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4 Case Studies of APHIS Assessments
Pages 121-166

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From page 121...
... Then four types of transgenic plants that have been deregulated by APHIS are examined. Chapter 5 develops a more general assessment of APHIS oversight and makes recommendations for specific changes.
From page 122...
... The terminator was nopaline synthase polyadenylation sequence from Agrobacterium tumefaciens. The plants also are transgenic for a selectable marker, hygromycin B phosphotransferase from the bacterium Streptomyces hygroscopicus with a rice actin promoter and a 35s polyadenylation sequence from cauliflower mosaic virus (CaMV)
From page 123...
... Environmental Risks Considered by APHIS APHIS does not conduct environmental assessments on notifications, which are assumed to be safe based on meeting the notification criteria and based on using plant-specific performance standards that minimize any chance of plant or gene escape beyond the confines of the field plot. Involvement of Potential Participant Groups There is no public or external scientific involvement for this or any other plant that goes through the notification process.
From page 124...
... The applicants stated that an isolation distance of 1,320 feet would be used to minimize transgene flow by pollen (this is double the 660-foot isolation distance recommended in the APHIS 1997 user's guide)
From page 125...
... There is no reason to assume that absolute isolation should be attained at twice that distance. It is likely there would be some very low level of contamination of any corn grown at or near the 1,320-foot isolation distance from the test plots.
From page 126...
... Virus resistance may be transferred into a crop via conventional breeding methods but only if that resistance already exists in the crop or in a sexually compatible relative. Transgenic virus resistance provides an opportunity for disease resistance in crops whose close relatives are not resistant to the virus in question.
From page 127...
... Both APHIS response documents on the transgenic virus-resistant squashes considered a number of potential risks in some detail. Below is a highly abstracted overview of APHIS's arguments for finding "no significant impact." Environmental Risks Considered by APHIS Disease in the Transgenic Crop and its Progeny Directly Resultingfrom the Transgenes, Their Products, or Added Regulatory Sequences.
From page 128...
... Given that the amount of coat protein in the transgenic squashes is considerably less than that in naturally infected plants, the chances of transcapsidation are lower in transgenic plants than infected ones. Furthermore, APHIS pointed out that even if masked viruses (i.e., viral nucleic acids enrobed with a coat protein of a different virus produced by the transgenes of the plant)
From page 129...
... In both response documents, APHIS concluded that the virus resistance transgenes are unlikely to increase the weediness of yellow crookneck squash (USDA 1994b, 1996~. Impact on Non-target Organisms Other Than Wild Relatives.
From page 130...
... This case study has all three elements that could create such a risktransgenes of a type that could confer a fitness boost in the wild, a sexually compatible wild relative, and the fact that the wild relative has been classified as a weed. If the crop mates with the wild relatives introducing virus resistance into wild populations and if the primary factor limiting the aggressiveness of wild populations is disease caused by the same viruses, introgression of the transgenes could result in increased weediness of the wild relatives.
From page 131...
... APHIS concludes that natural hybridization will move the virus resistance genes from the transgenic crop to the wild populations (USDA 1994b, 1996~. FLCP is an agricultural weed in cotton and soybean fields.
From page 132...
... Some comments suggested experimental approaches for measuring whether virus resistance would confer a fitness benefit to the wild plants. Two types of experiments were proposed: 1.
From page 133...
... The APHIS statement above that "the selective pressure to maintain the virus resistance genes" and others in the documents belies an assumption that crop alleles are maintained in natural populations only when they are beneficial. Population genetics theory has demonstrated that even very low levels of gene flow (two successful pollinations per generation)
From page 134...
... However, the APHIS expectation that only beneficial alleles will be maintained in natural populations under gene flow from crops reflects inadequate expertise in population genetics at the time the squash documents were prepared. APHIS may well be correct that virus resistance would not result in increased weediness of FLCP.
From page 135...
... announcing an environmental assessment (EA) and preliminary finding of no significant impact (FONSI)
From page 136...
... acid, the major constituent of olive oil. Each plant species produces enzymes to act on the fatty acids to synthesize a mixture of fatty acids characteristic of the seed oil for that species.
From page 137...
