Figure 9.

Proposed model to explain the DNA methylation pattern in castor bean endosperm and embryo. RcDME or RcROS1 removes the methylated cytosine at the genome scale (blue lollipops for CG, green lollipops for CHG, and red lollipops for CHH methylation), and demethylation leads to the generation of 24-nucleotide siRNAs that could guide de novo CHH DNA methylation by RcDRM2 in the endosperm and embryo. The insufficient expression of RcMET1 and RcCMT in the endosperm tissue, which maintain the CG and CHG methylation levels (denoted by looping arrows), results in reduced CG and CHG methylation (denoted by short-handled lollipops) compared with embryo (denoted by long-handled lollipops).