Table_3_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.

本研究旨在探究马兰科植物中花柱异常快速运动的组织学基础。尽管这种爆炸式授粉机制已受到众多研究的关注，但迄今为止，尚未进行过对体积变化的量化测量。基于物理参数和局限性（多孔弹性时间），花柱的运动本身的速度之快，远远超出了仅由膨压变化所能解释的范围。因此，我们提出了花柱内含有弹性结构以储存能量，从而实现快速运动的理论假设。我们以Goeppertia bachemiana为实验对象，提供了一种实验方法，以识别花柱在不同状态下的组织学差异，即稳定状态、未释放状态和释放状态。通过横切和纵切面，我们重建了花柱不同部位细胞的体积。在讨论组织学数据时，我们考虑了可能的水位变化（膨压运动）以及弹性不稳定性，这些不稳定性被提出用以解释马兰科植物的花柱运动。当前数据表明，在未释放状态下，上表皮受到拉伸应力。在花柱释放后，花柱的下侧显示出巨大的水分吸收。根据我们的研究结果，我们假设G. bachemiana中花柱的快速运动可能是基于弹性拉伸的上表皮，而下侧的“浸泡组织”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，诸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。