The release of Bt cotton varieties genetically modified for increased tolerance to major cotton insect pests provided impetus for the reestablishment of a cotton industry in northern Australia. However, this stimulated concern that the addition of the gene might facilitate an increase in the potential for weediness of genetically modified cultivars in noncropping habitats. Bt and conventional cottonseeds were planted in 12 sites in northern Australia to test the hypothesis that there would be no increase in the ability of Bt cotton vs. conventional cotton to establish weedy, or invasive populations, defined as population growth over time greater than one, irrespective of location, habitat, seed type, or population density. Invasiveness was a factor of germination, survival, and recruitment. We examined whether the addition of the Bt gene would increase fitness of these parameters, and associated invasiveness. An irrigation drain was considered a high-risk habitat for cotton establishment, so an additional site was sown at that habitat to provide supplementary data to the original 12 sites. Location and habitat were the dominant factors influencing germination, survival, fecundity, and invasiveness. Bt and non-Bt cottonseeds did not differ in their ability to germinate, establish, and survive. After 2 yr, cotton plant survival was very low, and only 3 of 13 sites established fecund cotton populations. Measurements continued for an additional 2 yr at these sites. There was no increase in values for invasiveness for the Bt genotype treatments at any location or habitat after 2 yr or at two selected habitats after > 4 yr, demonstrating that the addition of the Bt gene will not confer increased fitness for weediness. Mean invasiveness values for each habitat, irrespective of genotype, were less than one, indicating that neither conventional nor Bt cotton would establish invasive cotton populations in northern Australian habitats.

Jointed goatgrass is an exotic species introduced into the western United States from Eurasia. The weed is an agricultural pest infesting winter wheat fields and causing economic loss. Common ancestry between the two species enables interspecific hybridization, thus providing a mechanism for gene flow to occur. This can facilitate the accumulation of novel genes, which could increase the wild species' competitiveness with wheat and its ability to invade novel habitats. Interest in the development of transgenic wheat cultivars has increased the concern for interspecific gene flow. Gene introgression requires recurrent backcrossing to the weedy species after the initial hybridization event. Field experiments were conducted at two locations in Colorado in 2007–2008 and 2008–2009, with jointed goatgrass acting as the sole source of viable pollen for fertilization of transplanted hybrid plants. Backcrossing rates were determined by conducting germination studies on spikes collected from a total of 206 hybrid plants. Pollination by jointed goatgrass led to the production of 463 BC1 plants from seed produced on these 206 hybrid plants. Ninety-five percent confidence intervals estimate the rate of backcrossing at 0.028 to 0.306% and 0.077 to 0.604%, with medians of 0.062 and 0.152%, respectively, at the two locations. The results demonstrate that backcrossing to jointed goatgrass can occur, despite low rates of hybrid fertility. Subsequent backcrossing would make it likely that a wheat gene conferring a selective advantage will introgress into the weedy population. For the U.S. Great Plains, it is possible that transgenic wheat cultivars will be released in the future and determining proper management of these cultivars is necessary to minimize hybridization and advantageous gene introgression into weedy relatives.

Corn containing high levels of available phosphorus (HAP) allows poultry to use more of the phosphorus they consume and could potentially reduce contamination of water from run-off. This study uses a conjoint analysis survey of Delmarva corn growers to model adoption of hypothetical HAP varieties over a three-year period. An optimal variety has a low technology fee and yield drag and a high harvest premium. Adoption of HAP corn increases during the period although growers’ tolerance of technology fees and yield drags diminishes over time. Adoption is further affected by farm size, farmer age, and the portion of income from corn.

Typical supermarket chickens are produced with novel or controversial attributes. This continues despite contrasting growth in consumer interest in organic and natural foods. This study surveyed Delaware consumers' likelihood to purchase chicken given different attributes: free range, given antibiotics, irradiated, fed genetically modified (GM) feed, GM chicken, and price. Examining conjoint analysis data with a heteroskedastic two-limit tobit model, GM chicken and other novel attributes were found to lower purchase likelihood significantly. Understanding these results should help the industry meet consumer preferences while aiding its continued expansion to benefit workers and growers across the South.

One source of phosphorous pollution in areas of high chicken production isrunoff from fields using fertilizer from these operations. A potentialsolution is to feed chicken high available phosphorus (HAP) corn, reducingphosphorus in manure. This study examined consumer purchase likelihood ofchickens fed HAP, created traditionally or through genetic modification, andother genetically modified (GM) corn including Bt and Roundup-ready. Surveyresults from the Delmarva Peninsula found considerable interest in non-GMHAP corn, although GM HAP corn was not typically viewed as more acceptablethan other GM varieties. Overall, the marketplace appears open to productsgeared toward environmental benefits.

