An Overview of Mycoviral Curing Strategies Used in Evaluating Fungal Host Fitness

Abstract

The number of novel mycoviruses is increasing at a high pace due to advancements in sequencing technologies. As a result, an uncountable number of mycoviral sequences are available in public sequence repositories. However, only genomic information is not sufficient to understand the impact of mycoviruses on their host biology. Biological characterization is required to determine the nature of mycoviruses (cryptic, hypervirulent, or hypovirulent) and to search for mycoviruses with biocontrol and therapeutic potential. Currently, no particular selective method is used as the gold standard against these mycoviral infections. Given the importance of curing, we present an overview of procedures used in preparation of isogenic lines, along with their benefits and drawbacks. We concluded that a combination of single-spore isolation and hyphal tipping is the best fit for preparation of isogenic lines. Furthermore, recent bioinformatic approaches should be introduced in the field of mycovirology to predict virus-specific antivirals to get robust results. Graphical Abstract

Mycoviruses Increase the Attractiveness of Fusarium graminearum for Fungivores and Suppress Production of the Mycotoxin Deoxynivalenol

“…Such strains can be obtained by curing strains harboring mycoviruses or transmission into mycovirus-free strains. Our attempt to cure mycoviruses of strain 266 MV by ribavirin and cycloheximide failed (results not shown) and, indeed, varying success rates of this procedure have been reported [ 44 ]. An attempt to cure mycoviruses by mitotic segregation was more successful, resulting in the successful curing of two mycoviruses ( Table 2 ).…”

A Novel Strain of Fusarium oxysporum Virus 1 Isolated from Fusarium oxysporum f. sp. niveum Strain X-GS16 Influences Phenotypes of F. oxysporum Strain HB-TS-YT-1hyg

“…Virus-infected and virus-free isogenic lines are required for an effective investigation of the impact of a virus on its host, and the common method is to eliminate the virus from infected strains or introduce the virus into virus-free fungal isolates [48]. In this study, we used five methods (single-spore isolation, hyphal tipping, protoplast regeneration, cycloheximide treatment, and ribavirin treatment) to eliminate FoV1-FON from X-GS16, but we failed.…”

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 ].…”

“…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 ].…”