Fates and Impacts of the Genetically Modified Plant Growth-Promoting Bacterium Pseudomonas Fluorescens SBW25, Under Controlled and Field Conditions

摘要

Plant growth-promoting bacteria may be used in agriculture to minimize the utilization of chemical pesticides and fertilizers. This thesis studies one plant growth-promoting bacterial strain. Pseudomonas fluorescens SBW25, and its interaction with winter wheat, potato and tomato in both field and laboratory conditions. This bacterium was tagged with a novel marker gene cassette containing gfp (green fluorescent protein), laxAB (bacterial bioluminescence) and telABkilA (potassium tellurite oxide resistance) and the resulting strain SBW25-tgl was released in the first field total with a genetically modified microorganism in Sweden. Bacterial numbers on wheat plants and in soil were dominated by selective plating on media containing potassium tellurite oxide, the impact of SBW25-tgl on wheat plant growth was measured using plant length and weight, and possible effects on resident bacterial and fungal microflora was evaluated throughout the 8 months sampling period using terminal restriction fragment length polymorphism (T-RFLP). The GMM was found in high numbers on all plant parts throughout the 8 months period, but only minor impacts were found on native microflora due to bacterial (GMM or wild-type) inoculation.