Testing for the unintended or adventitious presence (AP) of genetically modified (GM) events in seed lots is a common practice to comply with regulatory requirements and good stewardship practices. A subsample of a seed lot is typically tested for AP levels, and then statistical methods are used to estimate the upper level of AP in the remainder of the lot with a given level of confidence. For large seed lots, a binomial distribution is typically assumed, but for seed lots where the tested sample is a substantial proportion of the overall seed lot, a hypergeometric distribution is typically assumed. Due to the destructive nature of AP seed testing, we suggest that this latter method may overestimate confidence of low AP in the remaining seed.

Twenty crossbred lactating multiparous cows were used in a 28-day study to compare dry matter intake (DMI), milk yield, milk composition and Bacillus thuringiensis (Bt) protein concentrations in plasma when fed diets containing Bollgard II® cottonseed (BGII) or a control non-genetically modified isogenic cottonseed (CON). Bollgard II cottonseed contains the Cry1Ac and Cry2Ab insecticidal proteins that protect cotton plants from feeding damage caused by certain lepidopteran insects. Cows were assigned randomly to the BGII or CON treatments after a 2-week adjustment period. Cows consumed a concentrate containing 40% crushed cottonseed according to milk yield and green maize forage ad libitum. All cows received the same diet but with different crushed cottonseed sources. Cottonseed was included to provide approximately 2.9 kg per cow daily (dry matter basis). The ingredient composition of the concentrate was 40% crushed cottonseed, 15% groundnut cake, 20% corn, 22% wheat bran, 1% salt and 2% mineral mixture. Milk and blood plasma were analyzed for Cry1Ac and Cry2Ab proteins. DMI, BW, milk yield and milk components did not differ between cows on the BGII and CON treatments. Although milk yield and milk fat percentage were not affected by treatment, 4% fat-corrected milk (FCM) production and FCM/kg DMI for cows on the BGII treatment (14.0 kg/cow per day, 1.12 kg/kg) were significantly improved compared with cows on the CON treatment (12.1 kg/cow per day, 0.97 kg/kg). Gossypol contents in BGII cottonseed and conventional cottonseed were similar. Cry1Ac and Cry2Ab2 proteins in Bollgard II cottonseed were 5.53 and 150.8 μg/g, respectively, and were not detected in the milk or plasma samples. The findings suggested that Bollgard II cottonseed can replace conventional cottonseed in dairy cattle diets with no adverse effects on performance and milk composition.

Transgenic fish in development for aquaculture could escape from farms and interbreed with wild relatives in the nearby environment. Predicting whether escapes would result in transgene introgression is a major challenge in assessing environmental risks of transgenic fish. Previous studies have simulated gene flow from transgenic fish using mathematical modeling of fitness traits to predict the relative selective value of transgenic genotypes. Here, we present the first study of gene flow over the full life cycle in openly-breeding populations of transgenic animals, along with measurement of fitness traits. We conducted two invasion experiments in which we released two lines of growth-enhanced transgenic fish (T67 and T400), Japanese medaka (Oryzias latipes), into populations of wild-type (W) medaka in structured mesocosms. After several generations, the frequency of transgenic fish varied across replicates in the first invasion experiment (6 months), but the frequency of transgenic fish decreased in the second experiment (19 months). We also measured selected fitness traits in transgenic and wild-type medaka because these traits could be used to predict the relative selective value of a genotype. We found that: T400 males were more fertile than W males; offspring of W females lived longer than those with transgenic mothers; and W and T67 females reached sexual maturity sooner than T400 females. In contrast with other research that reported larger transgenic males had a mating advantage, we found that W males obtained more matings with females than T males; genetic background effects may account for our differing results as we compared W and T fish derived from different strains. The decreasing frequency of transgenic fish in the second invasion experiment suggests that transgenic fish had a selective disadvantage in the experimental environment. Our finding of transgenic advantage of some fitness traits and wild-type advantage in others is consistent with our invasion experiment results.

