Plant Genome III Conference Plant Genome III Conference
Immature somatic embryos of white spruce (Picea glauca) can be stimulated to develop and mature when exposed to exogenous ABA. The development of somatic embryos is characterized by particular morphologies ending with a mature, cotyledonary embryo after about six weeks. Approximately 50% of genotypes have shown a developmental block that prevented the completion of this maturation process. We are therefore interested in research that will contribute to an increased understanding of events associated with ABA stimulated somatic embryo development and maturation. One approach is to study the time-course of ABA stimulated gene activation in the immature somatic embryos of white spruce. We have used a Biolistic transformation method to develop transgenic lines which carry the ABA-inducible heterologous Em-uidA construct in pBMI13Kp. The method used is particularly appropriate for this non-selectable construct, being based on the successive propagation and enrichment of tissue sectors showing a positive reaction to histochemical GUS assay, after incubation with ABA. We describe the transformation process in white spruce and present data on the development of transgenic lines with the ABA-inducible Em promoter.