Transformation of Norway Spruce (Picea abies) by Particle Bombardment

Norway spruce (Picea abies) and Scots pine are the most important European economic forest tree species. Of the 112 million ha of forest in northern and western Europe, Sweden and Finland contribute 44 million ha, of which 40–45% consist of Norway spruce and a similar area consists of Scots pine (FAO 1999). The demand for forest products is expected to increase over the next 50 years, by about 1.7% per year (Fenning and Gershenzon 2002). This increase in demand will have to be met by increased production, for the most part on the same or smaller area. Here, forest tree breeding plays an important role. In Scandinavia, the long rotation cycles of 60–120 years, the minimum of 10–15 years to reach reproductive maturity, and the sporadic seed production provide obstacles to breeding Norway spruce. The traits given particular attention by breeders are: (1) high volume production combined with a growth rhythm that allows timely cold acclimation in the fall and avoidance of damage from late frosts in the spring, (2) quality characters such as straightness, branch thickness and angle, wood density, fibre quality, cellulose content and lignin content and composition, and (3) reduced susceptibility to insects and pathogens, particularly the root-rotting fungi such as Heterobasidion annosum. Shortening the juvenile phase is of special interest for accelerating the breeding programme.