Figure 3.

Viral defense pathway driven by host sRNAs and vsiRNAs. Once the virus infects plants, the vsiRNAs generated by DCLs establish the first line of defense in the infected proximal cells by guiding the virus transcript cleavage or mediating the methylation of virus DNA. VsiRNAs will transfer to distal cells and deliver antiviral RNAi with the help of RDRs. In this process, miRNAs and vasiRNAs produced by host plants will participate in the regulation of antiviral defense. Additional abbreviations: DCL, DICER-LIKE; DRBP, double-stranded RNA-binding protein; vsiRNA, virus-derived small interfering RNA; RISC, RNA-induced silencing complex; AGO, ARGONAUTE; RITS, RNA induced transcriptional silencing; Pol II, RNA polymerase II; miRNA, micro RNA; RDR, RNA-dependent RNA polymerase; SGS3, SUPPRESSOR OF GENE SILENCING 3; HEN1, HUA ENHANCER 1; vasiRNA, virus activated small interfering RNA; XRN4, EXORIBONUCLEASE 4; EIN5, ETHYLENE INSENSITIVE 5.