Botany and Plant Pathology Seminar Series
Speaker: Dr. Caitlyn Allen - Professor and Department Chair - University of Wisconsin
Topic: Doing Well by Making Do: How Ralstonia solanacearum does practically everything with nitrate
When: Wednesday, April 10, 2013 at 3:30 pm in WSLR 116


Ralstonia solanacearum is a soilborne vascular pathogen that causes bacterial wilt disease of many important crops. Tomato xylem fluid contains mM amounts of nitrate, and the transcriptome of R. solanacearum revealed that the bacterium actively metabolizes inorganic nitrogen during tomato pathogenesis. We combined biochemical and genetic analyses to explore the roles of these core metabolic pathways in bacterial wilt virulence.  Our data suggest that R. solanacearum depends on both nitrate assimilation and denitrification to overcome plant defenses and cause disease.  In addition to its predictable nutritional role, the nitrate assimilatory pathway is also required for normal regulation of the nitrogen-rich extracellular polysaccharide (EPS), a major virulence factor. We found that R. solanacearum uses denitrification to generate energy in low-oxygen environments inside plants. Unexpectedly, the denitrifying pathway also appears to play a critical role in suppressing plant host defenses.

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