... This enzyme is encoded by a gene called Gm fad 2-1, which catalyses the biochemical reaction converting oleic acid to linoleic acid. DuPont's strategy was to develop transgenic soybean lines in which the inserted soybean gene interferes with the normal activity of that enzyme through cosuppression, resulting in a buildup of oleic acid and a reduction in linoleic and other polyunsaturated fatty acids.
From page 138...
... But the activity of the Gm fad 2-1 at locus B caused accumulation of the active enzyme, resulting in the reduction of oleic acid to less than 4% of seed oil. Because reduced oleic acid content was undesirable, conventional plant-breeding methods were used to eliminate the chromosomecarrying locus B (consisting of both the active Gm fad 2-1 transgene and the dapA-containing plasmid)
From page 139...
... APHIS concluded that introduction of the vector DNA does not present a plant pest risk in the subject soybean lines because there are no pathogenic DNA sequences present, plus the likelihood of nonsexual transmission of DNA to other organisms is exceedingly small and, even in that eventuality, would not constitute a plant pest hazard. Finally, even though the DNA constructs did use portions derived from known plant pathogens (Agrobacterium tumefaciens and CaMV)
From page 140...
... 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.
From page 141...
... The linoleic acid isomer is also found in other common foods, including partially hydrogenated vegetable oils and human breast milk, so it is unlikely to be harmful in the transgenic soybeans. Soybean naturally produces antinutritional components, notably trypsin inhibitors, physic acid, and oligosaccharides.
From page 142...
... If polyunsaturated fatty acids help the seed survive cold winters, perhaps the transgenic soybeans, with such a deficit of polyunsaturates, would have reduced winter survival capacity. The data required to address this question might have been considered and investigated but were not included in the report.
From page 143...
... There is no indication that the risks associated with these transgenic soybean lines differ in any material way from those of the same species with similar but non-transgenic based attributes. High oleic acid oil soybean varieties, regardless of how the varieties were derived, appear to present similar degrees of hazard.
From page 144...
... field corn acreage was sprayed for ECB before adoption of Bt corn (Gianessi and Carpenter 1999~. Genetically based pest resistance in corn was developed through the use of conventional breeding methods utilizing mechanical, chemicalrepellent, or antibiotic properties of the corn plant.
From page 145...
... The genetic sequence encodes production of a toxic protein so that plant tissues become lethal to target caterpillar pests feeding on those tissues. At least three major opportunities are afforded by transgenic insect resistance traits in crops: (1)
From page 146...
... Environmental Risks Considered by APHIS Disease Resulting Directlyfrom the Transgenes, Their Products or Added Regulatory Sequences. For Event 176, two promoter sequences were used to allow high levels of CrylAb protein expression in both green tissue and pollen, which in combination were expected to be most effective in controlling ECB.
From page 147...
... APHIS concluded that since insect resistance was not among the weedy characteristics listed by Baker, that trait would not likely contribute to weediness in transgenic Bt corn. The herbicide tolerance trait of Event 176 was not perceived as one that could reverse the plant's nonweed status, primarily because glufosinate had not yet been registered for use in corn.
From page 148...
... The environmental assessment should then explain the reasoning for adhering to some but not other authorities. Second, the herbicide tolerance trait in Event 176 corn was considered not to pose a hazard in terms of "weedier" free-living relatives because glufosinate had not yet been registered for use in corn and exerts no selection pressure for this trait in nature (USDA 1995~.
From page 149...
... For example, the determination for CBH-351 mentioned that increased weediness of corn due to an insect resistance trait has not been reported, as far as APHIS is aware. The committee agrees that if a phenomenon is dramatic and occurs over a short time period, it is likely to be noticed and even reported.
From page 150...
... The analysis of Event 176 for impacts on corn relatives was not conceptually different from the analysis of corn's weediness. No other wild relatives, in the United States or abroad, were mentioned in this section of the determination despite the fact that sexual transfer of beneficial alleles from a transgenic crop to a wild relative that might result in a more difficult weed had been a widely discussed risk associated with transgenic crops prior to that time (e.g., Colwell et al.
From page 151...
... Whereas the absence of selection pressure by herbicides was mentioned for the herbicide tolerance trait and weediness, no clear analysis of release mechanisms for wild relatives was provided by APHIS with respect to herbivore selection pressure. APHIS's view of whether introgression of the transgene into wild relatives could occur seems to have changed from impossible for the first Bt corn determination to being unlikely in the United States and likely in Mesoamerica for the most recent determination.
