Mycovirus-encoded suppressors of RNA silencing: Possible allies or enemies in the use of RNAi to control fungal disease in crops

Plants, fungi, and many other eukaryotes have evolved an RNA interference (RNAi) mechanism that is key for regulating gene expression the control of pathogens. RNAi inhibits expression, in a sequence-specific manner, by recognizing deploying cognate double-stranded (dsRNA) either from endogenous sources (e.g. pre-micro RNAs) or exogenous origin viruses, dsRNA, small interfering RNAs, siRNAs). Recent studies demonstrated fungal pathogens can transfer siRNAs into plant cells to suppress host immunity aid infection, termed cross-kingdom RNAi. New technologies, based on are being developed crop protection against insect pests, more recently One example, host-induced silencing (HIGS), which whereby transgenic plants modified produce dsRNAs targeting transcripts plants, their pests. An alternative regulation strategy also co-opts machinery spray-induced (SIGS), single-stranded RNAs (ssRNAs) applied target genes within pathogen pest. Fungi use mycoviruses (fungal viruses) deploy virus-encoded suppressors (myco-VSRs) as counter-defence. We propose myco-VSRs may impact new dsRNA-based management methods, resulting unintended outcomes, including suppression HIGS SIGS. Despite large diversity discovered using high throughput sequencing, biology poorly understood. In particular, prevalence cellular effect encoded VSRs under-appreciated when considering deployment SIGS strategies. This review focuses mycoviruses, VSR activities implications pathogenic fungi