with the next generation of transgenic crops. The second section focuses on policy, beginning with a general discussion of the context in which environmental risk from transgenic crops should be framed and then moving on to specific topics that may arise as policies for the next generation of transgenic crops evolve. The final section is a discussion of some research needs to address future issues.
This section describes anticipated future transgenic crops, including some expected to be commercialized in the next couple of years, others that may reach commercial status on a midterm horizon sometime during the next decade, and others that are mere twinkles of ideas for transgenic crops that will require research breakthroughs before they can reach fruition. As discussed in Chapter 2, it is not possible to characterize the environmental hazards that may be associated with all such crops in advance of knowledge about their phenotypic characteristics and the agricultural ecology of the settings in which they will be grown. However, the second part of this section offers a preliminary discussion of some representative environmental risk issues that may be associated with these new transgenic crops.
The first commercially produced transgenic crops were based on single-gene traits. Among these was the “Flavr-Savr” tomato, which used gene silencing to inhibit the expression of an enzyme involved in fruit ripening (Kramer and Redenbaugh 1994). The Flavr-Savr tomato was not a commercial success, but the technology was effective because the fruit not only had a slow rate of ripening but also was less susceptible to pathogen infection. Other early transgenic products were based on traits influencing agronomic performance (i.e., pathogen, insect, and herbicide resistance). The rapid and broad use by the American farmer of glyphosate-resistant soybeans and Bt-expressing cotton and corn attests to the commercial success of these transgenic crops (James 1998, USDA-NASS 2001).
Based on the successes of these initial transgenic crops, research laboratories throughout the world are now studying a wide variety of traits/ genes that could greatly expand the spectrum of products from such plants. As was true of the first genetically engineered crops, the rate at which new transgenic traits can be expected to appear in the future depends largely on the number of genes encoding them. So traits controlled by single genes, or traits that can be reduced or eliminated by the loss of