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蓝花鸢尾。首先对飞燕草素3RGac 5G甲基化进行了遗传分析，结果表明飞燕草素3RGac 5G甲基化受一对显性基因控制，标记为Mt。其次，阐明了锦葵素3RGac 5G-矮牵牛素3RGac 5G型蓝紫色品种花色转蓝效应的原因。在锦葵素3RGac 5G-矮牵牛素3RGac 5G型品种中，花的颜色和pH之间没有特别的关系。在这些品种中，λ max与黄酮含量呈极显著正相关（r=0.887^**>）。这表明，蓝紫色品种的花色变蓝效应取决于花色苷和黄酮类化合物之间的共色素作用。第三，利用花青苷、锦葵色素3RGac 5G、矮牵牛色素3RGac 5G和飞燕草色素3RGac 5G这四种红领巾的主要色素进行了共色素化的体外鉴定。这些花色素苷引起共色素沉着，即，由于异牡荆素浓度的增加，可见λ max的红移（蓝化效应）和32 - 35 nm被估计为每个偏移的幅度（Δ λ max）。此外，0.1mMmalvidin3RGac5G、0.07mMpetunidin3RGac5G和0.7mMisovitexin混合物的吸收光谱与蓝紫色品种“水天一种”、“平海”和“Yakonotama”的新鲜外花被的吸收光谱非常接近，它们属于I. ensata的malvidin 3RGac 5G-petunidin 3RGac 5G型。因此，这些结果表明，蓝紫色品种的花色变蓝效应是由这些花色苷和异牡荆素之间的共色素作用引起的。最后，对飞燕草素3RGac 5G与异牡荆素共着色的蓝色花育种策略进行了讨论。

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.