The colonization of the plant root surface by the plant-growth promoting nitrogen-fixing bacterium Azospirillum brasilense is likely to be dependent on chemotaxis toward root exudates. However, the molecular mechanisms governing chemosensory behavior in most plant-associated bacteria are still poorly understood. This research project focuses on establishing the molecular basis of the chemosensory behavior in A. brasilense and its role in wheat root colonization. First, the function of the unique conserved domain of the central chemotaxis regulator CheA in sensing and behavior will be elucidated (research objective 1). Next, the function of novel chemoreceptors in behavior will be identified (research objective 2). Finally, the contribution of the general chemotaxis machinery and individual chemoreceptors in the establishment of the Azospirillum-wheat association will be determined (research objective 3). The outcome of the proposed research will enhance understanding of diversity in signal transduction in prokaryotes and directly benefit the field of biofertilizer design. The results obtained can be used for developing strains with improved abilities to colonize the rhizosphere of agronomically important plants, such as wheat. Sensing and behavior in bacteria are uniquely suited for broadening the educational experience of college students and enable the development of research-based educational materials for K-12 students. Undergraduate students (education objective 1) and K-12 science teachers (education objective 2) will be provided with research opportunities in the ongoing project. A module on "Microbial Sensing" will be implemented in the NSF-funded Bio-Bus project that provides inquiry-based learning opportunities and hands-on experiments to Georgia's K-12 students (education objective 3).
