科学家发现了花粉颗粒折叠起来从而防止自身脱水的简单几何与机械原理。一旦花粉离开植株，它常常旅行很长的距离，而且面临脱水和杀死微小的花粉颗粒的干燥环境的威胁。尽管花粉颗粒在形状和结构上有很大差异，它们都拥有细胞壁，这种细胞壁是由不可渗透的外层（称为花粉粒外壁）组成，上面有可渗透的孔，能让花粉颗粒内部的分子物质出去。为了防止干燥，花粉表面经历了一种折叠过程，称为调节，这导致了密封的花粉颗粒，而可渗透的孔整齐地镶嵌在不可渗透的花粉粒外壁内部。Eleni Katifori及其同事使用计算机建模、数学分析和电子显微镜证明了花粉颗粒通过弯曲细胞表面而没有显著伸长从而折叠起来。根据这个发现，这组科学家预测了基于孔的数量和几何形状的三种类型的表面折叠。这组作者说这些结果为解释花粉多样性的功能意义提供了一个定量的框架。
论文 #09-11223: "Foldable structures and the natural design of pollen grains,” 作者 Eleni Katifori, Silas Alben, Enrique Cerda, David R. Nelson和Jacques Dumais
媒体联系人：Eleni Katifori，洛克菲勒大学物理和生物学研究中心
Center for Studies in Physics and Biology, Rockefeller University, New York, NY
电话：617-721-6209 (白天), 212-327-8861 (晚间)
电子邮件：ekatifori@mail.rockefeller.edu
Published online before print April 19, 2010, doi: 10.1073/pnas.0911223107
Abstract
Upon release from the anther, pollen grains of angiosperm flowers are exposed to a dry environment and dehydrate. To survive this process, pollen grains possess a variety of physiological and structural adaptations. Perhaps the most striking of these adaptations is the ability of the pollen wall to fold onto itself to prevent further desiccation. Roger P. Wodehouse coined the term harmomegathy for this folding process in recognition of the critical role it plays in the survival of the pollen grain. There is still, however, no quantitative theory that explains how the structure of the pollen wall contributes to harmomegathy. Here we demonstrate that simple geometrical and mechanical principles explain how wall structure guides pollen grains toward distinct folding pathways. We found that the presence of axially elongated apertures of high compliance is critical for achieving a predictable and reversible folding pattern. Moreover, the intricate sculpturing of the wall assists pollen closure by preventing mirror buckling of the surface. These results constitute quantitative structure-function relationships for pollen harmomegathy and provide a framework to elucidate the functional significance of the very diverse pollen morphologies observed in angiosperms.
