Ellucidation of genes required for endophytic N-fixation and their role in plant growth promotion
P. JOUBERT (1), S. Doty (1) (1) University of Washington, U.S.A.

Nitrogen is one of the most important nutrients for plant growth, and fertilizers are heavily used worldwide to provide this nutrient. However, fertilizers are costly to produce and have significant negative impacts on the environment. Microorganisms within plants, termed endophytes, were isolated from wild poplar and willow plants and shown to promote growth in several other plant species as broadly diverse as rice, tomato, and Douglas fir. N-fixation was demonstrated in wild poplar and in hybrid poplar inoculated with a consortium of the endophytes from wild poplar. In order to better understand the genes involved in N-fixation by these endophytes, mutant libraries will be created by random transposon mutagenesis. The libraries will be screened for inability to grow on N-free medium. The Tn insertion sites will be identified by sequencing.  These results as well as a comparative genomics analysis with nodule-inhabiting rhizobia may provide insight into how endophytes protect nitrogenase from inhibitory oxygen.  The project will also provide mutants to be tested on plants for determining the relative importance of N-fixation in the observed growth promoting effects of endophytes. A better understanding of the processes involved in N-fixation could lead to the creation of an optimized consortia of naturally occurring, N-fixing endophytes that could reduce the need for fertilizers in the future.

Abstract Number: P2-31
Session Type: Poster