Genetic transformation of conifers utilizing somatic embryogenesis.

Over the last 5 yr, the production of transgenic conifers has been greatly facilitated by the ability to transform somatic embryonal tissues (somatic embryos) via cocultivation with Agrobacterium tumefaciens. This has allowed us to develop protocols for the genetic transformation of several spruce species. Furthermore, these procedures can produce an average of 20 independent transgenic lines (translines) per gram fresh mass of embryonal tissue, providing for the first time the magnitude-of-scale required for implementing large-scale functional genomics studies in conifers. Combined with efficient regeneration of transgenic trees via somatic embryos, the potential for genetic engineering of conifers has been demonstrated by stable reporter gene expression (GUS or GFP) resulting from single insert T-DNA integration events.