Figure 1.

HAC1 expression is repressed by sugars. Wild-type Arabidopsis seeds were surface sterilized and then incubated in the dark at 4°C for 3 days prior to being sown on nytex screens on Petri plates containing solid minimal Arabidopsis media. The seeds were incubated under continuous light at room temperature for 20 h, and then the nytex screens and seeds were transferred to Petri plates containing Arabidopsis minimal media supplemented with 0.1 M sorbitol (Sorb), Glc, or Suc. After an additional 12–13 h, seeds were harvested, followed by isolation of RNA. The RNA was then used for qRT-PCR analysis. The transcript levels of ACT7 and UBQ6 were determined and the geometric means of their Ct used to normalize transcript levels. Transcript levels are expressed as ΔΔCt. ΔΔCt = ΔCt_HAC1 on sorbitol-Δ Ct_HAC1 on indicated media. ΔCt = Ct_HAC1 on indicated media-Ct_ACT7/UBQ6 on same media. Negative ΔΔCt values indicate that HAC1 transcript levels are lower in wild-type seeds germinating on the indicated media than in wild-type seeds germinating on sorbitol. Six technical replicates were performed for each biological replicate. Error bars indicate standard deviations. HAC1 expression on sorbitol vs. Glc or Suc differed with: ^**p < 0.05; or ^***p < 0.02, according to a Student's t-test. N = 3.