Selection of Nontarget Testing Organisms for ERA of GM Potato with Increased Resistance to Late Blight

The deliberate release of any genetically modified (GM) organism in the European Union requires an environmental risk assessment (ERA) prior to commercialisation, including impact assessment on nontarget organisms. We report from two expert workshops where a newly developed selection procedure for identification of ecologically relevant testing organisms was applied to the case of a GM potato with increased resistance to late blight, planned for cultivation in southern Scandinavia. Species known to contribute to important ecological functions in the receiving environment were selected in a stepwise procedure, to arrive at a practical number of ecologically relevant species that are likely to be exposed to the transgene and suitable for experimental testing. Four ecological functional categories were identified: herbivory and disease transmission, natural enemies, ecological soil processes and pollination. Among these, relevant nontarget species were identified for herbivores and soil living pathogens, natural enemies and decomposers/beneficial soil organisms. Out of a total of 16 herbivores, 17 soil-living pathogens, 49 natural enemies and 14 decomposers/beneficial soil organisms in the initial lists, 8 herbivores, 10 soil-living pathogens, 15 natural enemies and 11 decomposers/beneficial soil organisms were identified as possible testing organisms, based on ecological criteria. These findings are highly relevant for determining the scope and structure of an ERA of this type of GM potato. The selection procedure could not be completed because of insufficient information about tissue- and developmental stage-specific expression levels of the transgenic products for this particular GM potato. Thus, the case study illustrates some of the difficulties and knowledge gaps that limit the relevance and quality of ERA of GM plants.