Oyster Mushroom Spherical Virus Crosses the Species Barrier and Is Pathogenic to a New Host Pleurotus pulmonarius

Abstract

Oyster mushroom spherical virus (OMSV) is a mycovirus with a positive-sense single-stranded RNA genome that infects the edible mushroom Pleurotus ostreatus. OMSV is horizontally transferred from an infected strain to a cured strain via mycelia. The infection results in significant inhibition of mycelial growth, malformation of fruiting bodies, and yield loss in oyster mushrooms. This study successfully transferred OMSV from P. ostreatus to Pleurotus pulmonarius. However, transmission was not successful in other Pleurotus species including P. citrinopileatus, P. eryngii, P. nebrodensis, and P. salmoneostramineus. The successful OMSV infection in P. pulmonarius was further verified with Western blot analysis using a newly prepared polyclonal antiserum against the OMSV coat protein. Furthermore, OMSV infection reduced the mycelial growth rate of P. pulmonarius. The OMSV-infected strain demonstrated abnormal performance including twisted mushrooms or irregular edge of the cap as well as reduced yield of fruiting bodies in P. pulmonarius, compared to the OMSV-free strain. This study is the first report on the infection and pathogenicity of OMSV to the new host P. pulmonarius. The data from this study therefore suggest that OMSV is a potential threat to P. pulmonarius.

Transmission of Oyster Mushroom Spherical Virus to Progeny via Basidiospores and Horizontally to a New Host Pleurotus floridanus

“…The Cryphonectria nitschkei chrysovirus 1 can be horizontally transmitted from its original host C. nitschkei to C. radicalis and C. naterciae strains [ 33 ]. A previous study conducted by the authors confirmed the horizontal transmission capability of the OMSV Chinese strain (OMSV-Ch) from P. ostreatus 8129 to P. pulmonarius strain XH2208 via mycelial contact [ 27 ]. In this study, OMSV-infected P. pulmonarius was co-cultured with other strains of Pleurotus species, revealing that OMSV could indeed spread horizontally from P. pulmonarius to P. floridanus .…”

“…A previous study demonstrated that OMSV could be horizontally transmitted via mycelia [ 27 ]. Two OMSV-infected strains, P. ostreatus strain 8129 and P. pulmonarius strain XH2208, were cultivated to investigate the possibility of vertical transmission through sexual basidiospores.…”

“…The Pleurotus ostreatus ASI2792 mycovirus (PoV-ASI2792) has been reported to slow down mycelial growth and cause yield loss in the fruiting bodies of P. ostreatus [ 38 ]. More recently, it was shown that OMSV-Ch inhibited mycelial growth, induced dysmorphic symptoms in fruiting bodies, and reduced mushroom yield in both P. ostreatus and P. pulmonarius [ 27 ]. In the present study, the OMSV infection in P. floridanus resulted in a slowdown of mycelial growth and a decrease in mushroom yields.…”

“…Although the exact mechanisms underlying OMSV pathogenicity remain unclear, Previously, it was reported that the infection of PoV in P. ostreatus affects mycelial growth and fruiting body formation by directly reducing gene expression and then impairing the activity of some extracellular enzymes [ 38 ]. The OMSV infection reduced the carboxymethyl cellulase and laccase activity in the P. pulmonarius strain [ 27 ]. Further studies concerning the relative expression levels of genes and the activity levels of other extracellular enzymes such as amylase, aspartic protease, cellulase, chitinase, β-glucosidase, lipase, manganese peroxidases, polygalacturonase, and xylanase are necessary to investigate.…”

“…Previous studies found that OMSV could be transmitted horizontally from an infected strain to a virus-cured strain by hyphae in P. ostreatus strain 8129, resulting in slowed mycelial growth, malformations of the fruiting bodies, and yield loss [ 26 ]. Interestingly, the OMSV could also cross the species barrier and horizontally transmit from P. ostreatus to P. pulmonarius [ 27 ]. However, no studies have investigated the vertical transmission of OMSV.…”