Gymnosperm reproduction

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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.