Based on international findings, Irish co-existence guidelines for the cultivation of GM potato stipulate that an isolation distance of 20 m is required to minimize the spread of transgenic pollen in accordance with required labeling thresholds. As potato tolerant to Phytophthora infestans is the most applicable GM crop from an Irish context, we tested the efficacy of this isolation distance under Irish environmental conditions using the conventional variety Désirée as a pollen donor and the male-sterile variety British Queen as a pollen receptor. Gene flow was determined by scoring for berry presence on receptor plants and confirmed using a microsatellite marker system designed to assess paternity in F1 seedlings. 99.1% of seedlings recovered were identified as having Désirée paternity. Whereas 19.9% (140/708) of total berries formed on receptor plants occurred at a distance of 21 m from the pollen source, only 4 of these berries bore viable true potato seed (TPS), from which 23 TPS germinated. TPS-bearing berry formation was negatively correlated with distance from the pollen source, and although overall distribution of berries and seeds was non-random across the plot, no significant correlation was evident with respect to wind direction. Microsatellite markers were also used to confirm that the foraging beetle Meligethes aeneus is a vector for the transmission of potato pollen, but a more detailed statistical analysis of this dataset was limited by inclement weather during the trial. To conclude, we recommend that a two-tiered system be established in regard to establishing isolation distances for the experimental trial and commercial cultivation of GM potato in Ireland, and that responsible crop management be adopted to minimize the establishment of TPS-derived volunteers, which we have noted will emerge through a rotation as a result of pollen-mediated gene flow.

Many crop species are able to hybridize with related weedy or wild relatives, which could lead to transfer of cultivar genes, and among them transgenes, into wild populations. It is not clear, however, whether the hybrids and their descendants are able to survive and reproduce in natural habitats, as inherited cultivar traits may be maladaptive under such conditions. To test this, we produced hybrid (F1) seeds by controlled crosses between wild and cultivated carrots (Daucus carota ssp. carota and ssp. sativa, respectively) and sowed them into three Danish grasslands of different age, in parallel with seeds of wild carrots. Replicate plots were sown in fall and spring. Survival and flowering of the emerging plants were monitored for the following three years. Both hybrid and wild carrots survived and flowered in highest frequency at a recently disturbed site, and much less at two older sites. Hybrids emerged in higher proportions than wild carrots in the first year and survived to similar or slightly lower frequencies at the end of the experiment. Hybrids flowered as frequently or slightly less frequently than wild plants, and developed fewer and smaller umbels. Despite a somewhat lower reproductive potential compared to wild carrots, first generation hybrids between cultivated and wild carrots are likely to survive and produce offspring in natural grasslands in Denmark. This, together with other studies, suggests that cultivar genes may transfer relatively easily into wild carrot populations.

Development of transgenic triticale as a platform for novel bio-industrial products is predicated on an environmental biosafety assessment that quantifies the potential risks associated with its release. Pollen-mediated gene flow to related species and conventional triticale varieties is one pathway for transgene movement. A tier 1 quantification of triticale hybridization was conducted by emasculating and hand pollinating flowers under greenhouse conditions. Approximately 2000 manual pollinations were conducted for each cross and its reciprocal between two triticale genotypes: a modern triticale cultivar (AC Alta) and primary triticale (89TT108), and common wheat, durum wheat and rye. The frequency of outcrossing, hybrid seed appearance and weight, and F1 emergence and fertility were recorded. Outcrossing, F1 emergence and fertility rates were high from crosses between triticale genotypes. Outcrossing in inter-specific crosses was influenced by the species, and the genotype and gender of the triticale parent. In crosses to common and durum wheat where triticale was the male parent, outcrossing was ≥73.0% and ≥69.5%, respectively, but ≤23.9% and ≤3.0% when triticale was the female parent. Overall, outcrossing with rye was lower than with common and durum wheat. F1 hybrid emergence was greater when triticale was the female parent. With the exception of a single seed, all wheat-triticale F1 hybrid seeds were non-viable when triticale was the male parent in the cross. Only seven durum wheat-triticale F1 hybrids emerged from 163 seeds sown, and all were produced with triticale 89TT108 as female parent. With rye, 8 F1 hybrids emerged from 38 seeds sown, and all were produced from crosses to AC Alta; five with AC Alta as the female parent and three as the male. Interspecific F1 hybrids were self-sterile, with the exception of those produced in crosses between common wheat and triticale where triticale was the female parent. Tier 2 hybridization quantification will be conducted under field conditions.

Four GM plant species (Arabidopsis thaliana, Brassica napus, Nicotiana benthamiana and N. tabacum), each expressing the gene encoding the jellyfish green fluorescent protein (GFP) regulated by the cauliflower mosaic virus (CaMV) 35S RNA promoter, were assessed for the extent of transgene silencing and viral genome integration following infection by CaMV. The first three species are systemic hosts of CaMV, while N. tabacum is only a local host for a few strains of CaMV. A generalized systemic silencing of the GFP transgene was not observed in a total of 100 plants of each species infected with CaMV, although some localized loss of GFP was observed in CaMV-infected N. benthamiana leaves, and some loss of fluorescence was observed in older leaves of uninfected as well as infected plants. Progeny seedlings obtained from the above infected plants also did not exhibit transgene silencing showing that virus infection did not affect the stability of the transgene. These progeny plants also did not show signs of virus infection, indicating that the presence of the CaMV 35S RNA promoter sequences in the plant genome did not potentiate seed transmission of the virus. Integration of infective CaMV into the CaMV 35S RNA promoter could not be detected in 944 samples taken from leaves of the above infected plant species or in 2912 samples taken from progeny seedlings. Based on a detection limit of one copy per 4000 haploid genomes, we conclude that if integration of virus does occur into the CaMV 35S RNA promoter, then it occurs at such a low frequency as to be insignificant.

The European honey bee (Apis mellifera) is important both for pollination and for honey production. Pollen is the major protein source for bees, which exposes them directly to changes in pollen quality e.g. through genetic engineering. In order to create a worst case scenario regarding pea lectin (PSL) expressed transgenically in oilseed rape anthers and pollen, the maximum amount of dried pollen that could be mixed in an artificial diet without negatively affecting larval performance (1.5% w/w) was fed to bee larvae. Pollen from two transgenic plant lines expressing PSL up to 1.2% of total soluble protein and pollen from one non-transgenic line was added to the same diet and used as a pollen control. When these three pollen diets and the control diet (without added pollen) were compared, no negative effect from the pollen of the transgenic plants could be detected on larval mortality, weight, or development time. An increased weight and a reduced developmental time were recorded for larvae on all diets containing pollen when compared to the diet without pollen.