9728184 Kennedy Acetobacter diazotrophicus is a nitrogen-fixing bacterium isolated from sugarcane grown throughout the world. It inhabits the interior spaces of sugarcane but not its outside surfaces or nearby soils. Evidence that this bacterium supplies fixed nitrogen for plant growth was obtained in the PI's laboratory: sugarcane plants inoculated with A. diazotrophicus grew better than did uninoculated plants or plants inoculated with mutants unable to fix nitrogen. This symbiosis provides a model system for studying the potential benefit of bacterial nitrogen fixation in grasses and cereals. The objectives are 1) to determine how much fixed N is supplied to the plants: 2) to learn whether production of growth hormones by A. diazotrophicus also benefits plant growth; and 3) to characterize how A. diazotrophicus colonizes sugarcane using bacteria tagged with fluorescent markers. The results will provide insight into how other monocots, such as corn, wheat or rice might benefit from nitrogen-fixing bacteria.
