Regionalisation of flora elements in field boundaries sensitive to hybridisation with genetically modified oilseed rape

Umweltwiss Schadst Forsch (2010) 22:252–263 DOI 10.1007/s12302-010-0134-5 IMPLICATIONS OF GMO-CULTIVATION AND MONITORING • SERIES Regionalisation of flora elements in field boundaries sensitive to hybridisation with genetically modified oilseed rape Angelika Wurbs · Michael Glemnitz · Frieder Graef · Bettina Funke · Sigrid Ehlert Received: 10 December 2009 / Accepted: 29 March 2010 / Published online: 11 May 2010 © Springer-Verlag 2010 Abstract Background, aim, and scope Gene flow via pollen dispersal to neighbouring non-genetically modified (GM) and organic fields or to biotopes containing the same crop species and/or their wild relatives are among the most debated potential environmental risks of GM crops. These crosses permit ingression of GM traits and may produce viable progeny. Current GM crop monitoring plans and concepts have not considered this a critical issue. In the present study, we develop a methodology for the regionalisation of the hybridisation risk of GM oilseed rape (OSR) (Brassica napus L.) with respect to related hybridisation partners (both OSR and related species) as well as neighbouring arable fields and biotopes. This methodology should constitute an important component of future spatial GM crop monitoring designs. Materials and methods A vegetation database containing occurrence frequencies of OSR crossing partners in Brandenburg state was analysed, and literature surveys were performed on OSR outcrossing proofs with regard to different wild species, the viability of progeny and the potential establishment of crosses. We aggregated detailed biotope maps for the entire Brandenburg state in order to differentiate the nine main biotope groups relevant as habitats for OSR and hybridising Brassicaceae. We determined the types and areas of biotopes neighbouring all arable fields Responsible editors: Gunther Schmidt · Winfried Schröder · Frieder Hofmann A. Wurbs · M. Glemnitz · F. Graef () · B. Funke · S. Ehlert Centre for Agricultural Landscape Research (ZALF), Eberswalder Str. 84, 15374 Müncheberg, Germany E-Mail: F. Graef Federal Agency for Nature Conservation (BfN), Konstantinstr. 110, 53179 Bonn, Germany 123 with an outside buffer of 50 m, and then ascertained whether the biotope composition outside the buffers was significantly different from that of the buffers. We then overlayed our buffering results with an ecoregion map of Brandenburg to upscale our results to larger regions. Results Brassica rapa presented the highest potential for hybridisation, reproduction and persistence in this environment, but Raphanus raphanistrum, Brassica oleracea, Hirschfeldia incana, Sinapis arvensis and Diplotaxis muralis are also significant potential crossing partners for OSR. The highest average frequency of species occurring in biotopes applies to arable lands, settlements and industrial areas, disturbed areas, road verges and gardens, which together cover 84.2 % of the total area and 74.6 % of the neighbouring biotopes. Related species occurring most often in Brandenburg are Descurainia sophia, feral OSR, Sinapis arvensis, Diplotaxis tenuifolia and Diplotaxis muralis. All biotopes relevant to OSR-related species are present in all Brandenburg ecoregions, but there are differences in the proportion of each biotope, especially hedgerows, arable land, gardens and road verges. The Uckermark and Oder valley can be considered slightly more critical. Discussion Hybridisation and persistence of GM OSR depends on (a) the related species’ potential to hybridise and produce viable progeny, (b) the frequency of hybridisation partners at different biotope types, and (c) the frequency of directly neighbouring arable fields with sensitive biotopes. Integration of these factors gives the following rank order of hybridisation risks for different biotopes in the agroenvironment: disturbed areas > arable land > road verges > settlements and industrial areas > gardens. Extrapolation of local relevée and biotope results to larger areas such as the Brandenburg state was shown to be feasible, and may also be done nationwide and EU-wide with suitable biotope datasets. Umweltwiss Schadst Forsch (2010) 22:252–263 Conclusions Cultivation of GM OSR in Brandenburg carries a considerable potential of hybridisation with related species and feral OSR in biotopes neighbouring arable fields. The methodology presented here is suitable to link spatially limited but highly detailed datasets on the occurrence of potential hybridisation partners for GM OSR with regional datasets and to extrapolate hybridisation risks, and therefore could serve as a monitoring instrument. Recommendations and perspectives We suggest that populations of related species and the potential spread of GM traits should be monitored using a targeted approach. While further standardisation will be required, this methodology should be included as a regular component of GM crop monitoring. Keywords Brassica napus L. · Environmental effects · Field boundaries · Genetically modified crop · GM oilseed rape (OSR) · Hybridisation · Oilseed rape · Spatial range · Wild relatives 1 Background, aim and scope The cultivation area of genetically modified (GM) crops has dramatically increased over the past two decades and in 2008 covered 125 million hectares (James 2008). Oilseed rape (OSR) (Brassica napus L.) and its canola cultivars cover 5 % of the global biotech area. The potential adverse agronomic and environmental effects linked to both the genetic modifications and changes in agricultural practices have been the subject of intense debate in recent years (Champion et al. 2003; European Commission 2003; Graef et al. 2007). Among the potential environmental risks debated, gene flow via pollen dispersal to neighbouring fields and biotopes that may contain the same crop species and/or their wild relatives rank very high (Devos et al. 2004, 2005). As progeny from these crosses may be viable, in this way the GM traits can ingress into non-GM, organic fields and the environment (Beckie et al. 2006; Legere 2005). Detrimental effects on agriculture and/or the environment can occur if the progeny with the GM trait develops a selective advantage, spreads through cultivated fields and the environment, or if other long-term and/or cumulative effects occur triggering yet unknown environmental hazards. The longest persistence of GM OSR offspring known to date was reported by Warwick et al. (2007), who monitored persisting transgenic Brassica rapa hybrids over a 6-year period, in the absence of herbicide selection pressure and in spite of reduced fitness associated with its hybridisation. The hybridisation risk for OSR is considerably higher than that of other crops for the following reasons: a) High cross-pollination rate by wind and insects, predominantly bees (Mesquida et al. 1988). The range of 253 honey-bees and other pollinators typically covers up to a few kilometres (Osborne et al. 2007; Steffan-Dewenter and Kuhn 2003). b) (...truncated)