Phytophthora cinnamomi stands out as one of the most devastating plant pathogens worldwide, rapidly expanding its range and impacting a wide range of host species. In this study, we investigated the virome of P. cinnamomi across 222 isolates from Africa, Asia, Europe, Oceania, and the Americas using stranded total RNA sequencing, reverse transcription polymerase chain reaction screening, and Sanger sequencing of selected isolates. Our analysis revealed that virus infections were prevalent across all sampled populations, including RNA viruses associated with the orders Ghabrivirales, Martellivirales, and Tolivirales, and the classes Amabiliviricetes, Bunyaviricetes, and the recently proposed Orpoviricetes. Viruses were mainly found in East and Southeast Asian populations, within the geographic origin of P. cinnamomi but have also spread to new regions where the pathogen has emerged as a clonal destructive pathogen. Among the identified viruses, eight species, including two bunya-like viruses, one narna-like virus, and five ormycoviruses, exhibit a global distribution with some genetic divergence between continents. The interaction between P. cinnamomi and its virome indicates a dynamic coevolution across diverse geographic regions. Indonesia is indicated to be the viral epicentre of P. cinnamomi, with the highest intra- and interspecies diversity of viruses. Viral diversity is significantly enhanced in regions where sexual recombination of P. cinnamomi occurs, while regions with predominantly asexual reproduction harbour fewer viral species. Interestingly, only the partially self-fertile mating type (MAT) A2, associated with the global pandemic, facilitates the spread of viruses across different biogeographic regions, whereas viruses are absent in the self-sterile MAT A1 in its areas of introduction like Australia and South Africa. Intriguingly, the presence of a plant tombusvirus suggests a potential cross-kingdom infection among Chilean isolates and a plant host. This study sheds further light on the geographical origin of P. cinnamomi from a novel virome perspective.

• Klíčová slova
• HTS orphan contigs, forest emerging diseases, mating, oomycetes, virus diversity, virus evolution, virus–host coevolution,
• Publikační typ
• časopisecké články MeSH

Dothistroma septosporum and Dothistroma pini are severe foliar pathogens of conifers. They infect a broad spectrum of hosts (mainly Pinus spp.), causing chlorosis, defoliation of needles, and eventually the death of pine trees in extreme cases. Mycoviruses represent a novel and innovative avenue for controlling pathogens. To search for possible viruses hosted by Dothistroma spp. we screened a subset of isolates (20 strains of D. septosporum and one D. pini) originating from the Czech Republic, Slovenia, Italy, Austria and Ireland for viral dsRNA segments. Only five of them showed the presence of dsRNA segments. A total of 21 fungal isolates were prepared for total RNA extractions. RNA samples were pooled, and two separate RNA libraries were constructed for stranded total RNA sequencing. RNA-Seq data processing, pairwise sequence comparisons (PASC) and phylogenetic analyses revealed the presence of thirteen novel putative viruses with varying genome types: seven negative-sense single-stranded RNA viruses, including six bunya-like viruses and one new member of the order Mononegavirales; three positive-sense single-stranded RNA viruses, two of which are similar to those of the family Narnaviridae, while the genome of the third correspond to those of the family Gammaflexiviridae; and three double-stranded RNA viruses, comprising two novel members of the family Chrysoviridae and a potentially new species of gammapartitivirus. The results were confirmed with RT-PCR screening that the fungal pathogens hosted all the viruses and showed that particular fungal strains harbour multiple virus infections and that they are transmitted vertically. In this study, we described the narnavirus infecting D. pini. To our knowledge, this is the first virus discovered in D. pini.

• Klíčová slova
• Conifer pathogens, Dothistroma needle blight (DNB), High-throughput sequencing, Total RNA sequencing, Virus diversity,
• MeSH
• Ascomycota * virologie   genetika   MeSH
• borovice * mikrobiologie   MeSH
• dvouvláknová RNA genetika   MeSH
• fylogeneze * MeSH
• genom virový * MeSH
• mykoviry * genetika   klasifikace   izolace a purifikace   MeSH
• nemoci rostlin * virologie   mikrobiologie   MeSH
• RNA virová * genetika   MeSH
• RNA-viry genetika   klasifikace   izolace a purifikace   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH
• Itálie MeSH
• Názvy látek
• dvouvláknová RNA MeSH
• RNA virová * MeSH

