Incidence of diverse dsRNA mycoviruses inTrichodermaspp. causing green mold disease of shiitakeLentinula edodes

Abstract

A total of 315 fungal isolates causing green mold disease were collected from contaminated artificial logs and sawdust bags used for cultivating shiitake Lentinula edodes in Korea and were analyzed for the presence of double-stranded RNA (dsRNA). dsRNA, which was purified using dsRNA-specific chromatography and verified by dsRNA-specific RNaseIII digestion, was detected in 32 isolates. The molecular taxonomy of dsRNA-infected isolates indicated that all isolates belonged to the Trichoderma spp.. The number and size of dsRNAs varied among isolates and the band patterns could be categorized into 15 groups. Although there were seven dsRNA groups observed in multiple isolates, eight groups were found to occur in single isolates. The most common dsRNA group, group VI, which contained a band of 10 kb, occurred in 10 isolates encompassing three species of Trichoderma Partial sequence analysis of two selected dsRNA groups revealed a high degree of similarity to sequences of a RNA-dependent RNA polymerase, hypothetical protein, and polyprotein genes of other hypoviruses such as Macrophomina phaseolina hypovirus 1, Trichoderma hypovirus, and Fusarium graminearum hypovirus 2, respectively, indicating the occurrence of mycoviruses in Trichoderma spp.. Northern blot analysis suggested that many different mycoviruses, which have not been identified yet, exist in Trichoderma.

A novel double-stranded RNA mycovirus isolated from Trichoderma harzianum

“…Jom-in and Akarapisan (2009) isolated two mycoviruses with sizes of 0.7 kb and 1.1 kb from Trichoderma spp., although their taxonomic status was not analysed or classified [31]. Yun et al (2016) noted that mycoviruses of Lentinula edodes are widespread in fungi [20]. They isolated 32 strains containing dsRNA from 315 Trichoderma strains, which were divided into 15 groups according to dsRNA electrophoresis patterns.…”

“…are anamorphic soil-borne filamentous fungi classified as belonging to phylum Ascomycota , class Sordariomycetes , order Hypocreales , and family Hypocreales. While they are well studied [19], their mycoviruses have not been sufficiently investigated [20].…”

Identification and Molecular Characterization of a Novel Partitivirus from Trichoderma atroviride NFCF394

“…The T. atroviride strain NFCF394 infected with mycovirus was isolated from substrates showing green mold symptoms collected from Korean shiitake farms [ 12 ]. Fungal isolates were maintained at 25 ˚C in the dark on potato dextrose agar (PDA).…”

“…Recently, the presence of various mycoviruses in Trichoderma spp. has been suggested in studies reporting variable dsRNA mycovirus incidence [ 12 ]. In addition, studies of the biological function of mycoviruses have been conducted [ 13 , 14 ].…”

Identification of a Novel Partitivirus of Trichoderma harzianum NFCF319 and Evidence for the Related Antifungal Activity

“…causing a green mold disease in shiitake mushroom ( Lentinula edodes ) and confirmed the presence of novel mycoviruses in these Trichoderma spp. ( Yun et al, 2016 ). Although infection of fungi by many mycoviruses is asymptomatic or cryptic ( Ghabrial, 1998 ), there are many cases of mycoviruses inducing viral-specific symptoms in the host and reduced fungal virulence, known as hypovirulence, is one of representative examples in phytopathogenic fungi ( Nuss, 2005 ).…”