Fundamental study on the breeding of blue flowers due to copigments in Japanese garden. Iris ensata Thunb.

本研究的目的是培育鸢尾蓝花。首先，对飞燕草苷3RGac5G甲基化进行遗传分析。结果表明，飞鸽苷3RGac5G的甲基化受显性基因mt控制。其次，阐明了锦葵苷3RGac5G-矮马甲苷3RGac5G型蓝紫色品种的发蓝效应的原因。malvidin 3RGac5G-petunidin 3RGac5G型品种花的颜色与pH值之间没有特别的关系。而各品种的λ max与黄酮含量呈极显著相关（r=0.887^<**>）。这表明蓝紫色品种的变蓝作用取决于花青素和黄酮之间的共色素作用。再次，利用花青苷、金盏花苷3RGac5G、牵牛花苷3RGac5G、飞鸽苷3RGac5G等金盏花主要色素进行体外共色素鉴定。这些花青素引起了共色素化，即由于异牡馨素浓度的增加，可见λ max的色移（蓝化效应），估计每个位移的幅度（DELTA λ max）为32 ~ 35 nm。此外，0.1mM马蹄莲素3RGac5G、0.07mM马蹄莲素3RGac5G和0.7mM异牡荆素混合物的吸收光谱与属于马蹄莲素3RGac5G-马蹄莲素3RGac5G型的淡紫色品种“休藤-二食”、“海kikai”和“Yakonotama”的新鲜外花被的吸收光谱非常接近。因此，这些结果表明，这些花青素与异牡荆苷之间的共色素作用导致了蓝紫色品种的颜色变蓝。最后，讨论了飞燕草苷3RGac5G与异牡荆素共色素的蓝花育种策略。

The objective of the present study was to breed blue flowers of Iris ensata. Firstly, genetic analysis was carried out for methylation of delphinidin 3RGac5G.The result showed that methylation of delphinidin 3RGac5G was controlled by a dominant gene, which is symbolized as Mt.Secondly, the cause of bluing effect on the flower color of the bluish purple varieties in malvidin 3RGac5G-petunidin 3RGac5G type was clarified. No particular relationship between colors and pH of flowers among the malvidin 3RGac5G-petunidin 3RGac5G type varieties was recognized. Among these varieties, however, ther was a significant correlation (r=0.887^<**>) between the lambda max and the flavone contents. This suggests that the bluing effect on the flower color of the bluish purple varieties is depended upon the copigmentation between anthocyanins and flavones. Thirdly, the in vitro identification of copigmentation was carried out using anthocyanins, malvidin 3RGac5G,petunidin 3RGac5G and delphinidin 3RGac5G which are major pigments of I.ensata. These anthocyanins brought about copigmentation, i.e., bathochromic shift (bluing effect) of visible lambda max due to increased concentrations of isovitexin, and 32 to 35 nm were estimated as the magnitude (DELTA lambda max) of each shift. In addition, the absorption spectrum of 0.1mM malvidin 3RGac5G,0.07mM petunidin 3RGac5G and 0.7mM isovitexin mixture closely matched those of the fresh outer perianths of the bluish purple varieties, 'Suiten-isshoku', 'Hekikai' and 'Yakonotama' which belong to the malvidin 3RGac5G-petunidin 3RGac5G type of I.ensata. Therefore, these results indicate that the bluing effect on the flower color of the bluish purple varieties is caused by the copigmentation between these anthocyanins and isovitexin. Finally, the breeding strategy of blue flowers due to copigmentation of delphinidin 3RGac5G with isovitexin was discussed.