Quantitative Evaluation of the Contribution of Four Major Anthocyanins to Black Flower Coloring of Dahlia Petals
Quantitative Evaluation of the Contribution of Four Major Anthocyanins to Black Flower Coloring of Dahlia Petals
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DOI：
10.2503/hortj.mi-121
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发表时间：
2016-10-01
影响因子：
1.2
通讯作者：
Ohno, Sho
中科院分区：
文献类型：
--
作者：
Deguchi, Ayumi;Tatsuzawa, Fumi;Ohno, Sho
大丽花（Dahliavariabilis）的黑色花的颜色已被认为是由于高积累的花青素（Cy）为基础的花青素。对这种效应的一个可能的解释是，大丽花中基于Cy-based花青素比基于天竺葵色素（Pg）的花青素通过降低花瓣亮度（L*）和色度（C*）对黑色花的颜色贡献更大，但没有明显的证据被报道。在本研究中，大丽花花瓣中积累了四种主要的花青素，3，5-二葡萄糖苷（3，5diG）和3-对Pg和Cy的（6“-丙二酰葡萄糖苷）-5-葡萄糖苷（3 MG 5G）进行了纯化，并在不同pH下对它们的颜色进行了体外评价（3.0、4.0、4.5、5.0、5.5、6.0或7.0）和各种浓度（0.25、0.5、1.0、2.0或3.0 mg.mL（-1），pH 5.0或pH 3.0）。在与大丽花花瓣pH相近的pH 5.0和花色素苷相对稳定的pH 3.0下，Cy 3，5diG的L* 和C* 与Pg 3，5diG相近或高于Pg 3，5diG，表明Cy 3，5diG对黑色花着色的贡献并不比Pg 3，5diG大。另一方面，Cy 3 MG 5G的L* 和C* 显著低于Pg 3 MG 5G，特别是在2.0 mg·mL（-1）以上，表明Cy 3 MG 5G的贡献大于Pg 3 MG 5G。在不同比例的Pg和Cy的混合花色苷的颜色测量中观察到类似的趋势。Pg 3 MG 5G的L* 和C* 值远高于其他3种花色苷，因此认为其颜色是4种花色苷中离黑色最远的。9个品种中3 MG-5G型花色苷的积累量均远高于3，5diG型花色苷，但不同品种间Pg-和Cy-型花色苷的比例不同。考虑到这些结果，这表明，因为3 MG 5G型花色素苷主要积累在花瓣中，并且Cy 3 MG 5G比Pg 3 MG 5G对降低L* 和C* 具有显著更高的贡献，所以基于Cy的花色素苷的高积累对于大丽花的黑色着色是关键的。每种花色素苷的贡献被认为取决于结构;因此，鉴定对降低L* 和C* 具有最高贡献的花色素苷可以通过花色素苷在花瓣中的高积累在各种物种中产生黑色花。
The black flower color of dahlias (Dahlia variabilis) has been suggested to be attributed to a high accumulation of cyanidin (Cy)-based anthocyanins. A possible explanation for this effect is that Cy-based anthocyanins in dahlias contribute more to the black flower color than pelargonidin (Pg)-based anthocyanins by lowering petal lightness (L*) and chroma (C*), but no obvious evidence has been reported. In this study, four major anthocyanins accumulated in dahlia petals, 3,5-diglucoside (3,5diG) and 3-(6 ''-malonylglucoside)-5-glucoside (3MG5G) of Pg and Cy, were purified and their colors were evaluated in vitro at various pHs (3.0, 4.0, 4.5, 5.0, 5.5, 6.0, or 7.0) and various concentrations (0.25, 0.5, 1.0, 2.0, or 3.0 mg.mL(-1) at pH 5.0 or pH 3.0). The color of solution of purified anthocyanins varied depending on pH. At pH 5.0, which is approximately the same as pH of dahlia petals, and at pH 3.0, at which anthocyanins are relatively stable, the L* and C* of Cy 3,5diG were similar to or higher than those of Pg 3,5diG, suggesting that Cy 3,5diG did not contribute more to the black flower coloring than Pg 3,5diG. On the other hand, the L* and C* of Cy 3MG5G were significantly lower than those of Pg 3MG5G, particularly above 2.0 mg.mL(-1), suggesting that Cy 3MG5G contributed more than Pg 3MG5G. A similar tendency was observed in the color measurement of mixed anthocyanins in various proportion of Pg and Cy. The L* and C* of Pg 3MG5G were much higher than those of the other three anthocyanins; therefore, its color was considered to be the farthest from black among the four anthocyanins. The accumulated amount of 3MG5G-type anthocyanins was much higher than that of 3,5diG-type anthocyanins in all nine cultivars, although the proportion of Pg- and Cy-based anthocyanins varied among the cultivars. Considering these results, it was suggested that because 3MG5G-type anthocyanins predominantly accumulate in petals, and Cy 3MG5G has a significantly higher contribution to lowering L* and C* than Pg 3MG5G, the high accumulation of Cy-based anthocyanins is critical for the black flower coloring of dahlias. The contribution of each anthocyanin is considered to depend on the structure; therefore, identifying the anthocyanin with the highest contribution to lowering L* and C* may enable the production of black flowers in various species through the high accumulation of the anthocyanin in petals.