Regulation of embryo development in culture

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The physiological and molecular events associated to plant embryo development are difficult to study in vivo, due to the inaccessibility of the embryo. The use of somatic embryogenesis, i.e. the generation of embryos in culture from asexual cells, opens new avenues for understanding the mechanisms controlling embryo development, especially during the early stages. The proposed research program utilizes this strategy in canola (Brassica napus) and white spruce (Picea glauca) to investigate two important aspects of embryogenesis: the role played by glutathione metabolism during embryo development in canola microspore-derived embryos and the identification of meristem genes in spruce somatic embryos. Glutathione is a ubiquitous molecule which exists in two forms: a reduced form and an oxidized form. This metabolite is involved in many cellular and developmental processes. Recently we have demonstrated that a switch of the glutathione pool towards its oxidized state improves embryo development and apical meristem formation. As an extension of this work we are interested in identifying genes regulated by glutathione during embryogenesis and in characterizing their function through transformation studies. Such work will be complemented by biochemical studies which will define the role of glutathione in relation to the biosynthesis of purine and pyrimidine nucleotides, which participate in the regulation of plant growth and development. As meristem formation is a key event occurring during embryogenesis, we are also proposing to identify novel ARGONAUTE genes involved in the formation and maintenance of the embryonic apical poles. Transformation studies will be employed to reveal how altered expression of these genes affect the architecture of the meristems. The role of these genes in the regulation of other meristem marker genes will be further investigated using laser capture microdissection techniques. This research will elucidate important mechanisms regulating embryo development and will facilitate the design of novel tissue culture procedures to be used by the Canadian biotechnology industry dedicated to the in vitro propagation of plant species.