(A) Under warm temperatures (22 ˚C), CHH methylation levels in the ALN promoter are lower in vegetative and flower tissues. During gametogenesis, CHH methylation is established in the sperm cells as a result of tissue-specific expression of AGO6, thus promoting non-canonical RdDM, which involves RDR2, RDR6, AGO6 and AGO4 components but not Pol IV. The paternal allele CHH methylation is maintained during seed development, which is likely due to pollen- and seed-specific non-canonical RdDM activity. (B) Under cold temperatures (10 ˚C) AGO6 accumulation is stimulated in pre-fertilization ovular tissues, which can increase RDR6-RdDM-dependent maternal allele methylation of the POGO region upstream of ALN. Cold also enhances AGO6 accumulation in stamens and post-fertilization ovular tissues, which can further increase methylation of the POGO region in mature seeds. Suppression of ALN expression promotes seed dormancy.