The potential commercialization of genetically modified herbicide-tolerant (GMHT) oilseed rape in Europe raises various concerns about their potential environmental and agronomic impacts, especially those associated with the escape of transgenes. Pollen of oilseed rape can be dispersed in space, resulting in the fertilization of sympatric compatible wild relatives (e.g. Brassica rapa) and oilseed rape cultivars grown nearby (GM and/or non-GM Brassica napus). The spatial and temporal dispersal of seeds of oilseed rape may lead to feral oilseed rape populations outside the cropped areas and oilseed rape volunteers in subsequent crops in the rotation. The incorporation of a HT trait(s) may increase the fitness of the recipient plants, making them more abundant and persistent, and may result in weeds that are difficult to control by the herbicide(s) to which they are tolerant. Vertical gene flow from transgenic oilseed rape to non-GM counterparts may also have an impact on farming and supply chain management, depending on labelling thresholds for the adventitious presence of GM material in non-GM products. Given the extent of pollen and seed dispersal in oilseed rape, it is obvious that the safe and sound integration of GMHT oilseed rape in Europe may require significant on-farm and off-farm management efforts. Crucial practical measures that can reduce vertical gene flow include (1) isolating seed production of Brassica napus, (2) the use of certified seed, (3) isolating fields of GM oilseed rape, (4) harvesting at the correct crop development stage with properly adjusted combine settings, (5) ensuring maximum germination of shed seeds after harvest, (6) controlling volunteers in subsequent crops, and (7) keeping on-farm records. The implementation of the recommended practices may, however, be difficult, entailing various challenges.

The development of transgenic crops as production platforms for biogenic agents will largely depend on the success of efforts to confine the genes and their expressed proteins in field environments. We have used quantitative exposure assessment to evaluate how management practices affect materials escape due to outcrossing by pollen flow or grain loss during harvest operations. Specifically, we study the use of maize to produce biogenic agents within field-confined systems. Decision trees representing simplified schemes of fully conforming (designed to comply with current regulatory standards for field confined trials), partially conforming, and non-conforming management practices were developed. Exemplifying assumptions and published data for conformance and material fate probabilities were used in Monte Carlo simulations to forecast materials escape by pollen outcrossing and harvest operations from a 1 ha source field. Deterministic analyses showed fully conforming confinement management restricted materials loss to low levels (for this example, outcrossing produced <1 in 106 kernels in receptor fields). The corresponding high-end (90th percentile) probabilistic result was 16- and 4333-fold higher (relative to deterministic outcrossing = 1) for outcrossing and harvest loss, respectively. For partially conforming practice, high-end outcrossing ranged from 100- to >15 000-fold over the base result in receptor fields, and harvest loss was >10 000-fold over the base result. For non-conforming practice, high-end outcrossing produced >15 000-fold greater kernels in receptor fields and high-end harvest loss was at least 19 000-fold greater. Deterministic estimates of off-field loss by machine transfer are as much as 30 000-fold higher for non-conforming operations relative to the base case of pollen outcrossing. Better knowledge of failure frequencies for confinement management practices, improved physical models of materials flows, refined analysis of confinement loss probabilities using quantitative tools, and decision analysis to improve and audit management system performance are all needed to extend understanding of confinement integrity beyond the exemplifying case used here.

The safety and impact on the environment of transgenic crops are important issues, and studies have shown that pollen from transgenic Bt (Bacillus thuringiensis) corn (Zea mays L.) may kill nontarget insects. To develop an algorithm for assessing the environmental effect of transgenic crops, we arranged a field experiment in Tsukuba, Japan. Pollen dispersal and deposition were measured inside and outside a cornfield throughout the flowering period. Weather conditions such as wind speed and direction were measured at the same time. Pollen dispersal peaked 1 week after the start of flowering and continued for 12 days thereafter. The variation in daily pollen dispersal was similar at all observation points. Both pollen dispersal and deposition decreased exponentially with distance from the cornfield on all days. We estimated potential pollen deposition with a quasi-mechanistic model that incorporates the effects of wind direction, wind speed, and flowering intensity. The daily potential deposition was summed over the flowering period, and then the relationship between distance from the cornfield and the integrated potential deposition was estimated. It was possible to show the effective area of the environmental risk zone posed by genetically modified pollen by combining the distance/deposition relationship with the dose/response relationship derived from a laboratory assay. The algorithm described here can be applied to various wind-pollinated plants to estimate both potential and integrated pollen deposition.

