<p>(A) Schematic representation of the maize rRNA genes and the positions of analyzed amplicons. (B) ActD treatment induced site-specific hypomethylation within the 45S rDNA promoter. The y-axis indicated the ratio of the clones with methylation sites and the x-axis indicated positions of CpG dinucleotides from −113 to +157. (C) ChIP analysis showed that the total level of histone H3 within 45S rDNA regions was decreased after treatment with 15 µg/ml ActD. DNA associated with histone H3 was immunoprecipitated with the anti-H3 antibody and primers specific for different region of 45S rDNAs were used to amplify DNA for quantitative real-time PCR. The y-axis values were the relative quantities of DNA and the x-axis indicated different regions of 45S rDNAs. Each experiment was repeated three times and the average value was shown with the SD. (D) ChIP analysis of levels of H3K9ac, H3K9me2, H3K4me2, H4K5ac and H4K16ac within 45S rDNA regions in maize after treatment without or with 15 µg/ml ActD. DNA associated with different histone modifications was immunoprecipitated with the related antibody and primers specific for different regions of the 45S rDNA were used to amplify DNA for quantitative real-time PCR. The y-axis indicated the ratio of the relative quantities of DNA in maize with ActD treatment to the relative quantities of DNA in maize without ActD treatment. Relative values were normalized to those of the total H3.The x-axis indicated different regions of 45S rDNAs. Each experiment was repeated three times and the average value was shown with the SD.</p
