A novel hexa‐segmented dsRNA mycovirus confers hypovirulence in the phytopathogenic fungus Diaporthe pseudophoenicicola

Abstract

A novel hexa-segmented double-stranded RNA (dsRNA) mycovirus was isolated and characterized from the filamentous phytopathogenic fungus Diaporthe pseudophoenicicola and was named Diaporthe pseudophoenicicola chrysovirus 1 (DpCV1). The full-length cDNAs of dsRNA1-6 were 3335, 3030, 3039, 2980, 963, and 780 bp, respectively. Sequence analysis indicated the presence of nine open reading frames (ORFs) in the DpCV1 genome. ORF1 in dsRNA1 putatively encoded the RNA-dependent RNA polymerase (RdRp) and ORF3 in dsRNA2 encoded a capsid protein (CP). The seven remaining ORFs, ORF2 in dsRNA2, ORF4 in dsRNA3, ORF6, seven in dsRNA4, ORF8 in dsRNA5, and ORF9 in dsRNA6, encoded proteins with unknown functions. Phylogenetic analysis revealed that DpCV1 is closely related to members of the cluster I group within the family Chrysoviridae but formed a separate clade. Importantly, all the six segments of DpCV1 were cured successfully through single spore isolation to obtain the isogenic virus-free strains. DpCV1 can confer hypovirulence to the fungal host of Diaporthe pseudophoenicicola. Compared with the virus-free strain, WC02 harbouring the DpCV1 is more sensitive to fungicide prochloraz. Furthermore, the cell wall of DpCV1 infected strain was loose and enlarged. This is the first report of a hexa-segmented tentative chrysovirus in D. pseudophoenicicola.

Community Series in Plants and Microbial Communities: Diversity, Pathogens and Biological Control, Volume II

“…Most known mycoviruses cryptically infect their hosts, but some mycoviruses can greatly affect their host, either by hypovirulence or hypervirulence. For example, the Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 can convert its host, Sclerotinia sclerotiorum, from a typical necrotrophic pathogen into a beneficial endophytic fungus (Zhang et al, 2020); infection with Nigrospora nonsegmented RNA virus 1 led to hypovirulence of Nigrospora oryzae on cotton leaves (Wang et al, 2022b); the Diaporthe pseudophoenicicola chrysovirus 1 can confer hypovirulence to the fungal host of Diaporthe pseudophoenicicola (Xu et al, 2022); and the virulence of Leptosphaeria biglobosa can be increased by the Leptosphaeria biglobosa quadrivirus 1 (Shah et al, 2020). The role of mycoviruses in the pathogenesis of fungi was welldiscussed in previous papers Bian et al, 2020;Kotta-Loizou, 2021).…”

Molecular characterization of a novel partitivirus isolated from Rhizoctonia solani

“…Most known mycoviruses cryptically infect their hosts, but some mycoviruses can greatly affect their host, either by hypovirulence or hypervirulence. For example, the Sclerotinia sclerotiorum hypovirulence–associated DNA virus 1 can convert its host, Sclerotinia sclerotiorum , from a typical necrotrophic pathogen into a beneficial endophytic fungus (Zhang et al, 2020 ); infection with Nigrospora non-segmented RNA virus 1 led to hypovirulence of Nigrospora oryzae on cotton leaves (Wang et al, 2022b ); the Diaporthe pseudophoenicicola chrysovirus 1 can confer hypovirulence to the fungal host of Diaporthe pseudophoenicicola (Xu et al, 2022 ); and the virulence of Leptosphaeria biglobosa can be increased by the Leptosphaeria biglobosa quadrivirus 1 (Shah et al, 2020 ). The role of mycoviruses in the pathogenesis of fungi was well-discussed in previous papers (Abdoulaye et al, 2019 ; Bian et al, 2020 ; Kotta-Loizou, 2021 ).…”