Maize diversity is widespread in Mexico and it has been stewarded by campesinos in small communities until the present. With the arrival of transgenic maize, the objective of this study is to analyze possible scenarios that could result if genetically modified maize were not regulated and openly available in Mexico. By applying a simple logistic model based on the conditions of maize production in Mexico, the dispersion of transgenic maize in different situations within fields of farmers is described. In traditional open systems of freely exchanged seed within communities it is concluded that the most likely outcome of GM maize release is the incorporation of transgenes in the genome of Mexican germplasm and possibly in that of teosinte.

Determining the frequency of crop-wild transgene flow under field conditions is a necessity for the development of regulatory strategies to manage transgenic hybrids. Gene flow of green fluorescent protein (GFP) and Bacillus thuringiensis (Bt) transgenes was quantified in three field experiments using eleven independent transformed Brassica napus L. lines and the wild relatives, B. rapa L. and Raphanus raphanistrum L. Under a high cropto wild relative ratio (600:1), hybridization frequency with B. rapa differed among the individual transformed B. napus lines (ranging from ca. 4% to 22%), however, this difference could be caused by the insertion events or other factors, e.g., differences in the hybridization frequencies among the B. rapa plants. The average hybridization frequency over all transformed lines was close to 10%. No hybridization with R. raphanistrum was detected. Under a lower crop to wild relative ratio (180:1), hybridization frequency with B. rapa was consistent among the transformed B. napus lines at ca. 2%. Interspecific hybridization was higher when B. rapa occurred within the B. napus plot (ca. 37.2%) compared with plot margins (ca. 5.2%). No significant differences were detected among marginal plants grown at 1, 2, and 3 m from the field plot. Transgene backcrossing frequency between B. rapa and transgenic hybrids was determined in two field experiments in which the wild relative to transgenic hybrid ratio was 5–15 plants of B. rapa to 1 transgenic hybrid. As expected, ca. 50% of the seeds produced were transgenic backcrosses when the transgenic hybrid plants served as the maternal parent. When B. rapa plants served as the maternal parent, transgene backcrossing frequencies were 0.088% and 0.060%. Results show that transgene flow from many independent transformed lines of B. napus to B. rapa can occur under a range of field conditions, and that transgenic hybrids have a high potential to produce transgenic seeds in backcrosses.

We monitored pollen-mediated transgene dissemination from commercial transgenic squash CZW-3 into its wild relative Cucurbita pepo ssp. ovifera var. texana (C. texana). Transgenic squash CZW-3 expresses the neomycin phosphotransferase II (nptII) gene and the coat protein (CP) genes of Cucumber mosaic virus (CMV), Zucchini yellow mosaic virus (ZYMV), and Watermelon mosaic virus (WMV); thereby, it is resistant to these three aphid-borne viruses. The rate of NPT II and CP transgene introgression increased with overlapping flowering patterns and a high ratio of transgenic F1 hybrids (C. texana × CZW-3) to C. texana. Transgene transfer also readily occurred from transgenic F1 hybrids into C. texana over three generations in field settings where test plants grew sympatrically and viruses were not severely limiting the growth, and fruit and seed production of C. texana. In contrast, introgression of the transgenes into C. texana was not sustained under conditions of high viral disease pressure. As expected, C. texana progeny that acquired the CP transgenes exhibited resistance to CMV, ZYMV, and WMV. This is the first report on transgene dissemination from a transgenic crop that exhibits disease resistance and hybridizes with a wild plant species without loss of fertility.

Genetically-engineered (GE) crops such as those expressing insecticidal Bacillus thuringiensis (Bt) toxin genes have the potential to greatly reduce the use of broad spectrum insecticides and increase crop productivity. However, development of resistance by the target insect species is an important consideration in the deployment of this strategy. In areas where GE crops are deployed on a large scale, current resistance management strategies rely on a ‘refuge strategy’, comprising the incorporation of a certain proportion of non-GE plants in the agro-ecosystems, to conserve susceptible individuals of the target pests. In the USA, simulation models indicate that at least 20% of the crop should be non-Bt plants. In Africa, the target lepidopteran stemborers attack a wide range of wild grass species as well as cultivated cereal crops. Wild grasses generally occur in the vicinity of maize and other cereal fields, and may provide a refuge if GE crops are in the farming systems. To assess the quality of these grasses as refuges, it is critical to obtain information about their size and spatial distribution. In this study, we have assessed the abundance and diversity of alternative refuge of stemborers, mainly wild grasses occurring in the proximity of maize fields, in Trans-Nzoia district, one of the most important maize growing areas in Kenya. The proportion of wild host plants relative to maize was found to decline from 100% during the non-cropping season to <8% during the maize-growing season. The Shannon-Weaver diversity index indicated high variation in the diversity of wild hosts of stemborers between agro-ecological zones in the district. The results of this study are discussed in light of the possible role that wild host plant species might play in stemborer resistance management following the introduction of Bt maize.

