RNAi-Based Antiviral Innate Immunity in Plants

Abstract

Multiple antiviral immunities were developed to defend against viral infection in hosts. RNA interference (RNAi)-based antiviral innate immunity is evolutionarily conserved in eukaryotes and plays a vital role against all types of viruses. During the arms race between the host and virus, many viruses evolve viral suppressors of RNA silencing (VSRs) to inhibit antiviral innate immunity. Here, we reviewed the mechanism at different stages in RNAi-based antiviral innate immunity in plants and the counteractions of various VSRs, mainly upon infection of RNA viruses in model plant Arabidopsis. Some critical challenges in the field were also proposed, and we think that further elucidating conserved antiviral innate immunity may convey a broad spectrum of antiviral strategies to prevent viral diseases in the future.

P25 and P37 proteins encoded by firespike leafroll-associated virus are viral suppressors of RNA silencing

“…In plants, it has been shown that RNA silencing is a crucial immune system to preventing viral infections ( Yang and Li, 2018 ; Li et al, 2019 ; Jin et al, 2021 , 2022 ). To overcome the host immune system, plant viruses have developed various VSRs to inhibit RNA silencing at different steps ( Feng et al, 2018 ; Guo et al, 2019 ; Jin et al, 2021 , 2022 ).…”

“…In plants, it has been shown that RNA silencing is a crucial immune system to preventing viral infections ( Yang and Li, 2018 ; Li et al, 2019 ; Jin et al, 2021 , 2022 ). To overcome the host immune system, plant viruses have developed various VSRs to inhibit RNA silencing at different steps ( Feng et al, 2018 ; Guo et al, 2019 ; Jin et al, 2021 , 2022 ). Previous studies have shown that the most common counteraction of VSRs is to suppress vsiRNA amplification ( Guo et al, 2019 ; Li and Wang, 2019 ; Jin et al, 2022 ).…”

“…To overcome the host immune system, plant viruses have developed various VSRs to inhibit RNA silencing at different steps ( Feng et al, 2018 ; Guo et al, 2019 ; Jin et al, 2021 , 2022 ). Previous studies have shown that the most common counteraction of VSRs is to suppress vsiRNA amplification ( Guo et al, 2019 ; Li and Wang, 2019 ; Jin et al, 2022 ). In the present study, we demonstrated that FLRaV P25 could suppress PTGS at both the S-PTGS and the IR-PTGS levels ( Figures 3 , 5 ).…”

“…These vsiRNAs subsequently interact with argonaute proteins and form the RNA-induced silencing complexes to target the viral mRNAs and/or genomes for posttranscriptional gene silencing (PTGS) or transcriptional gene silencing (TGS) ( Yang and Li, 2018 ; Jin et al, 2021 ). Numerous studies have documented that plant RNA silencing is an essential immune system to defend against viral infections ( Szittya and Burgyán, 2013 ; Guo et al, 2019 ; Jin et al, 2021 , 2022 ). Frequently, plants defective in RNA silencing become susceptible to viral infections ( Carbonell et al, 2012 ; Qin et al, 2017 ; Kørner et al, 2018 ; Wang et al, 2021 ).…”

“…Frequently, plants defective in RNA silencing become susceptible to viral infections ( Carbonell et al, 2012 ; Qin et al, 2017 ; Kørner et al, 2018 ; Wang et al, 2021 ). To withstand the host RNA silencing, plant viruses have evolved various viral suppressors of RNA silencing (VSRs) to impede this response at different steps ( Yang and Li, 2018 ; Hussain et al, 2021 ; Jin et al, 2021 , 2022 ), such as P19 of tombusviruses ( Chapman et al, 2004 ), 2b of cucumoviruses ( Zhang et al, 2006 ), βC1, V2, and C4 proteins of geminiviruses ( Cui et al, 2005 ; Glick et al, 2008 ; Ismayil et al, 2018 ), VPg and HC-Pro proteins of potyviruses ( Rajamäki et al, 2014 ; Hafrén et al, 2018 ), and P3 of tenuiviruses ( Chen et al, 2020 ; Jiang et al, 2021 ).…”