Gymnosperm reproduction

当花粉使植物胚珠受精时，就形成了种子。种子在人类历史上很重要：我们消耗或已经消耗的所有卡路里中有三分之二来自胚乳，胚乳是一种来自被子植物胚囊或雌配子体的种子组织。裸子植物，如针叶树，也是种子植物，尽管在某些繁殖方面更原始。尽管我们通常不吃针叶树种子，但它在加拿大具有至关重要的经济重要性，因为我们从我们的道格拉斯冷杉、云杉和松林中获得了巨大的财富。我们了解如何根据树的形状和生长速度、对病虫害的抵抗力以及木材质量来培育树木。然而，我们最近才开始了解胚珠和种子发育过程中的机制。了解授粉、受精和种子发育的基本过程将为我们提供知识，以便在生产丰富的重新造林种子时创造更高的效率。种子可能会因为授粉失败或自花授粉的后果而无法发育；这样的近亲繁殖胚胎就会死亡。针叶树是开放授粉的，不能排除风给胚珠带来的任何东西。它们能选择自己的花粉而不是外来的花粉吗？它们有什么机制，这种机制的生化基础是什么？花粉-胚珠的相互作用包括通过从胚珠中渗出的授粉滴捕获花粉，随后花粉萌发并穿过珠心，最终花粉管将雄配子传递到卵子中。这项拟议的研究计划将调查从授粉到受精的过程。我们将从分子的角度研究这一点。我的学生将从事蛋白质分析。例如，授粉液滴似乎是一种特定物种的萌发媒介，比起来自其他物种的花粉，它更有利于自己的花粉。柏树和雪松的授粉液滴在授粉后很快就会缩回，这意味着一种活跃的机制。我们将解开这一机制。我们还将研究各种具有进化意义的裸子植物受精、胚珠发育和卵子成熟过程中蛋白质组的变化。这些研究是假设驱动的，将涉及两名博士生。这项工作的影响是实际的，有助于更深入地了解对有效管理生殖至关重要的事件。我的工作也可能有助于理解对种子进化至关重要的适应。

When pollen fertilizes a plant ovule, seed is formed. Seed is important in the history of humanity: two-thirds of all calories that we consume or have consumed are from endosperm, which is a seed tissue derived from the angiosperm embryo-sac, or female gametophyte. Gymnosperms, such as conifers, are also seed plants, albeit more primitive in some of their reproductive aspects. Even though we don't commonly eat conifer seed, it is of critical economic importance in Canada, because we derive great wealth from our forests of Douglas-fir, spruce and pines. We understand how to breed trees for form and growth rate, resistance to pests and disease, and for wood quality. However, we are only recently beginning to understand mechanisms that occur during ovule and seed development. Understanding the underlying process of pollination, fertilization and seed development will provide us with the knowledge to create greater efficiencies when it comes to producing abundant seed for reforestation. Seeds can fail to develop because of pollination failure, or because of the consequences of self-pollination; such inbred embryos die. Conifers are open-pollinated and cannot exclude whatever the wind bring to the ovule. Can they select their own pollen over foreign pollen? What mechanisms do they have, and what is the biochemical basis for the mechanism? Pollen-ovule interactions include pollen capture by a pollination drop exuded from the ovule, followed by pollen germination and penetration through the nucellus, ending with the pollen tube's delivery of male gametes into the egg. This proposed program of research will investigate the events from pollination to fertilization. We will study this from a molecular standpoint. My students will be working on protein analysis. Pollination drops, for example, appear to be a sort of species-specific germination media, favouring their own pollen over pollen from other species. Pollination drops of cypress and cedar species retract very quickly after pollination, implying an active mechanism. We will unravel this mechanism. We will also be investigating the changes in proteome during fertilization, ovule development and egg maturation of a variety of evolutionarily significant gymnosperms. The studies are hypothesis-driven and will engage two PhD students. The impact of this work is practical, leading to deeper understanding of events critical for effective management of reproduction. My work is also likely to contribute to understanding of adaptations critical to the evolution of seeds.