Molecular Characterization of a Novel Strain of Fusarium graminearum Virus 1 Infecting Fusarium graminearum

Abstract

Fungal viruses (mycoviruses) have attracted more attention for their possible hypovirulence (attenuation of fungal virulence) trait, which may be developed as a biocontrol agent of plant pathogenic fungi. However, most discovered mycoviruses are asymptomatic in their hosts. In most cases, mycovirus hypovirulent factors have not been explored clearly. In this study, we characterized a ssRNA mycovirus in Fusarium graminearum strain HB56-9. The complete nucleotide genome was obtained by combining random sequencing and rapid amplification of cDNA ends (RACE). The full genome was 6621-nucleotides long, excluding the poly(A) tail. The mycovirus was quite interesting because it shared 95.91% nucleotide identities with previously reported Fusarium graminearum virus 1 strain DK21 (FgV1-DK21), while the colony morphology of their fungal hosts on PDA plates were very different. The novel virus was named Fusarium graminearum virus 1 Chinese isolate (FgV1-ch). Like FgV1-DK21, FgV1-ch also contains four putative open reading frames (ORFs), including one long and three short ORFs. A phylogenetic analysis indicated that FgV1-ch is clustered into a proposed family Fusariviridae. FgV1-ch, unlike FgV1-DK21, had mild or no effects on host mycelial growth, spore production and virulence. The nucleotide differences between FgV1-ch and FgV1-DK21 will help to elucidate the hypovirulence determinants during mycovirus–host interaction.

The Signatures of Natural Selection and Molecular Evolution in Fusarium graminearum Virus 1

“…A new asymptomatic strain FgV1-ch was recently isolated and characterized in China ( Zhang et al, 2020 ). Interestingly, FgV1-ch did not show strong virulence to the host (PH-1), despite slight differences in the colony morphology, mycelial growth rate, and the production of conidia between FgV1-ch-infected and virus-free strains of PH-1 ( Zhang et al, 2020 ).…”

“…A new asymptomatic strain FgV1-ch was recently isolated and characterized in China ( Zhang et al, 2020 ). Interestingly, FgV1-ch did not show strong virulence to the host (PH-1), despite slight differences in the colony morphology, mycelial growth rate, and the production of conidia between FgV1-ch-infected and virus-free strains of PH-1 ( Zhang et al, 2020 ). Regarding its sequence, FgV1-ch showed 95.91% nucleotide identities (6350/6621) with the reference sequence of FgV1 (Accession number; NC_006937.2 ) in the NCBI database, with 26 amino acid replacements ( Figure 2 ).…”

“…FgV1–4 were originally isolated from different host strains, i.e., FgV1 was isolated from F. graminearum strain DK21 ( F. boothii ; lineage 3), FgV2 from strain 98-8-60 ( F. asiaticum ; lineage 6), and FgV3 and FgV4 from strain DK3 ( F. graminearum sensu stricto ; lineage 7) ( Lee et al, 2014 ). In addition, two viruses that share high sequence similarity with FgV1 or FgV2 have been recently isolated in China (hereafter referred to as FgV1-ch and FgV-ch9, respectively) ( Zhang et al, 2020 ). Considering that the original host strains of FgV1–4 belong to different lineages in the Fusarium graminearum species complex (FGSG), a complex that includes eight and several additional phylogenetic lineages that cause Fusarium head blight (FHB), the potential of adaptive evolution in FgVs can be inferred ( Amarasinghe et al, 2019 ).…”

FpgMBV1 Alleviates The Pathogenicity of Fusarium Pseudograminearum to Wheat Plants: A Megabirnavirus Case Study

“…For instance, Cryphonectria parasitica hypovirus 1 (CHV1) has been used to control chestnut blight caused by Cryphonectria parasitica [9,10]. In Fusarium species, more than 30 mycoviruses have been identi ed and fully sequenced [9][10][11][12][13][14]. 4 mycoviruses were associated with hypovirulence of the host Fusarium, and notably, 3 viruses were from F. graminearum [15][16][17].…”

“…dianthi showed decreased colonizing e ciency when compared to the virus-negative strain [18]. Fusarium graminearum virus 1 (FgV1) serves as a hypovirulence-associated virus in DK21 strain, while FgV1-ch, another mycovirues shared 95.91% identity in genome sequence with FgV1-DK21, had mild or no visible effects on host virulence and colonial morphology [14]. Comparative transcriptome and proteome analysis had provided many insights into understanding the interaction between virus and its host as well as the underlying mechanism of the mycovirus-mediated hypovirulence in fungi [19,20].…”