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Environmental Effects of Transgenic Plants: The Scope and Adequacy of Regulation
teristics (Baker 1965) to the crop itself, noting that “soybean does not possess characteristics of plants that are notably successful weeds” (USDA 1997a). (See discussion of Baker’s list of weed characters in the next case study.) Citing evidence provided by DuPont, APHIS said the applicant had not observed any significant changes in such characteristics as seed production, germination, standability, overwintering capacity, or pathogen susceptibility that might affect their potential to become successful weeds.
Potential for Outcrossing to Wild Relatives. APHIS noted that there are no free-living close relatives of cultivated soybean in the continental United States but that there are some wild perennial Glycine species in the Pacific territories. However, soybean cannot naturally hybridize with those species. APHIS acknowledged that soybean naturally hybridizes with G. soja, a weed of northeast Asia (including Japan) but not found in the United States (Kwon et al. 1972, Holm et al. 1979). APHIS also noted that soybean is almost exclusively self-pollinating, so hybrids due to natural outcrossing between the subject lines and wild plants is very rare. Even if outcrossing were to occur, they argue, there would be no significant impact because the high oleic trait confers no selective advantage as it does not appear to contribute to enhanced ecological fitness or weediness characteristic to wild populations.
Potential Impact on Non-target Organisms. APHIS considered the possibility that the modified soybeans might have some deleterious effect on other organisms, including beneficial insects and rare or endangered species. APHIS determined that there would be no significant deleterious impact, citing the nontoxic nature of oleic acid and also that the genes and enzymes responsible for the modified phenotype are naturally present in soybeans. The higher concentration of oleic acid is not known to have toxic properties. Oleic acid is a very common food component (and the primary ingredient of olive oil), so there is substantial history of consumption and literature on nutritional and toxicological aspects.
Observations from field trials revealed no negative effects on nontarget organisms, although specific parameters measured were not provided. APHIS also stated that, since there are no novel proteins in the transgenic soybeans, there is no potential for exposing other organisms to new, potentially harmful proteins. The expressed enzyme is common and well characterized in nature, suggesting no potential for harm to beneficial organisms, and the product, oleic acid, should not result in any harm beyond that caused by a high monounsaturated fat diet. No other potential mechanisms for harm to beneficial organisms were identified.
APHIS discussed the indirect metabolic alterations in the transgenic soybeans, including the presence of a linolenic acid isomer, reduction in