ORF Ι of Mycovirus SsNSRV-1 is Associated with Debilitating Symptoms of Sclerotinia sclerotiorum

Abstract

We previously identified Sclerotinia sclerotiorum negative-stranded virus 1 (SsNSRV-1), the first (−) ssRNA mycovirus, associated with hypovirulence of its fungal host Sclerotinia sclerotiorum. In this study, functional analysis of Open Reading Frame Ι (ORF Ι) of SsNSRV-1 was performed. The integration and expression of ORF Ι led to defects in hyphal tips, vegetative growth, and virulence of the mutant strains of S. sclerotiorum. Further, differentially expressed genes (DEGs) responding to the expression of ORF Ι were identified by transcriptome analysis. In all, 686 DEGs consisted of 267 up-regulated genes and 419 down-regulated genes. DEGs reprogramed by ORF Ι were relevant to secretory proteins, pathogenicity, transcription, transmembrane transport, protein biosynthesis, modification, and metabolism. Alternative splicing was also detected in all mutant strains, but not in hypovirulent strain AH98, which was co-infected by SsNSRV-1 and Sclerotinia sclerotiorum hypovirus 1 (SsHV-1). Thus, the integrity of SsNSRV-1 genome may be necessary to protect viral mRNA from splicing and inactivation by the host. Taken together, the results suggested that protein ORF Ι could regulate the transcription, translation, and modification of host genes in order to facilitate viral proliferation and reduce the virulence of the host. Therefore, ORF Ι may be a potential gene used for the prevention of S. sclerotiorum.

Characterization of the Mycovirome from the Plant-Pathogenic Fungus Cercospora beticola

“…The infection of SsNSRV-1 leads to attenuated symptoms of the fungal host, including defective growth rate, abnormal colonial morphology, curled hyphal tips, and hypovirulence [ 53 ]. Later, it has also been proved that the integrity of SsNSRV-1 genome may be necessary to protect viral mRNA from splicing and inactivation by the host fungi [ 59 ]. However, to date there are still many unknown (−)ssRNA viruses and the properties of most reported (−)ssRNA viruses remains unknown.…”

Mycoviromic Analysis Unveils Complex Virus Composition in a Hypovirulent Strain of Sclerotinia sclerotiorum

“…According to our results, HC025 is a multiple-virus-infected strain. Researchers have only studied SsNSRV1 for its hypovirulence-associated function [ 14 , 55 ]; the other four mycoviruses have not been separately functionally researched. As shown in Figure 5 and Figure 6 , the virus-transmitted strain Ep-1PNA367V obtained all the viruses detected in HC025 except for the hypovirulence-associated virus SsNSRV1, and became abnormal with reduced growth rate and pathogenicity.…”

Botrytis cinerea type II inhibitor of apoptosis BcBIR1 enhances the biocontrol capacity of Coniothyrium minitans

“…The PCR product was purified and digested with Kpn I restriction enzyme. The digested fragments were cloned into Kpn I site located downstream of S. sclerotiorum EF‐1α promoter in the expression vector pCH‐EF (Gao et al., 2020). The recombinant plasmid was sequenced to confirm its integrity and transformed into competent EHA105 cells using electroporation.…”