Temperature-specific vsiRNA confers RNAi-mediated viral resistance at elevated temperature in Capsicum annuum.

R-mediated resistance is robust and efficient antiviral immune system in the plants. Thus, when R-mediated resistance was suppressed at elevated temperatures, the virus resistance was expected to be completely collapsed. Nonetheless, the multiplication of Tobacco mosaic virus pathotype P0 (TMV-P0) was inhibited, and TMV-P0 particles were only occasionally present in the systemic leaves of pepper plants (Capsicum annuum). RNAi-mediated RNA silencing is a well-known antiviral immune mechanism. At elevated temperatures, RNAi-mediated antiviral resistance was induced and virus-derived siRNAs (vsiRNAs) were dramatically increased. Through sRNA-sequencing (sRNA-Seq) analysis, we revealed that vsiRNAs derived from TMV-P0 were greatly increased. Intriguingly, virus-infected plants could select the temperature-specific vsiRNAs for antiviral resistance from the amplified vsiRNAs at elevated temperatures. The preapplication of these temperature-specific vsiRNAs endowed the plants antiviral resistance. The plants sustain antiviral resistance by activating RNAi-mediated resistance based on temperature-specific vsiRNAs at elevated temperatures.