Vertical Transmission of Fusarium circinatum Mitoviruses FcMV1 and FcMV2-2 via Microconidia

Abstract

Pine Pitch Canker disease, caused by the pathogenic fungus Fusarium circinatum, affects conifer species worldwide. However, the virulence of the pathogen may be affected by the presence of mycoviruses. The aim of this laboratory-based study was to investigate the probability and rate of transmission of F. circinatum mitoviruses FcMV1 and FcMV2-2 via microconidia. Ten isolates of mitovirus-infected F. circinatum were subcultured to produce a total of 100 single-spore colonies (ten replicates per isolate). The total RNA and cDNA obtained from each spore isolate (monosporic culture) were amplified by PCR with specific primers for detection of F. circinatum mitoviruses FcMV1 and FcMV2-2. The mitoviruses were detected in a high percentage of the individual spore isolates (between 60% and 100% depending on the fungal isolate). However, the probability of transmission was not statistically significantly associated with either the F. circinatum isolate or the viral strain. A high proportion of transmission via microconidia is critical for development of a biological control program against Pine Pitch Canker (PPC) disease in forests. However, further studies are needed to establish the effect of these mitoviruses on the virulence of F. circinatum.

Characterization of a Novel Mitovirus Infecting Melanconiella theae Isolated From Tea Plants

“…MtMV1 is efficiently transmitted through all conidia of strain WJB-5 (100 conidium-generated colonies were checked) in agreement with those mitoviruses detected in a high percentage of the individual spore isolates, as exemplified by Fusarium circinatum mitovirus 1 (FcMV1) and Fusarium circinatum mitovirus 2-2 (FcMV2-2) that showed vertical transmission rates between 60 and 100% depending on the fungal isolate (Romeralo et al, 2018), however, both Fusarium verticillioides mitovirus 1 (FvMV1) and Fusarium andiyazi mitovirus 1 strain 162 (FaMV1-162) showed 100% vertical transmission rate through fungal conidia (Jacquat et al, 2020). In contrast, some mycoviruses are less efficiently transmitted through conidia, as exemplified by Colletotrichum camelliae filamentous virus 1 (CcFV-1) and Pestalotiopsis theae chrysovirus-1 (PtCV1) (Jia et al, 2017;Zhou et al, 2021).…”

“…However, mitoviruses are initially found infecting fungi, they have recently been reported from plants as expected infectious entities ( Nibert et al, 2018 ; Nerva et al, 2019 ; Vong et al, 2019 ). They are transmitted through horizontal transmission (hyphal anastomosis and heterokaryosis) or vertical transmission (spores) ( Romeralo et al, 2018 ; Kamaruzzaman et al, 2019 ). Mitoviruses are the only viruses associated with the mitochondria in their hosts ( Cole et al, 2000 ; Osaki et al, 2005 ; Nibert, 2017 ; Fonseca et al, 2021 ) and often led to hypovirulence in their fungal hosts ( Nuss, 2005 ; Xu et al, 2015 ; Yang et al, 2018 ).…”

The Effect of Aspergillus Thermomutatus Chrysovirus 1 on the Biology of Three Aspergillus Species

“…An increase in linear growth due to virus infection was previously reported by Nuss [ 55 ] where C. parasitica (strain Euro7) cultures infected with Cryphonectria hypovirus 1 (CHV-1/Euro7) showed faster growth than the isogenic virus-free isolate. However, linear growth on agar plates does not necessarily correlate with total biomass production, as seen in our experiments for A. fumigatus , A. nidulans and A. niger ( Table 1 ), or with growth and/or pathogenicity in vivo [ 56 , 57 ].…”

A Novel Strain of Fusarium oxysporum Alternavirus 1 Isolated from Fusarium oxysporum f. sp. melonis Strain T-BJ17 Confers Hypovirulence and Increases the Sensitivity of Its Host Fungus to Difenoconazole and Pydiflumetofen

“…Mycoviruses utilize sexual (basidiospores and ascospores) or asexual spores (conidiophores) for their vertical transmission to the next generation, especially the asexual spores (conidiophores), which are most frequently used by mycoviruses for transmitting to progeny cells [56]. The transmission rate varies among different mycoviruses andd fungal isolates and depends on the age of the fungal colonies [46,[56][57][58]. Two mitoviruses, Fusarium verticillioides mitovirus 1 (FvMV1) and Fusarium andiyazi mitovirus 1 strain 162 (FaMV1-162), exhibited a 100% vertical transmission rate via spores, which infected F. verticillioides and F. andiyazi, respectively [46].…”