Pseudomonas fluorescens is a normal inhabitant of the soil rhizosphere. The use of genetically altered strains of P. fluorescens in bioremediation has led to the need for effective monitoring of such cells released into the environment. In this study, we present data on the persistence in soil of P. fluorescens harboring gfp (green fluorescent protein) or lux (bioluminescence) genes. Comparisons were made between strains marked chromosomally and strains carrying these markers on a plasmid. Overall effects of plasmid carriage on culturability were also examined. Sterile soil microcosms were inoculated with washed cells to a final concentration of ca. 106 CFU.g–1 and placed at 5, 23, and 35–37 °C. Samples were taken periodically and examined for culturability and viability, using the substrate responsiveness assay. Our results indicated no significant loss of culturability at 5 and 23 °C for a period of over one year. In contrast, cells of P. fluorescens incubated at 35–37 °C entered the viable but nonculturable state within 7 days. All cells labeled with gfp retained fluorescence regardless of culturability, suggesting that the green fluorescent protein can be of value in monitoring the presence of cells following their release to the environment. Because fluorescence was maintained regardless of the cells’ physiological state, this protein may also be an indicator of cell viability.

We compared some fitness components of the wild squash species Cucurbita pepo spp. ovifera var. texana (C. texana) and three generations of hybrids (F1, BC1, and BC2) between C. texana and commercial transgenic squash CZW-3 over three consecutive years under field conditions of low (LDP) and high disease pressure (HDP) by Cucumber mosaic virus (CMV), Zucchini yellow mosaicvirus (ZYMV) and Watermelon mosaic virus (WMV). Transgenic squash CZW-3 expresses the coat protein (CP) genes of CMV, ZYMV, and WMV, and is resistant to these three aphid-borne viruses. Across all HDP trials, transgenic BC1 and BC2 hybrids expressing the three CP genes grew more vigorously, displayed resistance to CMV, ZYMV, and WMV, and produced a greater number of mature fruits and viable seeds than nontransgenic hybrid segregants and C. texana. Transgenic F1 hybrids behaved similarly to BC1 and BC2 hybrids but grew less vigorously than C. texana. In contrast, across all LDP trials, C. texana outperformed the transgenic and nontransgenic hybrid segregants. Further, only one back cross was necessary to recover individuals with most of the C. texana characteristics and yet maintain virus resistance. Our data suggest that C. texana acquiring CP transgenes upon hybridization and introgression could have a selective advantage if CMV, ZYMV, and WMV are severely limiting the growth and reproductibility of wild squash populations.

Hybridization of Brassica napus L. (oilseed rape) and Raphanus raphanistrum L. (wild radish) has been demonstrated, and may be the first step towards introgression of transgenes in this wild relative. If wild radish were to display a new adaptive advantage by expressing the transgene, this could modify the ecological balance of species within the agro-ecosystem. To determine if transgenes remained stable in the hybrid, the frequency of herbicide resistance was studied over four advanced generations of hybrid progeny (G8 to G11) that were subjected to herbicide selection pressure. It is expected that hemizygous resistant plants containing an herbicide resistance transgene back-crossed to wild radish would have 50% resistant progeny. In each of the G8 to G11 generations, only 18% of the progeny from resistant plants were resistant. The chromosome complement of herbicide-susceptible progenies, analyzed at G9, was not different from that of wild populations of wild radish. Herbicide-resistant G9 progeny showed higher chromosome instability, and one third of the progeny contained a supernumerary chromosome. These results suggest that in the presence of herbicide selection pressure, the transgene for herbicide resistance would be maintained despite a lack of stabilized introgression. In the absence of selection, the frequency of resistance in the population is expected to decline.

