TRANSFORMATION OF WHITE SPRUCE (PICEA-GLAUCA) SOMATIC EMBRYOS BY MICROPROJECTILE BOMBARDMENT

Cotyledonary somatic embryos of white spruce [Picea glauca (Moench) Vo ss] were subjected to microprojectile bombardment with a gene construc t containing a gus=nptII fusion gene. Somatic embryos were used to re- induce the embryogenic tissue after bombardments. Histochemical assay using X-gluc as a substrate showed that all the embryos (100%) were GU S positive 48 h after bombardment. However, only thirteen out of 605 e mbryos (2.2%) remained GUS positive after two months in culture. Three of those thirteen (23%) embryo-derived tissues consistently showed GU S activity for eight months in culture. These putatively transformed e mbryogenic tissues were subjected to Southern blot analysis and the re sults suggested integration of the gus=nptII gene expression cassette in the white spruce genome.