Identification of novel RNA mycoviruses from wild mushroom isolates in Japan

The characterization of viruses from environmental samples could aid in our understanding of their ecological significance and potential for biotechnological exploitation. While there has been much focus on pathogenic fungi or commercially cultivated mushrooms, attention to viruses from wild Basidiomycota mushrooms is lacking. Therefore, in this study, we conducted viral screening of fungal mycelia isolated from wild basidiocarps using agarose gel electrophoresis (AGE) and fragmented and primer-ligated dsRNA sequencing (FLDS). Among the 51 isolates, seven isolates were detected with virus-like bands during the initial screening with AGE, but only five isolates were detected with viruses after long-term storage. Using the FLDS method, we obtained seven viral genome sequences, including five double-stranded RNA (dsRNA) viruses belonging to Partitiviridae and Curvu-laviridae, one positive-sense single-stranded RNA (ssRNA) virus belonging to Endornaviridae and one negative -sense ssRNA virus belonging to Tulasviridae (Bunyavirales). All viruses characterized in this study are novel species. These findings greatly expanded our knowledge of the diversity of RNA viruses from environmental samples.

Automated summary

In this study, viral screening of wild basidiomycota mushrooms was conducted using agarose gel electrophoresis and dsRNA sequencing. Seven isolates with virus-like bands were detected during initial screening, and five isolates were still found to have viruses after long-term storage. By using the FLDS method, seven viral genome sequences belonging to different families, including Partitiviridae, Curvu-laviridae, Endornaviridae, and Tulasviridae, were obtained. All viruses characterized in this study are novel species, greatly expanding our knowledge of the diversity of RNA viruses from environmental samples.