Gymnosperm Reproductive Mechanisms

针叶树，如花旗松、云杉和松树是加拿大重要的经济树种。针叶树也是裸子植物中仅存的四个类群之一，从进化的角度来看，这是理解被子植物开花植物起源的关键。这项拟议的研究计划调查从授粉到受精的事件。种子通常由于授粉失败或自花授粉的后果而失败;这种近交胚流产。裸子植物是自由授粉的，不能排除风或昆虫带给胚珠的任何东西。那么，他们如何保护自己呢？它们能选择自己的花粉而不是外来花粉吗？它们有什么机制，这种机制的生化基础是什么？ 花粉-胚珠相互作用包括通过授粉滴捕获花粉，随后花粉萌发并穿透珠心，以花粉管将雄配子递送到卵中结束。我们将从分子的角度来研究这个问题。我们的实验室在授粉滴的蛋白质分析方面积累了深厚的专业知识。我们已经发现，这些酶在繁殖过程中通过杀死微生物来保护胚珠。我们打算调查所有四组裸子植物（针叶树，gnetophytes，苏铁，银杏）的授粉下降，专注于蛋白质（蛋白质组），肽和多肽，糖，磷酸盐化合物，和矿物质。这将通过珠心中基因表达的研究来补充。我们正在寻找与授粉滴分泌物有关的基因，以及那些与花粉生长障碍形成有关的基因，如大孢子壁。最后，我们将研究受精过程中蛋白质组的变化。这些研究是假设驱动的，将吸引三名博士生和一名硕士生。这项工作的影响是实际的，导致更深入地了解针叶树种子果园管理的关键事件。这种影响也是理论上的，因为它可能会改变我们对种子习性进化关键适应的理解。

Conifers such as Douglas-fir, spruce and pines are economically significant species in Canada. Conifers are also one of the four remaining groups of gymnosperms that, from an evolutionary standpoint, are key to the understanding of the origin of flowering plants, the angiosperms. This proposed program of research investigates the events from pollination to fertilization. Seeds often fail because of pollination failure, or because of the consequences of self-pollination; such inbred embryos abort. Gymnosperms are open-pollinated and cannot exclude whatever the wind or insects bring to the ovule. So how do they protect themselves? 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, followed by pollen germination and penetration through the nucellus, ending with the pollen tube's delivery of male gametes into the egg. We will be studying this from a molecular standpoint. Our lab has developed deep expertise in protein analysis of pollination drops. We have discovered that the enzymes protect the ovule during reproduction by killing microbes. We intend to investigate pollination drops in all four groups of gymnosperms (conifers, gnetophytes, cycads, Ginkgo), focusing on proteins (proteome), peptides and polypeptides, sugars, phosphate compounds, and minerals. This will be complemented by an investigation of gene expression in the nucellus. We are searching for genes involved in pollination drop secretions, as well those involved in the formation of barriers to pollen growth, such as megaspore walls. Lastly, we will be investigating the changes in proteome during fertilization. The studies are hypothesis-driven and will engage three PhD students and one Masters student. The impact of this work is practical, leading to deeper understanding of events critical for conifer seed orchard management. The impact is also theoretical, as it is likely alter our understanding of adaptations critical to evolution of the seed habit.