Advances in the improvement of forest trees through biotechnology

Tree breeding is a slow process when compared to annual crop breeding becau se of the long generation times typical for trees and the fact that quality traits are only visible at maturity. Nowadays, molecular biology can signi ficantly accelerate tree improvement by identifying genes responsible for d esirable traits and by controlling their expression by gene engineering. Po tential targets for tree improvement are wood quality, tl ce architecture a nd development, sterility, and resistance to pests, diseases and herbicides . The main achievements obtained in these different fields are presented.