Induction of flowering by DNA demethylation in Perilla frutescens and Silene armeria: Heritability of 5-azacytidine-induced effects and alteration of the DNA methylation state by photoperiodic conditions

The cytidine analogue 5-azacytidine (azaC), which causes DNA demethylation, induced flowering in the long-day plant Silene armeria and the short-day plant Perilla frutescens var. crispa under non-inductive photoperiodic conditions, suggesting that the expression of photoperiodic flowering-related genes is regulated by DNA methylation. The progeny of plants induced to flower by azaC did not flower under non-inductive photoperiodic conditions. The DNA gel blot hybridization analysis revealed no differences in the methylation states of genomic DNA from the azaC and control progeny in P. frutescens. These results suggest that the flowering-related genes activated by DNA demethylation were remethylated in the progeny. This remethylation system may allow the genes to be demethylated in response to inductive photoperiodic conditions in each generation. The azaC treatment also induced dwarfism in P. frutescens, and this characteristic was inherited by the progeny. Similar relationships between the azaC-induced dwarfism and the demethylation/remethylation system could not be established. Genome-wide methylation changes were examined by methylation-sensitive amplified fragment length polymorphism (MS-AFLP) analysis in P. frutescens, and the results showed that the DNA methylation state was altered by photoperiodic conditions.