Figure 3.

PTGS Is Abolished Completely in the ago1-27 Mutant as in the sgs2 and sgs3 Mutants.

The ago1-27 mutant was compared with the L1 line, which shows PTGS of the 35S-uidA transgene, and with representative alleles of the sgs2 and sgs3 mutants deficient for PTGS (Mourrain et al., 2000).

(A) Transcript levels were determined using run-on analysis as described by Elmayan et al. (1998). Radiolabeled RNA extracted from nuclei from adult plants were hybridized to 2 μg of double-stranded DNA (pBS, empty pBluescript KS− vector; 25S, rDNA cloned in pBS; uidA, GUS gene cloned in pBS) and 2 μg of single-stranded DNA (sense, uidA−; antisense, uidA+). The signals of three independent experiments were quantified, and the ratios of uidA+ to 25S are indicated with standard deviations.

(B) RNA accumulation was measured by RNA gel blot analysis using 10 μg of total RNA. Note the faint band visible in the L1 lane with the uidA GUS probe. The signals were quantified, and the ratios of uidA to 25S are indicated.