Employing a composite gene-flow index to numerically quantify a crop’s potential for gene flow: an Irish perspective

Abstract

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-tovolunteer 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.

Facilitating co-existence by tracking gene dispersal in conventional potato systems with microsatellite markers

“…Eight of these submissions relate to the experimental release of transgenic potato with improved resistance to potato blight (P. infestans), which is a much desired agronomic trait of significant economic potential in Ireland (Flannery et al, 2005). As the potential economic benefit of cultivating a blight-resistant potato line becomes more apparent to potato growers, it is reasonable to assume that it will be the larger producers who will initially decide to adopt the technology (Fernandez-Cornejo et al, 2001) due to the reduced cost base, but also because of the increased convenience factor associated with GM crop cultivation, which could appeal greatly to Ireland's part-time farmers (∼48%, http://www.teagasc.ie/).…”

“…Establishing effective cropping regimes for co-existence that minimize both the potential and subsequent outcome of a gene flow event is a critical step to preserving the genetic integrity of existing crop systems and affording tillage farmers the opportunity to choose the tillage system (organic, conventional, GM) they wish to employ. A crop's potential for gene flow can be quantified by assessing the four primary modes of gene dispersal: * Corresponding author: ewen.mullins@teagasc.ie pollen-mediated crop-to-wild relative, pollen-mediated crop-to-crop, seed-mediated crop-to-volunteer and seedmediated crop-to-feral (Flannery et al, 2005). The imposition of separation distances between GM and related non-GM crops is an accepted measure to offset the challenge pollen-mediated gene flow poses to co-existence (ACRE, 2004;Eastham and Sweet, 2002;McGill et al, 2005;Tolstrup et al, 2003).…”

“…The imposition of separation distances between GM and related non-GM crops is an accepted measure to offset the challenge pollen-mediated gene flow poses to co-existence (ACRE, 2004;Eastham and Sweet, 2002;McGill et al, 2005;Tolstrup et al, 2003). In contrast, seed-mediated gene flow presents an equal if not greater challenge to the effective management of GM crops (Flannery et al, 2005;McHughen, 2006), but measures to minimize the potential for seed-mediated gene flow are less specific, due to the current deficit in research-based support for regulators (McHughen, 2006).…”

“…We have previously published a gene flow index (GFI) model that describes the quantification of a crop's potential for both pollen and seed-mediated gene flow (Flannery et al, 2005). From this model, the composite gene flow potential of potato was calculated to be 11/27.…”

“…During the compilation of the GFI model (Flannery et al, 2005) we were conscious of our reliance on international reports, due to a scarcity of Irish-specific research. Though this was especially the case for potato, we concluded that the datasets described in the peer-reviewed reports (Conner and Dale, 1996;McPartlan and Dale, 1994;Tynan et al, 1990) were applicable to Irish agronomic systems.…”