Characterization of siRNAs derived from rice stripe virus in infected rice plants by deep sequencing.

RNA interference is a natural defense against viruses in plants. To date, the only viral siRNAs characterized have been those for positive-sense RNA viruses with one or two genome components. Here, we characterized siRNAs derived from rice stripe virus (RSV), a member of the genus Tenuivirus with four genomic RNAs and an ambisense coding strategy. Deep sequencing of small RNAs from infected rice leaves showed that siRNAs were derived almost equally from virion and complementary RNA strands and were mostly 20-22 nucleotides long. Most viral siRNAs were produced within the coding sequences and 5' termini of the RSV genome. RSV siRNAs had a higher G and lower C content than the viral genome but a strong A/U bias at the first nucleotide and a U bias at the final one, suggesting preferential targeting of such sequences by rice Dicer-like proteins.