I am writing to address the conclusion raised by two contributors, who argued that due to the complexity of the nature of trees and their adaptation to the environment, it was not possible to make risk assessment of genetically modified trees, and therefore we should not try, or worse, yet, not be allowed to try. This issue was addressed nearly two decades ago, following discussions among government agencies, particularly, EPA, and USDA, on the prospects for regulating genetically modified organisms in agriculture and in the environment (see Bio/Technology 8, 1229 (1990) Codifying Common Sense, Douglas McCormick). In this article, several common sense principles were proposed for regulation. They still apply today to issues regarding genetically modified trees.
First, the article reiterated the argument, that the product, not the process should be regulated. This fundamental principle is still not widely accepted today, in spite of the strength of the science supporting it. Instead, the process is widely regulated, and justified by the invocation of the precautionary principle.
The article “Codifying Common Sense’ sets out that regulation should begin with criteria based on what organisms and genetic modifications are considered safe now. We do not regulate traditional tree breeding, clonal forestry, tree hybridization, any cell and tissue culture procedures, trees derived by somaclonal variation, mutation breeding, or breeding or deployment of any exotic tree germplasm, once it passes quarantine and is in this country. Much is not known about the genetics of tree species and populations of forest trees, nonetheless, these introductions, selections and manipulations are unregulated.
Secondly, the nature of the modification should be considered. What is known about the mechanism of introduction, the genes themselves, the vector, the insertion site, and the expression of the construct. These issues are quite specific, and have in some cases, there is a high level of knowledge and confidence in what can be expected in a genetically modified plant. The risk can be evaluated in the context of the level of knowledge about natural mobile elements, producing insertions, transpositions, footprints, and altered gene regulation, widely throughout the organism. Plant genomes are dynamic and modification of sequence and position of genes and elements are natural forces for evolution and adaptation.
Third, what is the nature of the anticipated modification to the organism, and what would be the expected change to its growth, development, metabolism or adaptation. Such evaluations would vary in complexity, but some could be simply classified, as having an advantage under a particular condition, a disadvantage under such conditions, and in many cases, it could be argued that the change could be essentially neutral. Again, the baseline should be the relative effect compared to genes in natural populations, where many alleles are segregating, with advantageous, or deleterious effects, all subject to natural selection.
Finally, risk is to be balanced against the degree of containment. If containment can be applied, the risk that can be accepted should be higher than a case where, no containment is possible.
For forests, it must be remembered that many forests have dynamic histories. The lifetime of any population may have been short, and the history of human and natural intervention in forests has had dramatic consequences within relatively few tree generations. Particularly in North America, the temperate forests in the eastern USA have changed dramatically several times since the decline of the Wisconsin glaciation, due to competition, adaptation, the extent of fire, agriculture, pests and pathogens, and additional anthropogenic impacts on the land.
Yes, there is much we do not know about trees and forests. However, that does not preclude the application of common sense, when it comes to regulations that could apply to genetically modified trees.
Ron Sederoff
North Carolina State University (NCSU)
Ron_Sederoff@ncsu.edu