Recent advances in forest tree biotechnology

Forest trees produce an important feedstock, wood. Forest tree breeding programs have been traditionally carried out by selecting elite trees to enhance productivity and processability. Recently, however, a biotechnological approach has attracted much attention because it enables efficient and versatile improvement of forest trees. In the last decade, forest tree biotechnology has considerably progressed: genomic sequences of several forest tree species have been decoded, efficient Agrobacterim-mediated genetic transformation and regeneration systems have been established in a number of forest tree species, and many reports have been published on the metabolic engineering of a major wood component, lignin, in forest trees. However, in contrast to the metabolic engineering of lignin, the metabolic engineering of cellulose and hemicelluloses in forest trees awaits further development. The detrimental effects on tree growth are often concomitant with the metabolic engineering of wood components. To mitigate such effects, fine-tuned regulation of transgene expression, and the production of value-added products may be targeted in future forest tree biotechnology.