Exploitable results Gene flow and interactions between introduced transgenic rhizobia, indigenous rhizobia, and other bacteria in the field: informing the debate on biosafety Although bacteria are important in many biotechnological industries including food, pharmaceuticals and agriculture, and are among the best-known organisms in terms of their genomes and laboratory genetics, paradoxically their population genetics and interactions outside the laboratory, especially in soil, are poorly understood. The biotechnological significance of this is clear: it is relatively easy to make novel genetic constructs, but difficult to predict the consequences of releasing them in the field. Bacterial population genetics urgently requires further development, both more empirical knowledge (from new molecular tools and better strategies for sampling populations) and a firmer theoretical framework (especially a clearer understanding of the relative importance of different gene transfer processes. This project will provide baseline knowledge of the genetic structure of indigenous populations of rhizobia in field soils, and assess the impact of GM releases of rhizobia (and, by analogy, other bacteria used as agricultural soil inoculants) against this baseline. Gene flow within rhizobial populations, between rhizobia and other bacterial groups, and between GM release strains and the indigenous community will be analysed, and the maintenance of genes and the fluctuations in the genetic composition of populations that arise through normal agricultural practice will be examined. Rhizobia, the nitrogen-fixing symbionts of legumes, are priority organisms for such studies and an excellent model because they are of biotechnological importance and essential for developing sustainable agricultural systems. They survive in soil and colonise the rhizosphere in addition to their important role in biological nitrogen fixation. The use of commercial rhizobial inoculants is an established agricultural practice, with a long history of agronomic, genetic and ecological studies and there is potential for commercial use of modified strains in the future. Acquisition of genes from indigenous bacteria Quantitative data and information are being compiled on the acquisition of genetic material by bacterial inoculants in the field and on the types of material involved in transfer, using rhizobia, currently the most important plant inoculants in Europe and worldwide. Data is being obtained from field sites where marked strains of Rhizobium and Bradyrhizobium released as inoculants in the past have become established. Recovered strains are being screened for evidence of acquisition of new genetic elements (bacterial plasmids, prophages, and transposable elements) during their time in the field. These are widespread in natural bacterial populations, can serve as markers of gene transfer, and may themselves confer significant new properties. Plasmid replication origins and insertion elements not present in the inoculant strains but which exist in indigenous populations has been identified. Rhizobium has been constructed with a glucuronidase (GUS) marker gene designed to facilitate screening for acquisition of plasmids from indigenous rhizobia, to be released in the field. Novel polymerase chain reaction (PCR) based methods for screening the genetic diversity of populations have been developed and detection limits of 1 genetically marked cell amongst 1E4 unmarked cells have been established. Searching for OpenAIRE data... There was an error trying to search data from OpenAIRE No results available
