Flowering induced by DNA demethylation in Perilla frutescens var. crispa

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The long-lasting effect of low temperature in vernalization is regulated by DNA demethylation. In photoperiodic flowering, the effect of photoperiodic cycle disappears if the plants were moved to unsuitable photoperiodic condition. However, a short-day plant, Perilla frutescens var. crispa is an exception. Once-induced flowering state of lasts long in this species. This suggests a possible involvement of DNA demethylation in the flowering of P.frutescens. Accordingly, the possible involvement of DNA demethylation in the regulation of flowering in P.frutescens was studied.1.A DNA demethylating reagent, 5-azacytidine was treated to a short-day plant, Perilla frutescens var. crispa under a long-day condition. The treatment caused flowering, suggesting that DNA demethylation induced flowering.2.The genomic DNAs were isolated from the leaves, digested with a methylation-sensitive restriction enzyme, Hpa II, and then Southern hybridization analysis was performed with a probe, 25S-18S rDNA intergenic spacer region cloned from P.frutescens. Lower molecular fragments were detected only in the 5-azacytidine-treated plants. The result indicates that the 5-azacytidine treatment caused demethylation of the genomic DNA.3.The treatment of shoot apical meristem was performed when the leaves at the fourth node were unfolded. Floral inflorescences were induced even at the lower leaf axils. Such an indirect may be caused by flowering stimulus transported from the leaves at the higher nodes which were affected by 5-azacytidine.4.The treatment with 5-azacytidine induced flowering also in Silene armeria. of which flowering state lasted Ions The induction of flowering may be correlated with the long-lasting memory of photoperiodic effect.