ENDOPHYTE BACTERIA AS AN OPPORTUNITY TO ENHANCE BIOLOGICAL NITROGEN FIXATION IN PLANTS

The goals of our project are to identify and manipulate fundamental features that are essential to establishing successful endophyte relationships that provide the plant with growth promoting levels of fixed nitrogen. We will identify the genes that govern endophyte/host relationships in Gluconacetobacter diazotrophicus, an endophyte of the plants Triticum aestivum and Arabidopsis thaliana, that is able to fix nitrogen from the atmosphere. This information will allow us to begin converting the ideal nitrogen-fixing production bacterium, Azotobacter vinelandii, into a functioning endophyte, which could then be applied to a large number of crop plants.We will also engineer Azotobacter vinelandii to direct the nitrogen fixed to nitrogen compounds that have lowered volatility and solubility, and that are also terminal products, so that they are not recycled by the bacteria or lost to the atmosphere or ground water, thereby reducing the negative environmental impact cause by application of fertilizer. Importantly, because these compounds do not inhibit nitrogen fixation, this manipulation should have the added benefit of increasing the amount of fixed nitrogen available to the plant. In parallel with these experiments, and informed by our success in engineering Azotobacter vinelandii strains that release nitrogen, we will engineer Gluconacetobacter diazotrophicus to release more fixed nitrogen to the plant. The final objective of this proposal contains a number of exploratory projects that will be performed by undergraduates as a portion of the training aspects of this proposal.