Figure 8.—

hpRNA transgene-induced silencing in 2n and 4n Arabidopsis. (A) Assay for EIN2 silencing in 2n and 4n Arabidopsis transformed with the EIN2 hpRNA construct. Longer hypocotyls indicate EIN2 silencing. (B) Pictures of seed from 2n and 4n Arabidopsis transformed with the chalcone synthase hpRNA construct. The reduction or loss of the brown pigmentation indicates CHS silencing. (C) Northern blot hybridization analysis of 2n and 4n hpCHS lines using ³²P-labeled bar antisense RNA as a probe. The lower panel is ethidium bromide-stained rRNA as a loading control. (D) Detection of siRNAs derived the hpCHS transgene in a subset of the 2n and 4n hpCHS lines. The number of + symbols indicates degrees of CHS silencing. The lower panel is U6 RNA hybridized with a ³²P-labeled antisense oligo as a loading control.