mymonavirus, in grapevine plants showing an unusual upward curling symptomatology on the leaves and premature decline. Mymonaviridae is a family comprising nine genera of negative-sense single-stranded RNA viruses infecting filamentous fungi, although few of them have been associated with oomycetes, plants, and insects. Although the first mymonavirus genome description was reported a decade ago, the genome organization of several genera in the family, including the genus Penicillimonavirus, has remained unclear to date. We have determined the complete genome of P. gammaplasmoparae, which represents the first complete genomic sequence for this genus. Moreover, we provide strong evidence that P. gammaplasmoparae genome is bipartite and comprises two RNA molecules of around 6150 and 4560 nt. Our results indicate that the grapevine powdery mildew pathogen, Erysiphe necator, was also present in the analyzed plants and suggest P. gammaplasmoparae could be infecting this fungus. However, whether the fungus and/or the mycovirus are associated with the symptomatology that initially prompted these efforts remains to be determined. Full article

Alternaria fungus can cause notable diseases in cereals, ornamental plants, vegetables, and fruits around the world. To date, an increasing number of mycoviruses have been accurately and successfully identified in this fungus. In this study, we discovered mycoviruses from 78 strains in 6 species of the genus Alternaria, which were collected from 10 pear production areas using high-throughput sequencing technology. Using the total RNA-seq, we detected the RNA-dependent RNA polymerase of 19 potential viruses and the coat protein of two potential viruses. We successfully confirmed these viruses using reverse transcription polymerase chain reaction with RNA as the template. We identified 12 mycoviruses that were positive-sense single-stranded RNA (+ssRNA) viruses, 5 double-strand RNA (dsRNA) viruses, and 4 negative single-stranded RNA (−ssRNA) viruses. In these viruses, five +ssRNA and four −ssRNA viruses were novel mycoviruses classified into diverse the families Botourmiaviridae, Deltaflexivirus, Mymonaviridea, and Discoviridae. We identified a novel −ssRNA mycovirus isolated from an A. tenuissima strain HB-15 as Alternaria tenuissima negative-stranded RNA virus 2 (AtNSRV2). Additionally, we characterized a novel +ssRNA mycovirus isolated from an A. tenuissima strain SC-8 as Alternaria tenuissima deltaflexivirus 1 (AtDFV1). According to phylogenetic and sequence analyses, we determined that AtNSRV2 was related to the viruses of the genus Sclerotimonavirus in the family Mymonaviridae. We also found that AtDFV1 was related to the virus family Deltaflexivirus. This study is the first to use total RNA sequencing to characterize viruses in Alternaria spp. These results expand the number of Alternaria viruses and demonstrate the diversity of these mycoviruses. Full article

Here, we characterized a negative single-stranded (−ss)RNA mycovirus, Botrytis cinerea mymonavirus 1 (BcMyV1), isolated from the phytopathogenic fungus Botrytis cinerea. The genome of BcMyV1 is 7863 nt in length, possessing three open reading frames (ORF1–3). The ORF1 encodes a large polypeptide containing a conserved mononegaviral RNA-dependent RNA polymerase (RdRp) domain showing homology to the protein L of mymonaviruses, whereas the possible functions of the remaining two ORFs are still unknown. The internal cDNA sequence (10-7829) of BcMyV1 was 97.9% identical to the full-length cDNA sequence of Sclerotinia sclerotiorum negative stranded RNA virus 7 (SsNSRV7), a virus-like contig obtained from Sclerotinia sclerotiorum metatranscriptomes, indicating BcMyV1 should be a strain of SsNSRV7. Phylogenetic analysis based on RdRp domains showed that BcMyV1 was clustered with the viruses in the family Mymonaviridae, suggesting it is a member of Mymonaviridae. BcMyV1 may be widely distributed in regions where B. cinerea occurs in China and even over the world, although it infected only 0.8% of tested B. cinerea strains. Full article