Pointillist structural color in Pollia fruit
Pointillist structural color in Pollia fruit
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DOI：
10.1073/pnas.1210105109
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发表时间：
2012-09-25
影响因子：
11.1
通讯作者：
Steiner, Ullrich
中科院分区：
文献类型：
--
作者：
Vignolini, Silvia;Rudall, Paula J.;Steiner, Ullrich
通过结构颜色进行生物交流至少已有5亿年的历史。结构色在动物界中很常见，但在植物中的研究很少。我们提出了一个显著的例子，多层为基础的强烈虹彩着色的植物，在水龙果树的果实。这种颜色是由螺旋形堆积的纤维素微纤维的布拉格反射引起的，这些纤维在外果皮的细胞壁中形成多层。我们证明了动物和植物已经一致地进化出基于多层的光子结构，以使用完全不同的材料来产生颜色。这种水果的亮蓝色比之前描述的任何生物材料都要强烈。在自然界中独一无二的是，反射的颜色因多层堆叠中的层厚度不同而不同，使水果具有显著的像素化或点状外观。由于多层膜的形成同时具有螺旋性，光学特性显示来自每个表皮细胞的反射光被向左或向右圆偏振，这是以前从未在单个组织中观察到的特征。
Biological communication by means of structural color has existed for at least 500 million years. Structural color is commonly observed in the animal kingdom, but has been little studied in plants. We present a striking example of multilayer-based strong iridescent coloration in plants, in the fruit of Pollia condensata. The color is caused by Bragg reflection of helicoidally stacked cellulose microfibrils that form multilayers in the cell walls of the epicarp. We demonstrate that animals and plants have convergently evolved multilayer-based photonic structures to generate colors using entirely distinct materials. The bright blue coloration of this fruit is more intense than that of any previously described biological material. Uniquely in nature, the reflected color differs from cell to cell, as the layer thicknesses in the multilayer stack vary, giving the fruit a striking pixelated or pointillist appearance. Because the multilayers form with both helicoidicities, optical characterization reveals that the reflected light from every epidermal cell is polarized circularly either to the left or to the right, a feature that has never previously been observed in a single tissue.