Somatic Embryogenesis as a tool for forest tree improvement: a case- study in Eucalyptus globulus

Background Somatic embryogenesis (SE) technology is expected to play a significant role in future forest tree improvement programs. Methods for efficient SE propagation in softwood species based on bioreactors are underway [1]. Furthermore, genetic transformation through SE is also the most promising approach to generate and propagate elite recalcitrant genotypes of forest trees [2], or clonal propagation of selected endangered high-value forest trees [3,4]. Somatic embryogenesis induction was first reported for the genus Eucalyptus in 1980. Mass production of SE plants however remains difficult although procedures designed for plant regeneration have been reported for E. citriodora, E. grandis, E. tereticornis[5]. Recent data on E. globulus are promising and show the potential of this technology for application in clonal forestry [6,7]. A service platform for routine transformation of forest trees has been established at the Berzelii Center at Umeå Plant Science Centre using Norway spruce as the primary model species for gene function analyses. Other target species for future studies include hardwood species such as Poplar and Eucalyptus. We present here a brief summary of a case study for introduction of a recalcitrant forest species to the platform as demonstrated by the establishment of the SE technology for E. globulus following protocol previously established in Portugal [6,7] and preliminary results aiming to improve the induction of SE.