From page 152...
... When considering whether transfer of a Lepidopteran resistance trait could allow an ecological release (i.e., an increase in population size, density, or range) of any wild relatives of corn, two further questions arise.
From page 153...
... Whether or not conventionally bred insect resistance traits in corn and the Bt-based resistance trait inserted in CBH-351 corn are similar enough to make conclusions about the selective pressure of the Bt traits on feral progeny or hybrids with wild relatives is unknown. The genetic novelty of Bt toxins and herbicide resistance is likely to be outside the range of natural variation found in populations of wild relatives, whereas some of the traits responsible for causing Lepidopteran resistance in conventional corn hybrids may correspond to traits already present in populations of corn's wild relatives (e.g., tough stalks, low protein content, high DIMBOA content)
From page 154...
... Bobwhite quail showed no adverse effects on feed consumption, body weight, or mortality when fed corn protein powder from Bt or isogenic non-Bt hybrids. Indirect effects of Bt corn on quail through its changes in its food supply were considered by APHIS to be negligible if the effect of Bt corn is restricted to the European corn borer (however, it is known that Btk affects many Lepidoptera)
From page 155...
... . They noted, for example, that aphids were not an appropriate test prey for determining indirect effects of Bt proteins on natural enemies since the aphids may not ingest Bt proteins.
From page 156...
... APHIS considered evolution of pest resistance to Cry proteins for Event 176. These proteins are similar to those used for ECB control in commercially available crystalline powder formations.
From page 157...
... Environmental Risks Not Considered by APHIS APHIS did not directly consider whether transgenic corn would have a negative impact on corn's wild relatives in the United States or elsewhere, either in terms of changes in their genetic diversity or in terms of posing an impact that might lead to their extinction. This is likely due to the conclusions that hybrids with Zea or Tripsacum would rarely occur, especially in the United States.
From page 158...
... Transgenic cultivars with herbicide tolerance and/or insect resistance were planted on over 40 million hectares in 2000 (James 2000) , making
From page 159...
... Increasingly, cotton cultivars are being produced that have both herbicide tolerance and insect resistance. In 2000, one-third of all transgenic cotton in the United States had both traits (USDA-NASS 2001~.
From page 160...
... Environmental Risks Considered by APHIS in Its Environmental Assessments and Determination Documents Disease in the Transgenic Crop and Its Progeny Resultingfrom the Transgenes. Because the herbicide tolerance and Bt genes were inserted using Agrobacterium tumefaciens, and because a cauliflower mosaic virus 35S promoter and a chimeric 35S promoter were part of the inserted DNA, APHIS examined the potential for risk from these sequences that came from plant pest species.
From page 161...
... The environmental assessment indicated that the EPA's active resistance management program should delay the onset of resistance. APHIS also concluded that if resistance to Bt does evolve in insect pests, the ability to control the insects will not be reduced because conventional insecticides will still be available.
From page 163...
... Impacts of Commercialization of Transgenic Cotton on Environments Outside the United States. Other APHIS environmental assessments discuss concerns about the impact of a transgenic crop approved for use in the United States being planted in other countries.
From page 164...
... When two traits are combined in a single cultivar and it is impossible to purchase cultivars with only one of the two traits, farmers are forced to buy a cultivar with both traits even if they need only one for their farming operation. In the case of the stacking of herbicide tolerance and Bt toxin production, a farmer who needs herbicide tolerance may end up planting cotton with the Bt trait, even if the densities of the Bt target pests on the farm do not warrant control with the Bt trait.
From page 165...
... If APHIS reviews transgenic plants with weedy cross-compatible relatives in the United States, such as canola, with stacked herbicide tolerance and insecticidal genes, it would definitely need to consider this interaction. Public Involvement The APHIS environmental assessment indicated that the agency received no responses to its Federal Register announcement of this petition
From page 166...
... CONCLUSION This chapter has reviewed case studies of the three primary APHIS regulatory pathways for field release of transgenic organisms as well as a representative sampling of the vast array of transgenic species, phenotypes, and molecular mechanisms designed to obtain those phenotypes. In many cases the committee simply reports, without much comment, how and with what information APHIS made a specific decision.


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