The two main commercial developments which have so far arisen from the genetic modification of plants are of limited relevance to forestry, since one has involved conferring pest resistance by the insertion of a gene from Bacillus thuringiensis, and the other, resistance to the herbicide glyphosphate by the insertion of a resistance gene. However, neither herbicides nor insecticides are widely used in forestry: insecticides are usually restricted to occasional surface-limited treatments, and herbicides are applied only during a short initial period in a tree's life. In Canada, less that 5 percent of the pesticides sold are used in the forestry sector (Carrow 1995).
However, despite the fact that the first generation of GM products was not very relevant to forestry, there are numerous ways in which the technology could be useful to the sector, and many research groups are actively developing and implementing methods for the genetic modification of trees. Protocols are being developed for gene delivery to various tree tissues, including flower parts and pollen. This will allow researchers to bypass the long life-cycle of trees and quickly verify patterns of expression of the introduced genes in mature tissues. In this way, traits based on single genes (e.g. pest tolerance) can be rapidly transferred to superior genotypes. Future goals include the introduction of genes for flower sterility, e.g. into conifer species to eliminate potential problems of invasiveness and to minimize gene flow to related trees (Canadian Forest Service 2002). Thus, there seems to be considerable potential for developing new genotypes of forestry trees with very useful biological traits. Genetically modified biological control agents, especially pathogens such as viruses and fungi, are also being considered (e.g. Canadian Forest Service 1997).
However, as yet, there are no generally accepted protocols for assessing the risks associated with these new varieties. Assessing risks in long-term crops such as forestry trees is difficult, and the large-scale uptake of this technology is likely to be slow unless reliable protocols can be developed and the risks found to be acceptable.
Some strong opinions have been expressed against the use of genetically modified trees in forestry, e.g. by the Forest Stewardship Council (Case Study 17). In May 1999, the World Wide Fund for Nature (WWF) formulated a position statement on GMOs, which called for (i) a moratorium on the use or release of GMOs until ecological interactions are fully researched; (ii) transparent, comprehensive environmental impact assessments of planned releases; and (iii) properly regulated monitoring and control of gene technology.
Developing countries are watching developments in this area with keen interest, and are caught between the desire to gain potential benefits from this new technology and concerns over possible side-effects and fears that their farmer-generated germplasm may be used by international seed companies without adequate recompense. Many developing countries are now actively seeking objective external sources of advice on these issues.
