Flowering induced by DNA demethylation in Perilla frutescens var. crispa

低温在春化过程中的持久效应受DNA去甲基化的调节。在光周期开花中，如果将植物移到不适宜的光周期条件下，光周期的影响就消失了。然而，短日照植物紫苏（Perilla frutescens var. crispa是个例外。本种一次诱导开花状态持续时间长。这表明可能参与的DNA去甲基化在开花的P. frutescens。1.以短日照植物紫苏（Perilla frutescens var.长日照条件下的crispa。从叶片中提取基因组DNA，用甲基化敏感的限制性内切酶Hpa II酶切，以25 S-18 S rDNA间隔区为探针进行Southern杂交分析。仅在5-氮杂胞苷处理的植物中检测到低分子片段。结果表明，5-氮胞苷处理引起了基因组DNA的去甲基化。3.茎尖分生组织的处理是在第4节叶片展开时进行的。甚至在较低的叶腋处也诱导了花序。这种间接效应可能是由于5-氮胞苷作用于较高节位的叶片，使其传递开花刺激物质所致。4. 5-氮胞苷处理也能诱导紫叶蝇子草开花。开花的诱导可能与光周期效应的持久记忆有关。

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.