Heterobasidion annosum sensu lato comprises some of the most devastating pathogens of conifers. Exploring virocontrol as a potential strategy to mitigate economic losses caused by these fungi holds promise for the future. In this study, we conducted a comprehensive screening for viruses in 98 H. annosum s.l. specimens from different regions of Czechia aiming to identify viruses inducing hypovirulence. Initial examination for dsRNA presence was followed by RNA-seq analyses using pooled RNA libraries constructed from H. annosum and Heterobasidion parviporum, with diverse bioinformatic pipelines employed for virus discovery. Our study uncovered 25 distinct ssRNA viruses, including two ourmia-like viruses, one mitovirus, one fusarivirus, one tobamo-like virus, one cogu-like virus, one bisegmented narna-like virus and one segment of another narna-like virus, and 17 ambi-like viruses, for which hairpin and hammerhead ribozymes were detected. Coinfections of up to 10 viruses were observed in six Heterobasidion isolates, whereas another six harbored a single virus. Seventy-three percent of the isolates analyzed by RNA-seq were virus-free. These findings show that the virome of Heterobasidion populations in Czechia is highly diverse and differs from that in the boreal region. We further investigated the host effects of certain identified viruses through comparisons of the mycelial growth rate and proteomic analyses and found that certain tested viruses caused growth reductions of up to 22% and significant alterations in the host proteome profile. Their intraspecific transmission rates ranged from 0% to 33%. Further studies are needed to fully understand the biocontrol potential of these viruses in planta.IMPORTANCEHeterobasidion annosum sensu lato is a major pathogen causing significant damage to conifer forests, resulting in substantial economic losses. This study is significant as it explores the potential of using viruses (virocontrol) to combat these fungal pathogens. By identifying and characterizing a diverse array of viruses in H. annosum populations from Czechia, the research opens new avenues for biocontrol strategies. The discovery of 25 distinct ssRNA viruses, some of which reduce fungal growth and alter proteome profiles, suggests that these viruses could be harnessed to mitigate the impact of Heterobasidion. Understanding the interactions between these viruses and their fungal hosts is crucial for developing effective, environmentally friendly methods to protect conifer forests and maintain ecosystem health. This study lays the groundwork for future research on the application of mycoviruses in forest disease management.

• Klíčová slova
• Heterobasidion annosum, growth rate, mycovirus, proteomics, root rot, ssRNA,
• MeSH
• Basidiomycota * MeSH
• fylogeneze MeSH
• genom virový MeSH
• mykoviry genetika   izolace a purifikace   MeSH
• nemoci rostlin virologie   mikrobiologie   MeSH
• RNA virová genetika   MeSH
• RNA-viry * genetika   izolace a purifikace   MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika epidemiologie   MeSH
• Názvy látek
• RNA virová MeSH

Here, we report the discovery and complete genome sequence of a novel virus, designated as "Phytophthora heveae alphaendornavirus 1" (PhAEV1), from a single isolate of the plant pathogenic oomycete Phytophthora heveae (kingdom Stramenipila) isolated from a tropical evergreen lowland rainforest in northern Vietnam. PhAEV1 was detected by both cellulose affinity chromatography of dsRNA and high-throughput sequencing of total RNA, and its presence and sequence were confirmed by RT-PCR and Sanger sequencing. The PhAEV1 genome, 12,820 nucleotides (nt) in length, was predicted to encode a single large polyprotein with the catalytic core domain of viral (superfamily 1) RNA helicase (HEL, amino acid [aa] positions 1,287-1,531), glycosyltransferase (GT, aa positions ca. 2,800-3,125), and RNA-directed RNA polymerase (RdRp, aa positions 3,875-4,112). PhAEV1 is the most similar to Phytophthora cactorum alphaendornavirus 3, sharing 39.4% and 39.1% nt and aa sequence identity, respectively. In addition to the first 5'-terminal AUG codon, three additional in-frame methionine codons were found in close proximity (nt 14-16, 96-98, and 176-178), suggesting potential additional translation initiation sites. Conserved RdRp motifs (A-E) similar to those detected in related endornaviruses were identified in PhAEV1, as well as in several previously described alphaendornaviruses from other Phytophthora species in which these motifs had not been identified previously. Phylogenetic analysis showed that PhAEV1 clusters with members of the genus Alphaendornavirus in the family Endornaviridae and is basal to two other alphaendornaviruses described from another oomycete, Phytophthora cactorum. PhAEV1 is the first virus reported in P. heveae.

• MeSH
• fylogeneze MeSH
• genom virový MeSH
• otevřené čtecí rámce MeSH
• Phytophthora * genetika   MeSH
• RNA virová genetika   MeSH
• RNA-dependentní RNA-polymerasa genetika   MeSH
• RNA-viry * genetika   MeSH
• sekvence aminokyselin MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• RNA virová MeSH
• RNA-dependentní RNA-polymerasa MeSH