Department of Biology , University of Massachusetts , Amherst, MA 01003 , USA.
AoB Plants. 2011;2011:plr019. doi: 10.1093/aobpla/plr019. Epub 2011 Sep 8.
Pollen tubes grow by transferring chemical energy from stored cellular starch and newly assimilated sugars into ATP. This drives myriad processes essential for cell elongation, directly or through the creation of ion gradients. Respiration plays a central role in generating and regulating this energy flow and thus in the success of plant reproduction. Pollen tubes are easily grown in vitro and have become an excellent model for investigating the contributions of respiration to plant cellular growth and morphogenesis at the molecular, biochemical and physiological levels.
In recent decades, pollen tube research has become increasingly focused on the molecular mechanisms involved in cellular processes. Yet, effective growth and development requires an intact, integrated set of cellular processes, all supplied with a constant flow of energy. Here we bring together information from the current and historical literature concerning respiration, fermentation and mitochondrial physiology in pollen tubes, and assess the significance of more recent molecular and genetic investigations in a physiological context.
The rapid growth of the pollen tube down the style has led to the evolution of high rates of pollen tube respiration. Respiration rates in lily predict a total energy turnover of 40-50 fmol ATP s(-1) per pollen grain. Within this context we examine the energetic requirements of cell wall synthesis, osmoregulation, actin dynamics and cyclosis. At present, we can only estimate the amount of energy required, because data from growing pollen tubes are not available. In addition to respiration, we discuss fermentation and mitochondrial localization. We argue that the molecular pathways need to be examined within the physiological context to understand better the mechanisms that control tip growth in pollen tubes.
花粉管通过将储存的细胞淀粉和新同化的糖中的化学能量转移到 ATP 中，从而促进生长。这驱动了无数对于细胞伸长至关重要的过程，直接或通过创建离子梯度来实现。呼吸作用在产生和调节这种能量流动以及植物繁殖的成功中起着核心作用。花粉管很容易在体外生长，已成为研究呼吸作用对植物细胞生长和形态发生的分子、生化和生理水平的重要模型。
在过去的几十年中，花粉管研究越来越关注细胞过程中涉及的分子机制。然而，有效的生长和发育需要一套完整的、整合的细胞过程，所有这些过程都需要源源不断的能量供应。在这里，我们汇集了当前和历史文献中有关花粉管呼吸作用、发酵和线粒体生理学的信息，并在生理背景下评估了最近的分子和遗传研究的意义。
花粉管沿着花柱的快速生长导致了花粉管呼吸作用的高速度进化。百合花粉管的呼吸速率预测每个花粉粒的总能量转换为 40-50 fmol ATP s(-1)。在这个背景下，我们检查了细胞壁合成、渗透调节、肌动蛋白动力学和胞质环流的能量需求。目前，我们只能估计所需的能量，因为没有关于生长花粉管的数据。除了呼吸作用，我们还讨论了发酵和线粒体定位。我们认为，需要在生理背景下检查分子途径，以更好地理解控制花粉管尖端生长的机制。
