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| Rad35Leu2b-CMV is a spontaneous mutant from an attenuated strain FRad352b-CMV, which differs in a single amino acid from the 2b of FRad352b-CMV. FRad35Leu2b-CMV induced high pathogenicity and high viral progeny RNAs accumulation, even can revert the PTGS of GFP in the newly-developed leaves. We further show that the FRad35Leu2b-CMV inhibits the Nicotiana benthamiana AGO1-1, AGO4-1 transcription rather than FRad352b-CMV. Then we demonstrate that the PTGS suppressor (2bLeu) of FRad35Leu2b-CMV could not only suppress local gene silencing, but also suppress systemic gene silencing through blocking systemic movement of viral siRNA. Here we consider the 2bLeu interferes with the PTGS pathway by suppressing the movement of siRNAs. Taken together, we speculate that high virulence mediated by 2bLeu is achieved through blocking systemic movement of viral siRNA, and inhibiting RdDM by down-regulating AGO4-1, AGO1-1 expression. |
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| Keywords:silencing suppressor;siRNA;AGO;cucumber mosaic virus |
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