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蝴蝶兰的蓝花。首先对飞雀素3RGac5G的甲基化进行了遗传分析，结果表明，飞雀素3RGac5G的甲基化是由一个显性基因控制的，标记为mT。在Malvidin 3RGac5G-Petunidin 3RGac5G类型品种中，花的颜色与pH之间没有特殊的关系。然而，在这些品种中，最大吸收波长与总黄酮含量之间存在显著的相关性(r=0.887)。这表明蓝紫色品种花色的发蓝效应依赖于花色苷和黄酮类化合物之间的共着色剂。第三，对紫花菜的主要色素花青素、大黄素3RGac5G、花青素3RGac5G和飞雀素3RGac5G进行了体外共着色性鉴定。这些花色苷引起共着色，即由于异维黄素浓度的增加而导致可见的波长max的红移(蓝化效应)，每个位移的幅度(Delta Lambda Max)估计为32~35 nm。此外，0.1 mM的Malvidin 3RGac5G、0.07 mM的Petunidin 3RGac5G和0.7 mM的异黄皮苷混合物的吸收光谱与蓝紫色品种‘Suiten-ishoku’、‘Hekikai’和‘Yakonotama’的外花被鲜花被的吸收光谱非常接近，属于I.ensata的Malvidin 3RGac5G-Petunidin 3RGac5G类型。因此，这些结果表明，蓝紫色品种花色的发蓝效应是由这些花青素和异牡丹素之间的共着色剂引起的。最后，讨论了飞雀素3RGac5G与异维菌素共着色的蓝花育种策略。

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.