Characterization of siRNAs derived from cucumber green mottle mosaic virus in infected cucumber plants

Virus-derived small interfering RNAs (vsiRNAs) of cucumber green mottle mosaic virus (CGMMV), a member of the genus Tobamovirus, were characterised in cucumber plants by deep sequencing. CGMMV vsiRNAs of 21-22 nt in length predominated, suggesting that there might be a conserved mechanism of DCL2 and DCL4 involvement in the biogenesis of vsiRNAs, as well as a common RNA silencing pathway in CGMMV-infected cucumber plants. The 5'-terminal base of vsiRNAs was biased towards C/A/U, suggesting that CGMMV vsiRNAs might be loaded into diverse AGO-containing RISCs to disturb the gene expression of host plants. Possible targets for some of the vsiRNAs were also predicted.