Transgenic plants result from the isolation and insertion of genes into plants by means other than conventional breeding techniques, making it possible to isolate a gene that controls a valuable trait without also inserting thousands of other genes, as can occur with other methods. Transgenic plants potentially can provide substantial benefits to humans, but they can also pose risks to ecosystems, nontarget species and even to humans. I utilize the U.S. regulatory experience with chemical substances to provide some background for locating the strengths and weaknesses of different legal structures as well as providing an opportunity to learn from them. Learning from that case study and different legal structures utilized therein, as well as from the state of the world in which transgenic plants will be introduced and the state of the relevant sciences combined with a National Research Council Report on transgenic plants, this essay assesses the regulatory procedures that the U.S. Department of Agriculture uses to evaluate the risks from transgenic plants. These legal structures, although well suited for identifying risks before there is extensive exposure, have a number of shortcomings for reviewing the products of a new and not well-understood technology. The U.S. could take some steps toward improving its reasonable, tiered, pre-market approach for reviewing the risks from transgenic plants by following the NRC recommendations and learning from shortcomings of the regulation of chemical risks. Whether it will be or not remains to be seen.

The effect of food components on degradation of DNA by DNase I (EC 3.1.21.1) was monitored by electrotransformation of Escherichia coli, making it possible to determine the number of plasmid molecules capable of giving rise to transformed cells. The transformation frequency increased linearly with the plasmid number within the range of 2 × 106 to 2 × 1010. DNA degradation was reduced by one order of magnitude in the presence of 0.05% (w.v–1) maltol or 1 mM putrescine. Complete inhibition of degradation was observed with ≥0.2% (w.v–1) maltol, ≥0.01% (w.v–1) octyl gallate or ≥0.5 mM of spermine. To monitor degradation of plant DNA during food processing, a real-time PCR system was established. The ratio of copy numbers of a potato gbss DNA fragment of 325 bp and a nested 96 bp fragment was determined. The latter served as internal reference for normalization. The system made it possible to exclude process-dependent changes of DNA concentration in the food matrix. Processing of genetically modified potatoes to dried potato sticks, crisps or flakes was studied and drying steps were shown to exert the strongest effect on DNA degradation, resulting in a drop of the ratio from 0.73 to 0.16.

Gene constructs containing the Cauliflower mosaic virus (CaMV) 35S promoter and a sequence coding either for a green fluorescent protein (GFP) or for firefly luciferase were transfected into Chinese hamster ovary (CHO) cells. Both reporter genes were expressed to significant levels. The 35S promoter was 40 times less active than the human eF1α promoter, which is known to be one of the most potent promoters in mammalian cells. The 35S promoter must therefore be considered to be a promoter of significant potency in mammalian cells. RT-PCR analysis suggested that transcription initiation in CHO cells occurred between the TATA box and the transcription start site of the 35S promoter that function in plant cells. Further analysis by 5’RACE confirmed that transcription was initiated in CHO cells at different sites located essentially between the TATA box and the plant transcription start site, showing that 35S promoter activity in animal cells is due to the presence of promoter elements that are functional in mammalian cells, but that are not those used in plants. The data reported here raise the possibility that genes controlled by the 35S promoter, which is commonly used in transgenic plants, have the potential for expression in animal cells.

Impact assessment studies rely on relevant sampling methods. Correct evaluation of methods can be done by their concurrent use in the same sampling site and period. Collecting webs of Theridion impressum L. Koch (Araneae: Theridiidae) may serve as an arthropod sampling method: empty cuticles of prey items remain attached to the back side of the leaves with adhesive silk. Our study aimed to compare the applicability of the two methods concurrently (spider web survey and whole plant visual sampling) in a risk assessment study. The spider web survey recorded more predatory insect families than the whole plant visual sampling. Both methods were able to detect significant differences in the quantity of predatory insects in Bt vs. isogenic plots, but not in the same taxa (Nabidae: spider-web, 2001, Bt > Iso; Coccinellidae: plant sampling, 2001, Iso > Bt; Welsh-test, P < 0.05); thus, they could not confirm each other. The lack of confirmation can be explained by differences in the sensitivity and selectivity of the two methods. A web survey of T. impressum has the practical advantage that although we concentrate only on the one species during field sampling, we gain additional information on a wide range of foliage-dwelling arthropods. Due to several biological uncertainties, interpretation and explanation of the results remain problematic. Thus, additional research – based on in-situ observation and recording of T. impressum-prey interactions – is necessary before we could propose web survey method as a complementary tool in ecological impact assessment.

