Dipartimento Scienze della Vita, Università di Siena, Siena, Italy.
Cytoskeleton (Hoboken). 2022 Jan;79(1-3):8-19. doi: 10.1002/cm.21713. Epub 2022 Jul 12.
The pollen tube is fundamental in the reproduction of seed plants. Particularly in angiosperms, we now have much information about how it grows, how it senses extracellular signals, and how it converts them into a directional growth mechanism. The expansion of the pollen tube is also related to dynamic cytoplasmic processes based on the cytoskeleton (such as polymerization/depolymerization of microtubules and actin filaments) or motor activity along with the two cytoskeletal systems and is dependent on motor proteins. While a considerable amount of information is available for the actomyosin system in the pollen tube, the role of microtubules in the transport of organelles or macromolecular structures is still quite uncertain despite that 30 years ago the first work on the presence of kinesins in the pollen tube was published. Since then, progress has been made in elucidating the role of kinesins in plant cells. However, their role within the pollen tube is still enigmatic. In this review, I will postulate some roles of kinesins in the pollen tube 30 years after their initial discovery based on information obtained in other plant cells in the meantime. The most concrete hypotheses predict that kinesins in the pollen tube enable the short movement of specific organelles or contribute to generative cell or sperm cell transport, as well as mediate specific steps in the process of endocytosis.
花粉管在种子植物的繁殖中起着基础性的作用。特别是在被子植物中，我们现在已经获得了很多关于花粉管如何生长、如何感知细胞外信号以及如何将其转化为定向生长机制的信息。花粉管的扩展也与细胞质动态过程有关，这些过程基于细胞骨架（例如微管和肌动蛋白丝的聚合/解聚）或沿两个细胞骨架系统的马达活性，并且依赖于马达蛋白。尽管 30 年前发表了第一篇关于花粉管中驱动蛋白存在的工作，但对于花粉管中的肌球蛋白系统，细胞器或大分子结构的运输中微管的作用仍然相当不确定。从那时起，在阐明植物细胞中驱动蛋白的作用方面已经取得了进展。然而，它们在花粉管中的作用仍然是个谜。在这篇综述中，根据同时从其他植物细胞中获得的信息，我将在最初发现驱动蛋白 30 年后，对它们在花粉管中的一些作用进行推测。最具体的假设预测，花粉管中的驱动蛋白能够实现特定细胞器的短距离运动，或者有助于生殖细胞或精子细胞的运输，并介导胞吞作用过程中的特定步骤。
