Figure 4

Double-stranded Gus RNA is detected in lines that produce small interfering RNAs (siRNAs). Total RNAs from hpGus transgenic lines was treated either with (+) or without (−) RNase One prior to RNA blot analysis. Hybridization with a full length Gus probe detected a 0.55 kb fragment only in strains which produce siRNAs (that is, S34 and S5). The 0.55 kb RNA fragment is derived from annealing of the complementary arms of hpGus precursor to form a 0.55 kb dsRNA fragment that is resistant to RNase One digestion. Shown below is the ethidium bromide-stained RNA gel used for hybridization, demonstrating equivalent loading and extensive RNA cleavage following RNase One digestion.