Figure 9.

Model for RNA Silencing in the P_Suc2:PDS Line.

(A) In wild-type plants, we propose that two parallel pathways of PDS silencing and P_Suc2:PDS self-silencing operate through amplification by Pol IVa/CLSY1/RDR2 and siRNA production by DCL4. By contrast, the P_Suc2:PDS self-silencing pathway is proposed to function through Pol II, DCL3, and AGO4.

(B) In the absence of DCL3 or AGO4, transcription of the inverted repeat by Pol II and Pol IVa may lead to the production of excess siRNAs through DCL4 and increased PDS silencing.