Table_4_Insights Into the Inside – A Quantitative Histological Study of the Explosively Moving Style in Marantaceae.docx

This study aims to identify the histological basis for the extraordinary, fast movement of the style in Marantaceae. Although this explosive pollination mechanism was subject of many studies, quantitative measurements to document volumetric changes have never been conducted. Based on physical parameters and limitations (poroelastic time), the movement itself is by far too fast to be explained by turgor changes solely. Therefore, we address the hypothesis that the style contains elastic structures to store energy allowing the fast movement. We provide an experimental approach in Goeppertia bachemiana to identify histological differences of styles in various states, i.e., steady, unreleased, and released state. Cross and longitudinal sections were used to reconstruct the cell volume in different sectors of the style. Histological data were discussed with respect to a putative water shift (turgor movement) and elastic instabilities that were proposed to explain the style movement of Marantaceae. Current data show, that the upper epidermis is under tensile stress in the unreleased state. After style release, the lower side of the style revealed an enormous water up-take. According to our results, we hypothesize that the fast style movement of G. bachemiana is likely based on an elastically stretched upper epidermis, whereas a “soaking tissue” at the lower side presumably mediates the up curling of the style. The experimental data show that at least for G. bachemiana, physical limitations such as the poroelastic time are suitable parameters to predict movements that are based on elastic instabilities.

本研究旨在揭示马鞭草科植物中花柱异常快速移动的形态学基础。尽管这种爆炸式传粉机制已受到众多研究者的关注，但从未进行过定量测量以记录体积变化。基于物理参数和限制（多孔弹性时间），花柱的移动速度之快，远远超出了仅由膨压变化所能解释的范围。因此，我们提出了一个假设，即花柱内含有弹性结构以储存能量，从而允许其快速移动。我们采用了一种实验方法，在Goeppertia bachemiana中识别花柱在不同状态下的形态学差异，即稳定状态、未释放状态和释放状态。通过横截面和纵截面重建了花柱不同部位的细胞体积。在讨论形态学数据时，我们考虑了可能的水分转移（膨压移动）和弹性不稳定性，这些被提出用以解释马鞭草科植物花柱的移动。当前数据显示，在未释放状态下，上部表皮处于拉伸应力之下。花柱释放后，花柱的下侧表现出巨大的水分吸收。根据我们的研究结果，我们假设G. bachemiana中花柱的快速移动可能是基于弹性拉伸的上表皮，而下侧的“吸水组织”可能介导了花柱的上卷曲。实验数据表明，至少对于G. bachemiana而言，如多孔弹性时间等物理限制是预测基于弹性不稳定性运动的有效参数。