The effect of zip-1, sgs3-11, and rdr6-11 on the accumulation of mRNAs, miRNAs, and siRNAs. (A) mRNA of ARF3/ETTIN, ARF4, and SPL3 accumulates in zip, sgs3-11, and rdr6-11. Total RNA from 2-week-old rosettes of plants grown in short days was hybridized with probes to the indicated genes. Actin was used as a loading control. (B) SPL3 mRNA is elevated in zip-1 at 15 and 18 d after planting. Blot of total RNA from shoot apices of wild-type and zip-1 rosettes hybridized with a probe to SPL3. 18S ribosomal RNA was used as a loading control. (C) The accumulation of miRNAs in zip-1, sgs3-11, and rdr6-11. Blots of low-molecular-weight RNA from 2-week-old mutant and wild-type plants hybridized with probes complementary to the functional strand of the indicated miRNAs. (D) The effect of zip-1, sgs3-11, and rdr6-11 on the level of endogenous sRNAs. Blots of low-molecular-weight RNA from 2-week-old mutant and wild-type plants hybridized with probes to the indicated sRNAs. U6 was used as a loading control. The intensity of each signal was measured using NIH Image; the ratio of this signal relative to wild-type is indicated below each image.