Towards biological nitrogen fixation in monocotyledonous plants - study plant genes for colonization and nitrogen fixation by Gluconacetobacter diazotrophicus

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Nitrogen is an essential nutrient for attaining high yields for various crops, especially cereal crops. Shortfalls in available nitrogen in soils are usually provided by use of industrial fertilizers. Nitrogen fertilizers are costly and are the highest cost to grow various crops, especially the cereal crops. In addition, nitrogen fertilizer uptake by crops is usually low, often lower than 50%. Unused fertilizers cause major environmental pollution problems. Gluconacetobacter diazotrophicus is a bacterium that freely lives in intercellular spaces of sugarcane plants. The bacterium can actively fix atmosphere nitrogen and provides significant amounts of nitrogen to sugarcane plants. G. diazotrophicus has a wide range of growth conditions, does not form specific structure with plants (like nodules in legume plants), and appears to be less species specific. Exploration of the nitrogen fixation feature of G. diazotrophicus in other cereal crops may lead to nitrogen fixation in these types of plants. This research will use genomics approaches to study plant gene involvement in G. diazotrophicus colonization and nitrogen fixation in cereal plants. A new grass genomics model plant, Brachypodium distachyon (Brachypodium) will be used in the research. Brachpodium has a small genome, small physical size and a short lifecycle. The draft genome sequence of Brachypodium has been recently revealed. A large number of insertion mutants has been developed. Brachypodium is an ideal plant for studying nitrogen fixation of G. diazotrophicus in cereal plants. Global gene expression of Branchypodium plant upon G. diazotrophicus colonization will be studied. A large number of Brachypodium insertion mutants relating to different aspects of nitrogen fixation will be investigated upon G. diazotrophicus infection. Data from microarray study and mutant study will be analyzed collectively. Plant genes responding to colonization and involving in nitrogen fixation by G. diazotrophicus will be analyzed. The information obtained from the research will be useful for use of G. diazotrophicus for nitrogen fixation in cereal crops.