State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace, Xi'an Jiaotong University, Xi'an 710049, P. R. China.
Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, P. R. China.
Soft Matter. 2017 Apr 19;13(16):2919-2927. doi: 10.1039/c6sm01915c.
Fountain streaming is a typical microfluidic pattern in plant cells, especially for cells with a high aspect ratio such as pollen tubes. Although it has been found that fountain streaming plays crucial roles in the transport of nutrients and metabolites, the positioning of organelles and the mixing of cytoplasms, its implications for the fast tip growth of pollen tubes remain a mystery. To address this, based on the observations of asiatic lily Lilium Casablanca, we developed physical models for reverse fountain streaming in pollen tubes and solved the hydrodynamics and advection-diffusion dynamics of viscous Stokes flow in the shank and apical region of pollen tubes. Theoretical and numerical results demonstrated that the gradients of turgor pressure and concentration of wall materials along the length of pollen tubes provide undamped driving force and high-efficiency materials supply, which are supposed to contribute to the fast tip-growth of pollen tubes. The sample experimental results show that the tip-growth will be abnormal when the gradients of turgor pressure change under osmotic stress induced by different concentrations of PEG-6000 (a dehydrant).
涌泉流是植物细胞中一种典型的微流体模式，特别是对于高纵横比的细胞，如花粉管。尽管已经发现涌泉流在营养物质和代谢物的运输、细胞器的定位以及细胞质的混合中起着至关重要的作用，但它对花粉管快速尖端生长的影响仍然是一个谜。为了解决这个问题，我们基于对亚洲百合 Lilium Casablanca 的观察，为花粉管中的反向涌泉流开发了物理模型，并解决了花粉管柄部和顶端区域粘性 Stokes 流的流体动力学和对流扩散动力学。理论和数值结果表明，花粉管中壁材料的膨压和浓度沿着长度的梯度提供了无阻尼的驱动力和高效的材料供应，这有助于花粉管的快速尖端生长。样本实验结果表明，当渗透压变化引起不同浓度的 PEG-6000（脱水剂）时，膨压梯度的变化会导致花粉管的异常生长。
