Fig. 6. zip-1 and rdr6-11 affect the amplitude of SPL3 expression, but not its temporal pattern. (A) Northern analysis of SPL3 and miR156 RNA in SD-grown plants at 14 dap (6 leaves) and 21 dap (12 leaves). zip-1 and rdr6-11 produce a modest increase in SPL3 mRNA without affecting the level of miR156. hst-6 reduces the accumulation of miR156 and produces a dramatic increase in SPL3 mRNA at 21 dap. U6 was used as a loading control for miR156 and 25S rRNA was the loading control for SPL3. (B) Northern analysis of SPL3 mRNA in SD-grown wild-type and mutant plants of different ages. Hybridization intensity was determined for three blots using NIH image, averaged and normalized to the intensity in wild-type plants at 14 dap. (C) GUS activity in the 3rd and 4th leaf of primary transgenic plants transformed with 35S::GUS-SPL3 (G-SPL3) or 35S::GUS-SPL3m (G-SPL3m). More than 30 plants of each genotype were analyzed. The difference between the expression of these constructs in wild type and zip-1 is not statistically significant. (D) Northern blot of SPL4, SPL9 and SPL15 mRNA in flowers of wild-type, sgs3-11 and rdr6-11 plants. (E) RT-PCR analysis of the SPL3 antisense transcript (SPL3 AS).