Swanson Robert, Edlund Anna F, Preuss Daphne
Department of Molecular Genetics and Cell Biology, The University of Chicago, Illinois 60637, USA.
Annu Rev Genet. 2004;38:793-818. doi: 10.1146/annurev.genet.38.072902.092356.
For pollination to succeed, pollen must carry sperm through a variety of different floral tissues to access the ovules within the pistil. The pistil provides everything the pollen requires for success in this endeavor including distinct guidance cues and essential nutrients that allow the pollen tube to traverse enormous distances along a complex path to the unfertilized ovule. Although the pistil is a great facilitator of pollen function, it can also be viewed as an elaborate barrier that shields ovules from access from inappropriate pollen, such as pollen from other species. Each discrete step taken by pollen tubes en route to the ovules is a potential barrier point to ovule access and waste by inappropriate mates. In this review, we survey the current molecular understanding of how pollination proceeds, and ask to what extent is each step important for mate discrimination. As this field progresses, this synthesis of functional biology and evolutionary studies will provide insight into the molecular basis of the species barriers that maintain the enormous diversity seen in flowering plants.
为了使授粉成功，花粉必须携带精子穿过各种不同的花组织，以接触雌蕊内的胚珠。雌蕊为花粉在此过程中成功所需的一切提供了条件，包括独特的引导线索和必需的营养物质，这些营养物质使花粉管能够沿着复杂的路径穿越巨大的距离到达未受精的胚珠。虽然雌蕊极大地促进了花粉的功能，但它也可以被视为一个精心构建的屏障，保护胚珠不被不适当的花粉接触，比如来自其他物种的花粉。花粉管在通往胚珠的途中所采取的每一个离散步骤，都是防止不适当的配偶接触胚珠和造成浪费的潜在障碍点。在这篇综述中，我们概述了目前对授粉过程的分子理解，并探讨了每个步骤对配偶识别的重要程度。随着该领域的发展，这种功能生物学与进化研究的综合将为维持开花植物中巨大多样性的物种屏障的分子基础提供见解。
