Biogenesis and Biological Activity of Secondary siRNAs in Plants
Figure 9
Cascades involving TAS1 and TAS2 processing in Arabidopsis. The results rely on the use of CaMV infected plants of which the suppressor TAV interferes with the DCL4/DRB4 activity. The dsRNA intermediates generated by RDR6 accumulating in CaMV infected plants were analyzed. For TAS1c, three main dsRNAs accumulated. The largest and minor one corresponds to a single cut of TAS1c RNA by the AGO1::mir173 RISC, the second one from a double hit by AGO1::miR173 and AGO1::, and the third one by AGO1::miR173 and AGO1(2)::. and are siRNAs at positions 6 and 10 derived from the antisense strand of the dsRNA intermediate. exists as a 21nt 5′A form likely bound to AGO2 and a 22nt 5′U form bound to AGO1. Notably, RISCs can also target TAS1a, TAS1b, and TAS2 RNAs. On the right, a gel ss showed separating single and double-stranded ta-siRNA precursors (S sense RNAs, AS, antisense RNAs).
