Abstract
(Sub-project to 838.06.060) The closest interactions between a genetically modified (GM) crop and its environment takes place in the rhizosphere and during the decomposition of crop residues. Affecting the natural interactions, and their still unknown consequences for soil fertility, have been hypothesized as potentially relevant hazard scenario of GM-crops requiring further investigation. In the rhizosphere, numerous bacteria, fungi and nematodes feed on GM plant roots and root exudates. During decomposition predominantly bacteria and fungi feed on GM plant material. Nematodes constitute a diverse group within the soil fauna, feeding on bacteria, fungi, other nematodes and plant-roots. This intimate feeding relationship with all major players in direct contact with plant residues implies that GM-crop effects in the rhizosphere and on the decomposer community will be reflected in the nematode community. Nematode abundance is high in virtually every soil, and the role of nematodes in processes underlying soil fertility is well characterized. Unlike many soil organisms, nematodes can be easily extracted from soil and their ecological relevance can be assessed accurately. This makes them, both from a biological and practical view, an ideal monitoring device for non-target effects of GM crops. As yet, most studies have focused on aboveground invertebrates, neglecting soil organisms. However, recent advances in nematology, like the use of small subunit ribosomal DNA to detect families, genera and often even species (23, 24), enable the use of nematodes with a much higher resolution than before. DNA barcodes are now being developed for individual nematode families, and quantitative PCR can be used to monitor changes in the nematode community at a large scale with unprecedented resolution.
Netherlands