Many varieties of transgenic rice are under development in countries where wild and weedy relatives co-occur with the crop. To evaluate possible risks associated with pollen-mediated transgene dispersal, we conducted a two-year survey in Vietnam to examine overlapping flowering periods of rice (Oryza sativa L.), weedy rice (O. sativa), and wild rice (O. rufipogon Griff.), all of which are inter-fertile. We surveyed populations in two regions of the Mekong Delta, northern and southern, and at three sites in each of three habitats per region: fresh water, saline water, and acid sulfate soil. Weedy rice frequently flowered simultaneously with neighboring cultivated rice plants. Flowering was more seasonal in wild rice and often peaked in November and December. Peak flowering times of wild rice overlapped with adjacent rice fields at all of the saline sites and half of the acid sulfate sites. The longer flowering season of wild rice ensured that crop-to-wild gene flow was possible in fresh water habitats as well. Our second objective was to determine whether wild and weedy rice populations are exposed to pests that could be targeted by future transgenes, which may then provide fitness benefits. These populations shared many pathogen and insect herbivore species with cultivated rice (leaffolder, locust, cricket, planthoppers, rice bug, stem borer, sheath blight, blast, bacterial leaf blight, and brown spot). Damage by leaffolders and locusts was the most frequently observed insect feeding damage on all three rice types. Indicator species analysis revealed that most of the insect herbivores were associated with particular habitats, demonstrating the importance of broad geographic sampling for transgenic rice risk assessment. These survey data and the strong likelihood of gene flow from cultivated rice suggest that further studies are needed to examine the effects of transgenic traits such as resistance to pests on the abundance of wild and weedy rice.

Out-crossing between genetically modified herbicide-tolerant (GMHT) and non-GM rape cultivars was studied using GMHT source field plots of approximately 0.8 ha. Levels of cross-pollination between adjacent fully fertile rape varieties declined rapidly with increasing distance from the interface between plots. A varietal association with low levels of male sterility showed higher levels of out-crossing than other varieties. Out-crossing data were used to compare negative exponential and inverse power-law models for their fit to describe the observed relationship between cross-pollination and distance from source. Results showed that the inverse power-law model provided a better fit of the data.

Guidelines to ensure the efficient coexistence of genetically modified (GM) and conventional crops are currently being considered across the European Union. The purpose of this strategy is to describe the measures a farmer must adopt to minimize the admixture of GM and non-GM crops. Minimizing pollen / seed-mediated gene flow between GM and non-GM crops is central to successful coexistence. However no system is currently available to permit the numeric quantification of a crop’s propensity for pollen/seed-mediated gene flow. The provision of such a system could permit a background level of gene flow, specific for a particular conventional crop, to be calculated. Here we present a gene flow index model implemented using the principal arable crops in Ireland as a model dataset. The objective of this research was to establish a baseline gene flow data set for Ireland’s primary conventional crops through the provision of a simple numerical index. This Gene Flow Index (GFI) incorporates four strands of crop-mediated gene flow (crop pollen-to-crop, crop pollen-to-wild, crop seed-to-volunteer and crop seed-to-feral) into a format that permits the calculation of a crop’s gene flow potential. Responsive to regional parameters, we have applied the model to sugar beet, oilseed rape, potato, ryegrass, maize, wheat and barley. We propose that the attained indices will highlight those crops that require additional measures in order to minimize gene flow in accordance with anticipated coexistence guidelines.

The use of transgenic crops as feeds for ruminant animals has prompted study of the possible uptake of transgene fragments by ruminal micro-organisms and/or intestinal absorption of fragments surviving passage through the rumen. The persistence in buffered ruminal contents of seven different recombinant DNA fragments from GM rapeseed expressing the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) transgene was tracked using PCR. Parental and transgenic (i.e. glyphosphate-tolerant; Roundup Ready®, Monsanto Company, St Louis, MO, USA) rapeseed were incubated for 0, 2, 4, 8, 12, 24 and 48 h as whole seeds, cracked seeds, rapeseed meal, and as pelleted, barley-based diets containing 65 g rapeseed meal/kg. The seven transgene fragments ranged from 179 to 527 bp and spanned the entire 1363 bp EPSPS transgene. A 180 bp ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) small subunit fragment and a 466 bp 16S rDNA fragment were used as controls for endogenous rapeseed DNA and bacterial DNA respectively. The limit of detection of the PCR assay, established using negative controls spiked with known quantities of DNA, was 12·5 pg. Production of gas and NH3 was monitored throughout the incubation and confirmed active in vitro fermentation. Bacterial DNA was detected in all sample types at all time points. Persistence patterns of endogenous (Rubisco) and recombinant (EPSPS) rapeseed DNA were inversely related to substrate digestibility (amplifiable for 48, 8 and 4 h in whole or cracked seeds, meal and diets respectively), but did not differ between parental and GM rapeseed, nor among fragments. Detection of fragments was representative of persistence of the whole transgene. No EPSPS fragments were amplifiable in microbial DNA, suggesting that transformation had not occurred during the 48 h incubation. Uptake of transgenic DNA fragments by ruminal bacteria is probably precluded or time-limited by rapid degradation of plant DNA upon plant cell lysis.