We have overcome some of these problems by constructing and deploying bacterial reporters which fluoresce when particular nutrients are present in the root/soil environment. The reporters are simply inoculated into environmental chambers containing plants, and the root systems in the chambers are later observed by microscopy. The locations of fluorescing bacteria indicate regions where particular nutrients are detected by the biosensing bacteria. Using this technology, nutrients and their locations in time and space can be observed around plant roots, and in soil. We are applying the technology to study how sugars, organic acids, and bulk carbon support growth of bacteria around the roots of a variety plant species. Ultimately we hope to use these biosensors to investigate how carbon flow into the rhizosphere is modified in response to changes in plant physiology. For example, are there changes in carbon levels or spatial distributions of carbon near the root during the day/night cycle, do carbon levels or locations change when plants are limited for particular nutrients? In addition, we are currently using this technology to see if there is a correlation between release of certain compounds from plants, and the ability of these plants to clear pollutants from contaminated soil.

This work is multidisciplinary and is being done in collaboration with the departments of Ecology and Evolutionary Biology (Dr. Zoe Cardon)