These Proceedings evolved from the OECD Co-operative Research Programme workshop on "Potential ecological impact of transgenic plants expressing viral sequencies", held at the Agricultural Biotechnology Center in Gödöllö, Hungary on 24-26 April 1997. The OECD Co-operative Research Programme At the Directorate for Agrieulture of the Organisation for Economie Co-operation and Development (OECD) a co-operative research programme for "Biological Resource Management" has existed since 1990. It foeuses on work in four specific topie areas, one of whieh is "Ecology and utilisation of new organisms" (Theme 3). The activities promoted by this programme are post-doctoral fellowships (announced annually), and the organisation of expert workshops (1-2 workshops per Theme per year). The 26 OECD member countries participating in this programme are: Australia, Austria, Belgium, Canada, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, ltaly, Korea, Japan, the NetherIands, New Zealand, Norway, Poland, Portugal, Spain, Sweden, SwitzerIand, Turkey, the UK, and the USA.

1 Virus Evolution; the Past, a Window on the Future?

2 Systematic Search for Recombination Events in Plant Viruses and Viroids
3 Different Mechanisms of Homologous and Nonhomologous Recombination in Brome Mosaic Virus, a Model Plant RNA Virus
4 Studies on RNA Recombination in vivo and in vitro
5 Significance of RNA Recombination in Capsid Protein-Mediated Virus-Resistant Transgenic Plants
6 Transgenic Plants Expressing Viral Sequences Create a Favourable Environment for Recombination Between Viral Sequences
7 Behavior of Cucumovirus Pseudorecombinant and Recombinant Strains in Solanaceous Hosts
8 Recombination Between Cauliflower Mosaic Virus and Transgenic Plants that Contain CaMV Transgenes: Influence of Selection Pressure on Isolation of Recombinants
9 Synergy of Virus Accumulation and Pathology in Transgenic Plants Expressing Viral Sequences
10 Risk Assessment of Transgenic Plants Expressing the Coat Protein Gene of Plum Pox Potyvirus
11 Mixed Infections and Genetic Exchange Occur in Natural Populations of Cucumber Mosaic Cucumovirus
12 The Potential of a Beneficial Satellite RNA of Cucumber Mosaic Virus to Acquire Deleterious Functions: Nature Versus Greenhouses
13 Ecological Impact of Transgenic Virus-Resistance in Crop, Weed, and Wild Plant Populations (Due to Potential Alterations of Plant Invasiveness)
14 Risk Assessment of Gene Flow Associated with the Release of Virus-Resistant Transgenic Crop Plants
15 Concluding Remarks and Recommendations
Index of Viruses
Index of Plants.