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

Members of the genus Armillaria are widespread forest pathogens against which effective protection has not yet been developed. Due to their longevity and the creation of large-scale cloning of Armillaria individuals, the use of mycoviruses as biocontrol agents (BCAs) against these pathogens could be an effective alternative. This work describes the detection and characterization of viruses in Armillaria spp. collected in the Czech Republic through the application of stranded total RNA sequencing. A total of five single-stranded RNA viruses were detected in Armillaria ostoyae and A. cepistipes, including viruses of the family Tymoviridae and four viruses belonging to the recently described "ambivirus" group with a circular ambisense genome arrangement. Both hammerhead (HHRz) and hairpin (HpRz) ribozymes were detected in all the ambiviricot sequences. Armillaria viruses were compared through phylogenetic analysis and confirmed their specific host by direct RT-PCR. One virus appears to infect both Armillaria species, suggesting the occurrence of interspecies transmission in nature.

• Klíčová slova
• ambivirus, biological control, circular genetic elements, root rot, tymovirus, viruses,
• MeSH
• Armillaria * genetika   virologie   MeSH
• fylogeneze * MeSH
• genom virový * MeSH
• mykoviry * klasifikace   genetika   izolace a purifikace   MeSH
• nemoci rostlin virologie   mikrobiologie   MeSH
• RNA virová * genetika   MeSH
• RNA-viry genetika   klasifikace   izolace a purifikace   MeSH
• sekvenční analýza RNA MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika 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

Phytophthora cactorum is an important oomycetous plant pathogen with numerous host plant species, including garden strawberry (Fragaria × ananassa) and silver birch (Betula pendula). P. cactorum also hosts mycoviruses, but their phenotypic effects on the host oomycete have not been studied earlier. In the present study, we tested polyethylene glycol (PEG)-induced water stress for virus curing and created an isogenic virus-free isolate for testing viral effects in pair with the original isolate. Phytophthora cactorum bunya-like viruses 1 and 2 (PcBV1 & 2) significantly reduced hyphal growth of the P. cactorum host isolate, as well as sporangia production and size. Transcriptomic and proteomic analyses revealed an increase in the production of elicitins due to bunyavirus infection. However, the presence of bunyaviruses did not seem to alter the pathogenicity of P. cactorum. Virus transmission through anastomosis was unsuccessful in vitro.

• Klíčová slova
• Bunyaviridae, PEG 8000, Phytophthora cactorum, mycovirus, oomycetes, virus curing,
• MeSH
• bříza MeSH
• Bunyaviridae * MeSH
• Orthobunyavirus * MeSH
• Phytophthora * MeSH
• proteomika MeSH
• rostliny MeSH
• stanovení celkové genové exprese MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

We explored the virome of the "Phytophthora palustris complex", a group of aquatic specialists geographically limited to Southeast and East Asia, the native origin of many destructive invasive forest Phytophthora spp. Based on high-throughput sequencing (RNAseq) of 112 isolates of "P. palustris" collected from rivers, mangroves, and ponds, and natural forests in subtropical and tropical areas in Indonesia, Taiwan, and Japan, 52 putative viruses were identified, which, to varying degrees, were phylogenetically related to the families Botybirnaviridae, Narnaviridae, Tombusviridae, and Totiviridae, and the order Bunyavirales. The prevalence of all viruses in their hosts was investigated and confirmed by RT-PCR. The rich virus composition, high abundance, and distribution discovered in our study indicate that viruses are naturally infecting taxa from the "P. palustris complex" in their natural niche, and that they are predominant members of the host cellular environment. Certain Indonesian localities are the viruses' hotspots and particular "P. palustris" isolates show complex multiviral infections. This study defines the first bi-segmented bunya-like virus together with the first tombus-like and botybirna-like viruses in the genus Phytophthora and provides insights into the spread and evolution of RNA viruses in the natural populations of an oomycete species.

• Klíčová slova
• Phytophthora, RNA-sequencing, multiple viral infections, mycovirus, natural habitat, oomycetes, virus ecology, virus evolution, virus reservoirs,
• Publikační typ
• časopisecké články MeSH

During an oomycete survey in December 2015, 10 previously unknown Halophytophthora taxa were isolated from marine and brackish water of tidal ponds and channels in saltmarshes, lagoon ecosystems and river estuaries at seven sites along the Algarve coast in the South of Portugal. Phylogenetic analyses of LSU and ITS datasets, comprising all described Halophytophthora species, the 10 new Halophytophthora taxa and all relevant and distinctive sequences available from GenBank, provided an updated phylogeny of the genus Halophytophthora s.str. showing for the first time a structure of 10 clades designated as Clades 1-10. Nine of the 10 new Halophytophthora taxa resided in Clade 6 together with H. polymorphica and H. vesicula. Based on differences in morphology and temperature-growth relations and a multigene (LSU, ITS, Btub, hsp90, rpl10, tigA, cox1, nadh1, rps10) phylo-geny, eight new Halophytophthora taxa from Portugal are described here as H. brevisporangia, H. cele-ris, H. frigida, H. lateralis, H. lusitanica, H. macrosporangia, H. sinuata and H. thermoambigua. Three species, H. frigida, H. macrosporangia and H. sinuata, have a homothallic breeding system while the remaining five species are sterile. Pathogenicity and litter decomposition tests are underway to clarify their pathological and ecological role in the marine and brackish-water ecosystems. More oomycete surveys in yet undersurveyed regions of the world and population genetic or phylogenomic analyses of global populations are needed to clarify the origin of the new Halophytophthora species. Citation: Maia C, Horta Jung M, Carella G, et al. 2022. Eight new Halophytophthora species from marine and brackish-water ecosystems in Portugal and an updated phylogeny for the genus. Persoonia 48: 54 - 90. https://doi.org/10.3767/persoonia.2022.48.02..

• Klíčová slova
• Peronosporaceae, Phytophthora, breeding system, ecological role, evolution, lifestyle, oomycetes,
• Publikační typ
• časopisecké články MeSH

Phytophthora castaneae, an oomycete pathogen causing root and trunk rot of different tree species in Asia, was shown to harbor a rich diversity of novel viruses from different families. Four P. castaneae isolates collected from Chamaecyparis hodginsii in a semi-natural montane forest site in Vietnam were investigated for viral presence by traditional and next-generation sequencing (NGS) techniques, i.e., double-stranded RNA (dsRNA) extraction and high-throughput sequencing (HTS) of small RNAs (sRNAs) and total RNA. Genome organization, sequence similarity, and phylogenetic analyses indicated that the viruses were related to members of the order Bunyavirales and families Endornaviridae, Megabirnaviridae, Narnaviridae, Totiviridae, and the proposed family "Fusagraviridae." The study describes six novel viruses: Phytophthora castaneae RNA virus 1-5 (PcaRV1-5) and Phytophthora castaneae negative-stranded RNA virus 1 (PcaNSRV1). All six viruses were detected by sRNA sequencing, which demonstrates an active RNA interference (RNAi) system targeting viruses in P. castaneae. To our knowledge, this is the first report of viruses in P. castaneae and the whole Phytophthora major Clade 5, as well as of the activity of an RNAi mechanism targeting viral genomes among Clade 5 species. PcaRV1 is the first megabirnavirus described in oomycetes and the genus Phytophthora.

• Klíčová slova
• RNA interference, RdRp, dsRNA, forest pathogen, multiple viral infections, mycovirus, oomycetes, ssRNA,
• Publikační typ
• časopisecké články MeSH