Transgenes from transgenic oilseed rape, Brassica napus (AACC genome), can introgress into populations of wild B. rapa (AA genome), but little is known about the long-term persistence of transgenes from different transformation events. For example, transgenes that are located on the crop’s C chromosomes may be lost during the process of introgression. We investigated the genetic behavior of transgenes in backcross generations of wild B. rapa after nine GFP (green fluorescent protein)-Bt (Bacillus thuringiensis) B. napus lines, named GT lines, were hybridized with three wild B. rapa accessions, respectively. Each backcross generation involved crosses between hemizygous GT plants and non-GT B. rapa pollen recipients. In some cases, sample sizes were too small to allow the detection of major deviations from Mendelian segregation ratios, but the segregation of GT:non-GT was consistent with an expected ratio of 1:1 in all crosses in the BC1 generation. Starting with the BC2 generation, significantly different genetic behavior of the transgenes was observed among the nine GT B. napus lines. In some lines, the segregation of GT:non-GT showed a ratio of 1:1 in the BC2, BC3, and BC4 generations. However, in other GT B. napus lines the segregation ratio of GT:non-GT significantly deviated from 1:1 in the BC2 and BC3 generations, which had fewer transgenic progeny than expected, but not in the BC4 generation. Most importantly, in two GT B. napus lines the segregation of GT:non-GT did not fit into a ratio of 1:1 in the BC2, BC3 or BC4 generations due to a deficiency of transgenic progeny. For these lines, a strong reduction of transgene introgression was observed in all three B. rapa accessions. These findings imply that the genomic location of transgenes in B. napus may affect the long-term persistence of transgenes in B. rapa after hybridization has occurred.

This article analyzes the development of notifications of genetically modified plants field trials in the European Union from 1991 to 2001, based on the data collected at the European level in the Summary Notification Information Format database. During this time period, a total of 1687 field trial notifications were received. The number of field trial notifications dropped by 76% between 1998 and 2001, mainly due to the de facto moratorium in place since 1999. Input traits (77%) dominated the field trial notifications during the last decade, while output traits were relevant in only 18% of all notifications, with a decreasing relevance during the last six years. In particular, field trial notifications on molecular farming were almost absent in the EU. Large companies focused their field trials on crops with a high grown area in the European Union and resistance traits, while public institutions showed interest in a large diversity of plants and traits. Finally, some conclusions on future impacts of the results of the study are drawn in this article.

This paper is the third in a series designed to demonstrate the application of rigorous, systematic hazard identification techniques to ecological systems. Here we use Hierarchical Holographic Modelling to identify the potential ecological hazards associated with the commercial release of herbicide tolerant oilseed rape. Hierarchical Holographic Models decompose complex systems into a series of sub-systems and consider interactions between the components and processes of these sub-systems in order to identify hazards. In this example we considered 1356 potential interactions between the biological, chemical and physical components and processes of the herbicide tolerant oilseed rape environment, and identified 152 potential hazards, grouped into 14 categories. The hazards were subsequently scored for degree of concern and plausibility, and then compared with an equivalent list of hazards generated independently by a checklist approach. The incidence of herbicide tolerant volunteers (and weeds) both on and off the farm had the highest average score of all the ecological hazard categories. The checklist based approach identified or implied 44% of the hazards identified in the Hierarchical Holographic Model, including nine of the ten hazards ranked most important. The checklist approach focussed almost exclusively on the phenotypic and genotypic hazards associated with herbicide tolerant oilseed rape and largely ignored the hazards associated with the circumstances surrounding its use. As a result the checklist identified only 6 out of the 79 potential hazards associated with changes to farming practice. The commercial release of herbicide tolerant oilseed rape will be associated with changes in tillage and the application of post-emergent herbicides. It may also lead to changes in spray schedules of insecticide and fungicide. Many of the environmental hazards identified with these changes are plausible and may warrant further investigation or targeted monitoring.

The monitoring of genetically modified organisms (GMOs) after deliberate release is important in order to assess and evaluate possible environmental effects. Concerns have been raised that the transgenic crop, Bt maize, may affect butterflies occurring in field margins. Therefore, a monitoring of butterflies was suggested accompanying the commercial cultivation of Bt maize. In this study, baseline data on the butterfly species and their abundance in maize field margins is presented together with implications for butterfly monitoring. The study was conducted in Bavaria, South Germany, between 2000–2002. A total of 33 butterfly species was recorded in field margins.A small number of species dominated the community, and butterflies observed were mostly common species. Observation duration was the most important factor influencing the monitoring results. Field margin size affected the butterfly abundance, and habitat diversity had a tendency to influence species richness. Sample size and statistical power analyses indicated that a sample size in the range of 75 to 150 field margins for treatment (transgenic maize) and control (conventional maize) would detect (power of 80%) effects larger than 15% in species richness and the butterfly abundance pooled across species. However, a much higher number of field margins must be sampled in order to achieve a higher statistical power, to detect smaller effects, and to monitor single butterfly species.