The identification of a novel Pleurotus ostreatus dsRNA virus and determination of the distribution of viruses in mushroom spores

Abstract

Double-stranded RNAs and virus particles were identified in Pleurotus ostreatus strain Shin-Nong in Korea. Isometric virus particles with a diameter of 33 nm were purified, which are similar to other Pleurotus viruses reported previously. This strain contains 5 dsRNAs, 8.0, 2.5, 2.4, 2.0, and 1.8 kb in size. The virus particles contain 2 dsRNAs, designated RNA-1 (2.5 kb), and RNA-2 (2.4 kb) which is a typical pattern of Partitiviridae. A non-encapsidated dsRNA of about 8.0 kb also was identified. Partial cDNA from RNA-1 was cloned, and sequence analysis revealed that this gene codes for RdRp. The comparison of the sequence from partial cDNA clone showed 35% amino acid homology with the C-terminal end of the RdRp gene of Helicobasidum mompa virus and Rosalinia necatrix virus. Specific primers designed from the partial sequences successfully amplified RT-PCR product from the infected mycelium and a single spore culture. We used these primers to determine the pattern of distribution of viruses in spores. Of the 96 different single spore cultures generated from Shin-Nong strain, a specific RT-PCR product was identified in 25 cultures, indicating that about 26% of basidiospores contain viruses.

Viral Effects of a dsRNA Mycovirus (PoV-ASI2792) on the Vegetative Growth of the Edible Mushroom Pleurotus ostreatus

“…Infection with a mycovirus occasionally causes severe morphological and physiological changes in fungi, such as changes in growth rate, colony morphology, spore production, pigmentation, and virulence-related phenotypes [ 2 4 ]. Viral infection of P. otreatus are also revealed reduced mycelial growth, delayed fruiting body formation, decreased fruiting body yield, and malformed fruiting bodies [ 5 8 9 10 12 ]. However, virus-free and virus-infected isogenic lines, which have identical genetic backgrounds, are needed to investigation of mycovirus-fungal host interactions because noncoincidence genetic backgrounds of fungal strains can lead to different symptoms in response to infection with the same mycovirus [ 19 30 ].…”

“…The symptoms of viral infection in P. ostreatus are revealed by reduced mycelial growth, delayed fruiting body formation, decreased fruiting body yield, and malformed fruiting body. dsRNA mycoviruses from P. ostreatus in Korea and China were isolated and characterized [ 5 6 7 8 9 10 11 12 ]. P. ostreatus viral diseases have been associated with several reported mycoviruses such as oyster mushroom spherical virus [ 11 ], oyster mushroom isomeric virus (OMIV) I and II [ 9 12 ], and so on [ 10 ].…”

Particle and naked RNA mycoviruses in industrially cultivated mushroom Pleurotus ostreatus in China

“…Naked dsRNA segments around 8.0 kb had been found in P. ostreatus strain Shin-Nong (Kim et al 2008), P. ostreatus var. florida (van der Lende et al 1995), but their sequences were not determined.…”

Viruses infecting macrofungi

“…Although the sequence information of this virus is lacking, it is expected to be a distinct virus species. In a more recent study, another novel, asymptomatic 33 nm isometric virus particle having a bisegmented dsRNA genome was isolated from the healthy sporophores of Pleurotus ostreatus Shin Nong strain [39]. The virus was named Pleurotus ostreatus virus Shin-Nong (PoV-SN) and the phylogenetic analysis carried out with the partial sequence of the RdRp encoding RNA-1 genome segment revealed its closest relatives as the Helicobasidum mompa Virus and the Rosalina necatrix Virus which are member of the family Partitiviridae.…”