Plant Biotechnology in Forestry

Forests are both economically and environmentally important. The demand for wood products, such as timber for construction, paper, pulp and energy, is increasing and expanded plantation forestry will be required to meet the global demand. The time lines for tree breeding have made progress in improving forest productivity slow. Now, the full range of biotechnological technologies is being applied to tree improvement. These include clonal micropropagation of superior trees, hybridisation, molecular markers and marker-assisted selection and transformation.
A range of tree species has been transformed using both Agro- bacterium and particle bombardment approaches:poplar, European larch, hybrid larch, Norway spruce, Scots pine, white spruce, black spruce, eastern larch, radiata pine, Tasmanian bluegum and a range of Eucalyptus species. The targets for tree improvement involve improved growth rate, wood characteristics, pulp quality, pest and disease resistance and tolerance to abiotic stresses.
A major target is to engineer reduced lignin content, since lignin represents about 25% of the wood biomass and lignins reduce the efficiency of pulp and paper production. High energy usage and production of chemical pollutants also result from delignification processes. This has been achieved by down-regulation of key enzymes in the lignin biosynthetic pathway [e.g. cinnamyl alcohol dehydrogenase (CAD); O-methyl transferase (OMT)].
Transgenic trees have also been generated with modified form, quality and performance using auxin biosynthetic genes, rol c genes and peroxidase, and also with herbicide resistance and Bt insect resistance.
Environmental considerations are particularly important for growth of transgenic trees. In order to reduce gene flow via pollen to native species, engineered sterility of transgenics is desirable.