Reverse genetic approaches are the only realistic alternative for the analysis of gene functions in trees because of their long generation time and obligatory out-crossing of most trees. UPSC scientists were among the first in the world to be able to create transgenic trees.
All initial work was done with a fast-growing and relatively easily transformable hybrid aspen (Populus tremula x tremuloides) clone originating from the Czech Republic called “T89”. This is still the main tree species used in the transformation facility, but the numbers of different tree species that are routinely transformed have now grown to include elite varieties of hybrid aspen, Populus trichocarpa, Populus alba, Populus tremula and also Betula pendula (silver birch).
The method used is Agrobacterium-mediated plant transformation of stem segments, petioles or leaf explants and the facility is today growing more than 15 000 transgenic trees, representing more than 5000 different lines, probably making this the largest tree transformation facility in the world. The transformation facility currently employs five fulltime persons and is servicing all the research groups at UPSC and collaborators at both Umeå University and the Swedish University of Agricultural Sciences. Any group requiring transformed trees simply needs to provide the Agrobacterium strain carrying the genetic construct they want to analyze. After 8-10 months the trees are ready to be transferred to the greenhouse for analysis.