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
• Geografické názvy
• Česká republika MeSH
• Itálie MeSH
• Názvy látek
• dvouvláknová RNA MeSH
• RNA virová * MeSH

The European race of the ascomycetous species Gremmeniella abietina (Lagerberg) Morelet includes causal agents of shoot blight and stem canker of several conifers in Europe and North America, which are known to host a diverse virome. GaRV6 is the latest and sixth mycovirus species reported within G. abietina. Before its description, one victorivirus and one gammapartitivirus species were described in biotype A, two mitoviruses in both biotypes A and B and a betaendornavirus in biotype B. Possible phenotypic changes produced by mycoviruses on G. abietina mycelial growth have been reported in Spanish mitovirus-free and GaRV6-hosting G. abietina isolates, which had higher growth rates at the optimal temperature of 15 °C, but no other major differences have been observed between partitivirus-like dsRNA and dsRNA-free isolates. In this review, we reappraise the diversity of viruses found in G. abietina so far, and their relevance in clarifying the taxonomy of G. abietina. We also provide evidence for the presence of two new viruses belonging to the families Fusariviridae and Endornaviridae in Spanish isolates.

• Klíčová slova
• Brunchorstia pinea, conifers, dsRNA, evolution, mycovirus, phylogeny, ssRNA,
• MeSH
• Ascomycota virologie   MeSH
• biodiverzita * MeSH
• cévnaté rostliny mikrobiologie   MeSH
• mykoviry klasifikace   izolace a purifikace   MeSH
• nemoci rostlin mikrobiologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Geografické názvy
• Evropa MeSH
• Severní Amerika MeSH

The population genetics of the family Partitiviridae was studied within the European race of the conifer pathogen Gremmeniella abietina. One hundred sixty-two isolates were collected from different countries, including Canada, the Czech Republic, Finland, Italy, Montenegro, Serbia, Spain, Switzerland, Turkey and the United States. A unique species of G. abietina RNA virus-MS1 (GaRV-MS1) appears to occur indistinctly in G. abietina biotypes A and B, without a particular geographical distribution pattern. Forty-six isolates were shown to host GaRV-MS1 according to direct specific RT-PCR screening, and the virus was more common in biotype A than B. Phylogenetic analysis based on 46 partial coat protein (CP) cDNA sequences divided the GaRV-MS1 population into two closely related clades, while RNA-dependent RNA polymerase (RdRp) sequences revealed only one clade. The evolution of the virus appears to mainly occur through purifying selection but also through recombination. Recombination events were detected within alignments of the three complete CP and RdRp sequences of GaRV-MS1. This is the first time that recombination events have been directly identified in fungal partitiviruses and in G. abietina in particular. The results suggest that the population dynamics of GaRV-MS1 do not have a direct impact on the genetic structure of its host, G. abietina, though they might have had an innocuous ancestral relationship.

• Klíčová slova
• Biotype, Brunchorstia pinea, Conifers, Evolutio, Mycoviruses, Partitiviridae,
• MeSH
• Ascomycota izolace a purifikace   virologie   MeSH
• fylogeneze MeSH
• genotyp MeSH
• molekulární evoluce MeSH
• molekulární sekvence - údaje MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• rekombinace genetická MeSH
• RNA virová genetika   MeSH
• RNA-viry klasifikace   genetika   izolace a purifikace   MeSH
• sekvenční analýza DNA MeSH
• sekvenční homologie MeSH
• shluková analýza MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Evropa MeSH
• Kanada MeSH
• Spojené státy americké MeSH
• Názvy látek
• RNA virová MeSH